NAT44: add support for session timeout (VPP-1272)
[vpp.git] / test / test_nat.py
index 7ff3f85..79d2622 100644 (file)
@@ -7,10 +7,10 @@ import StringIO
 import random
 
 from framework import VppTestCase, VppTestRunner, running_extended_tests
 import random
 
 from framework import VppTestCase, VppTestRunner, running_extended_tests
-from vpp_ip_route import VppIpRoute, VppRoutePath, DpoProto
 from scapy.layers.inet import IP, TCP, UDP, ICMP
 from scapy.layers.inet import IPerror, TCPerror, UDPerror, ICMPerror
 from scapy.layers.inet import IP, TCP, UDP, ICMP
 from scapy.layers.inet import IPerror, TCPerror, UDPerror, ICMPerror
-from scapy.layers.inet6 import IPv6, ICMPv6EchoRequest, ICMPv6EchoReply
+from scapy.layers.inet6 import IPv6, ICMPv6EchoRequest, ICMPv6EchoReply, \
+    ICMPv6ND_NS, ICMPv6ND_NA, ICMPv6NDOptDstLLAddr
 from scapy.layers.inet6 import ICMPv6DestUnreach, IPerror6, IPv6ExtHdrFragment
 from scapy.layers.l2 import Ether, ARP, GRE
 from scapy.data import IP_PROTOS
 from scapy.layers.inet6 import ICMPv6DestUnreach, IPerror6, IPv6ExtHdrFragment
 from scapy.layers.l2 import Ether, ARP, GRE
 from scapy.data import IP_PROTOS
@@ -26,113 +26,174 @@ from util import mactobinary
 class MethodHolder(VppTestCase):
     """ NAT create capture and verify method holder """
 
 class MethodHolder(VppTestCase):
     """ NAT create capture and verify method holder """
 
-    @classmethod
-    def setUpClass(cls):
-        super(MethodHolder, cls).setUpClass()
+    def clear_nat44(self):
+        """
+        Clear NAT44 configuration.
+        """
+        if hasattr(self, 'pg7') and hasattr(self, 'pg8'):
+            # I found no elegant way to do this
+            self.vapi.ip_add_del_route(
+                dst_address=self.pg7.remote_ip4n,
+                dst_address_length=32,
+                next_hop_address=self.pg7.remote_ip4n,
+                next_hop_sw_if_index=self.pg7.sw_if_index,
+                is_add=0)
+            self.vapi.ip_add_del_route(
+                dst_address=self.pg8.remote_ip4n,
+                dst_address_length=32,
+                next_hop_address=self.pg8.remote_ip4n,
+                next_hop_sw_if_index=self.pg8.sw_if_index,
+                is_add=0)
 
 
-    def tearDown(self):
-        super(MethodHolder, self).tearDown()
+            for intf in [self.pg7, self.pg8]:
+                neighbors = self.vapi.ip_neighbor_dump(intf.sw_if_index)
+                for n in neighbors:
+                    self.vapi.ip_neighbor_add_del(intf.sw_if_index,
+                                                  n.mac_address,
+                                                  n.ip_address,
+                                                  is_add=0)
 
 
-    def check_ip_checksum(self, pkt):
-        """
-        Check IP checksum of the packet
+            if self.pg7.has_ip4_config:
+                self.pg7.unconfig_ip4()
 
 
-        :param pkt: Packet to check IP checksum
-        """
-        new = pkt.__class__(str(pkt))
-        del new['IP'].chksum
-        new = new.__class__(str(new))
-        self.assertEqual(new['IP'].chksum, pkt['IP'].chksum)
+        self.vapi.nat44_forwarding_enable_disable(0)
 
 
-    def check_tcp_checksum(self, pkt):
-        """
-        Check TCP checksum in IP packet
+        interfaces = self.vapi.nat44_interface_addr_dump()
+        for intf in interfaces:
+            self.vapi.nat44_add_interface_addr(intf.sw_if_index,
+                                               twice_nat=intf.twice_nat,
+                                               is_add=0)
 
 
-        :param pkt: Packet to check TCP checksum
-        """
-        new = pkt.__class__(str(pkt))
-        del new['TCP'].chksum
-        new = new.__class__(str(new))
-        self.assertEqual(new['TCP'].chksum, pkt['TCP'].chksum)
+        self.vapi.nat_ipfix(enable=0, src_port=self.ipfix_src_port,
+                            domain_id=self.ipfix_domain_id)
+        self.ipfix_src_port = 4739
+        self.ipfix_domain_id = 1
 
 
-    def check_udp_checksum(self, pkt):
-        """
-        Check UDP checksum in IP packet
+        interfaces = self.vapi.nat44_interface_dump()
+        for intf in interfaces:
+            if intf.is_inside > 1:
+                self.vapi.nat44_interface_add_del_feature(intf.sw_if_index,
+                                                          0,
+                                                          is_add=0)
+            self.vapi.nat44_interface_add_del_feature(intf.sw_if_index,
+                                                      intf.is_inside,
+                                                      is_add=0)
 
 
-        :param pkt: Packet to check UDP checksum
-        """
-        new = pkt.__class__(str(pkt))
-        del new['UDP'].chksum
-        new = new.__class__(str(new))
-        self.assertEqual(new['UDP'].chksum, pkt['UDP'].chksum)
+        interfaces = self.vapi.nat44_interface_output_feature_dump()
+        for intf in interfaces:
+            self.vapi.nat44_interface_add_del_output_feature(intf.sw_if_index,
+                                                             intf.is_inside,
+                                                             is_add=0)
 
 
-    def check_icmp_errror_embedded(self, pkt):
-        """
-        Check ICMP error embeded packet checksum
+        static_mappings = self.vapi.nat44_static_mapping_dump()
+        for sm in static_mappings:
+            self.vapi.nat44_add_del_static_mapping(
+                sm.local_ip_address,
+                sm.external_ip_address,
+                local_port=sm.local_port,
+                external_port=sm.external_port,
+                addr_only=sm.addr_only,
+                vrf_id=sm.vrf_id,
+                protocol=sm.protocol,
+                twice_nat=sm.twice_nat,
+                self_twice_nat=sm.self_twice_nat,
+                out2in_only=sm.out2in_only,
+                tag=sm.tag,
+                external_sw_if_index=sm.external_sw_if_index,
+                is_add=0)
 
 
-        :param pkt: Packet to check ICMP error embeded packet checksum
-        """
-        if pkt.haslayer(IPerror):
-            new = pkt.__class__(str(pkt))
-            del new['IPerror'].chksum
-            new = new.__class__(str(new))
-            self.assertEqual(new['IPerror'].chksum, pkt['IPerror'].chksum)
-
-        if pkt.haslayer(TCPerror):
-            new = pkt.__class__(str(pkt))
-            del new['TCPerror'].chksum
-            new = new.__class__(str(new))
-            self.assertEqual(new['TCPerror'].chksum, pkt['TCPerror'].chksum)
-
-        if pkt.haslayer(UDPerror):
-            if pkt['UDPerror'].chksum != 0:
-                new = pkt.__class__(str(pkt))
-                del new['UDPerror'].chksum
-                new = new.__class__(str(new))
-                self.assertEqual(new['UDPerror'].chksum,
-                                 pkt['UDPerror'].chksum)
-
-        if pkt.haslayer(ICMPerror):
-            del new['ICMPerror'].chksum
-            new = new.__class__(str(new))
-            self.assertEqual(new['ICMPerror'].chksum, pkt['ICMPerror'].chksum)
-
-    def check_icmp_checksum(self, pkt):
+        lb_static_mappings = self.vapi.nat44_lb_static_mapping_dump()
+        for lb_sm in lb_static_mappings:
+            self.vapi.nat44_add_del_lb_static_mapping(
+                lb_sm.external_addr,
+                lb_sm.external_port,
+                lb_sm.protocol,
+                twice_nat=lb_sm.twice_nat,
+                self_twice_nat=lb_sm.self_twice_nat,
+                out2in_only=lb_sm.out2in_only,
+                tag=lb_sm.tag,
+                is_add=0,
+                local_num=0,
+                locals=[])
+
+        identity_mappings = self.vapi.nat44_identity_mapping_dump()
+        for id_m in identity_mappings:
+            self.vapi.nat44_add_del_identity_mapping(
+                addr_only=id_m.addr_only,
+                ip=id_m.ip_address,
+                port=id_m.port,
+                sw_if_index=id_m.sw_if_index,
+                vrf_id=id_m.vrf_id,
+                protocol=id_m.protocol,
+                is_add=0)
+
+        adresses = self.vapi.nat44_address_dump()
+        for addr in adresses:
+            self.vapi.nat44_add_del_address_range(addr.ip_address,
+                                                  addr.ip_address,
+                                                  twice_nat=addr.twice_nat,
+                                                  is_add=0)
+
+        self.vapi.nat_set_reass()
+        self.vapi.nat_set_reass(is_ip6=1)
+        self.verify_no_nat44_user()
+        self.vapi.nat_set_timeouts()
+
+    def nat44_add_static_mapping(self, local_ip, external_ip='0.0.0.0',
+                                 local_port=0, external_port=0, vrf_id=0,
+                                 is_add=1, external_sw_if_index=0xFFFFFFFF,
+                                 proto=0, twice_nat=0, self_twice_nat=0,
+                                 out2in_only=0, tag=""):
         """
         """
-        Check ICMP checksum in IPv4 packet
+        Add/delete NAT44 static mapping
 
 
-        :param pkt: Packet to check ICMP checksum
+        :param local_ip: Local IP address
+        :param external_ip: External IP address
+        :param local_port: Local port number (Optional)
+        :param external_port: External port number (Optional)
+        :param vrf_id: VRF ID (Default 0)
+        :param is_add: 1 if add, 0 if delete (Default add)
+        :param external_sw_if_index: External interface instead of IP address
+        :param proto: IP protocol (Mandatory if port specified)
+        :param twice_nat: 1 if translate external host address and port
+        :param self_twice_nat: 1 if translate external host address and port
+                               whenever external host address equals
+                               local address of internal host
+        :param out2in_only: if 1 rule is matching only out2in direction
+        :param tag: Opaque string tag
         """
         """
-        new = pkt.__class__(str(pkt))
-        del new['ICMP'].chksum
-        new = new.__class__(str(new))
-        self.assertEqual(new['ICMP'].chksum, pkt['ICMP'].chksum)
-        if pkt.haslayer(IPerror):
-            self.check_icmp_errror_embedded(pkt)
-
-    def check_icmpv6_checksum(self, pkt):
+        addr_only = 1
+        if local_port and external_port:
+            addr_only = 0
+        l_ip = socket.inet_pton(socket.AF_INET, local_ip)
+        e_ip = socket.inet_pton(socket.AF_INET, external_ip)
+        self.vapi.nat44_add_del_static_mapping(
+            l_ip,
+            e_ip,
+            external_sw_if_index,
+            local_port,
+            external_port,
+            addr_only,
+            vrf_id,
+            proto,
+            twice_nat,
+            self_twice_nat,
+            out2in_only,
+            tag,
+            is_add)
+
+    def nat44_add_address(self, ip, is_add=1, vrf_id=0xFFFFFFFF, twice_nat=0):
         """
         """
-        Check ICMPv6 checksum in IPv4 packet
+        Add/delete NAT44 address
 
 
-        :param pkt: Packet to check ICMPv6 checksum
+        :param ip: IP address
+        :param is_add: 1 if add, 0 if delete (Default add)
+        :param twice_nat: twice NAT address for extenal hosts
         """
         """
-        new = pkt.__class__(str(pkt))
-        if pkt.haslayer(ICMPv6DestUnreach):
-            del new['ICMPv6DestUnreach'].cksum
-            new = new.__class__(str(new))
-            self.assertEqual(new['ICMPv6DestUnreach'].cksum,
-                             pkt['ICMPv6DestUnreach'].cksum)
-            self.check_icmp_errror_embedded(pkt)
-        if pkt.haslayer(ICMPv6EchoRequest):
-            del new['ICMPv6EchoRequest'].cksum
-            new = new.__class__(str(new))
-            self.assertEqual(new['ICMPv6EchoRequest'].cksum,
-                             pkt['ICMPv6EchoRequest'].cksum)
-        if pkt.haslayer(ICMPv6EchoReply):
-            del new['ICMPv6EchoReply'].cksum
-            new = new.__class__(str(new))
-            self.assertEqual(new['ICMPv6EchoReply'].cksum,
-                             pkt['ICMPv6EchoReply'].cksum)
+        nat_addr = socket.inet_pton(socket.AF_INET, ip)
+        self.vapi.nat44_add_del_address_range(nat_addr, nat_addr, is_add,
+                                              vrf_id=vrf_id,
+                                              twice_nat=twice_nat)
 
     def create_stream_in(self, in_if, out_if, dst_ip=None, ttl=64):
         """
 
     def create_stream_in(self, in_if, out_if, dst_ip=None, ttl=64):
         """
@@ -383,7 +444,7 @@ class MethodHolder(VppTestCase):
         for packet in capture:
             try:
                 if not is_ip6:
         for packet in capture:
             try:
                 if not is_ip6:
-                    self.check_ip_checksum(packet)
+                    self.assert_packet_checksums_valid(packet)
                 self.assertEqual(packet[IP46].src, nat_ip)
                 if dst_ip is not None:
                     self.assertEqual(packet[IP46].dst, dst_ip)
                 self.assertEqual(packet[IP46].src, nat_ip)
                 if dst_ip is not None:
                     self.assertEqual(packet[IP46].dst, dst_ip)
@@ -394,7 +455,7 @@ class MethodHolder(VppTestCase):
                         self.assertNotEqual(
                             packet[TCP].sport, self.tcp_port_in)
                     self.tcp_port_out = packet[TCP].sport
                         self.assertNotEqual(
                             packet[TCP].sport, self.tcp_port_in)
                     self.tcp_port_out = packet[TCP].sport
-                    self.check_tcp_checksum(packet)
+                    self.assert_packet_checksums_valid(packet)
                 elif packet.haslayer(UDP):
                     if same_port:
                         self.assertEqual(packet[UDP].sport, self.udp_port_in)
                 elif packet.haslayer(UDP):
                     if same_port:
                         self.assertEqual(packet[UDP].sport, self.udp_port_in)
@@ -408,10 +469,7 @@ class MethodHolder(VppTestCase):
                     else:
                         self.assertNotEqual(packet[ICMP46].id, self.icmp_id_in)
                     self.icmp_id_out = packet[ICMP46].id
                     else:
                         self.assertNotEqual(packet[ICMP46].id, self.icmp_id_in)
                     self.icmp_id_out = packet[ICMP46].id
-                    if is_ip6:
-                        self.check_icmpv6_checksum(packet)
-                    else:
-                        self.check_icmp_checksum(packet)
+                    self.assert_packet_checksums_valid(packet)
             except:
                 self.logger.error(ppp("Unexpected or invalid packet "
                                       "(outside network):", packet))
             except:
                 self.logger.error(ppp("Unexpected or invalid packet "
                                       "(outside network):", packet))
@@ -442,16 +500,14 @@ class MethodHolder(VppTestCase):
         self.assertEqual(packet_num, len(capture))
         for packet in capture:
             try:
         self.assertEqual(packet_num, len(capture))
         for packet in capture:
             try:
-                self.check_ip_checksum(packet)
+                self.assert_packet_checksums_valid(packet)
                 self.assertEqual(packet[IP].dst, in_if.remote_ip4)
                 if packet.haslayer(TCP):
                     self.assertEqual(packet[TCP].dport, self.tcp_port_in)
                 self.assertEqual(packet[IP].dst, in_if.remote_ip4)
                 if packet.haslayer(TCP):
                     self.assertEqual(packet[TCP].dport, self.tcp_port_in)
-                    self.check_tcp_checksum(packet)
                 elif packet.haslayer(UDP):
                     self.assertEqual(packet[UDP].dport, self.udp_port_in)
                 else:
                     self.assertEqual(packet[ICMP].id, self.icmp_id_in)
                 elif packet.haslayer(UDP):
                     self.assertEqual(packet[UDP].dport, self.udp_port_in)
                 else:
                     self.assertEqual(packet[ICMP].id, self.icmp_id_in)
-                    self.check_icmp_checksum(packet)
             except:
                 self.logger.error(ppp("Unexpected or invalid packet "
                                       "(inside network):", packet))
             except:
                 self.logger.error(ppp("Unexpected or invalid packet "
                                       "(inside network):", packet))
@@ -471,16 +527,14 @@ class MethodHolder(VppTestCase):
             try:
                 self.assertEqual(packet[IPv6].src, src_ip)
                 self.assertEqual(packet[IPv6].dst, dst_ip)
             try:
                 self.assertEqual(packet[IPv6].src, src_ip)
                 self.assertEqual(packet[IPv6].dst, dst_ip)
+                self.assert_packet_checksums_valid(packet)
                 if packet.haslayer(TCP):
                     self.assertEqual(packet[TCP].dport, self.tcp_port_in)
                 if packet.haslayer(TCP):
                     self.assertEqual(packet[TCP].dport, self.tcp_port_in)
-                    self.check_tcp_checksum(packet)
                 elif packet.haslayer(UDP):
                     self.assertEqual(packet[UDP].dport, self.udp_port_in)
                 elif packet.haslayer(UDP):
                     self.assertEqual(packet[UDP].dport, self.udp_port_in)
-                    self.check_udp_checksum(packet)
                 else:
                     self.assertEqual(packet[ICMPv6EchoReply].id,
                                      self.icmp_id_in)
                 else:
                     self.assertEqual(packet[ICMPv6EchoReply].id,
                                      self.icmp_id_in)
-                    self.check_icmpv6_checksum(packet)
             except:
                 self.logger.error(ppp("Unexpected or invalid packet "
                                       "(inside network):", packet))
             except:
                 self.logger.error(ppp("Unexpected or invalid packet "
                                       "(inside network):", packet))
@@ -655,7 +709,7 @@ class MethodHolder(VppTestCase):
         for p in frags:
             self.assertEqual(p[IP].src, src)
             self.assertEqual(p[IP].dst, dst)
         for p in frags:
             self.assertEqual(p[IP].src, src)
             self.assertEqual(p[IP].dst, dst)
-            self.check_ip_checksum(p)
+            self.assert_ip_checksum_valid(p)
             buffer.seek(p[IP].frag * 8)
             buffer.write(p[IP].payload)
         ip = frags[0].getlayer(IP)
             buffer.seek(p[IP].frag * 8)
             buffer.write(p[IP].payload)
         ip = frags[0].getlayer(IP)
@@ -663,7 +717,7 @@ class MethodHolder(VppTestCase):
                 proto=frags[0][IP].proto)
         if ip.proto == IP_PROTOS.tcp:
             p = (ip / TCP(buffer.getvalue()))
                 proto=frags[0][IP].proto)
         if ip.proto == IP_PROTOS.tcp:
             p = (ip / TCP(buffer.getvalue()))
-            self.check_tcp_checksum(p)
+            self.assert_tcp_checksum_valid(p)
         elif ip.proto == IP_PROTOS.udp:
             p = (ip / UDP(buffer.getvalue()))
         return p
         elif ip.proto == IP_PROTOS.udp:
             p = (ip / UDP(buffer.getvalue()))
         return p
@@ -688,11 +742,55 @@ class MethodHolder(VppTestCase):
                   nh=frags[0][IPv6ExtHdrFragment].nh)
         if ip.nh == IP_PROTOS.tcp:
             p = (ip / TCP(buffer.getvalue()))
                   nh=frags[0][IPv6ExtHdrFragment].nh)
         if ip.nh == IP_PROTOS.tcp:
             p = (ip / TCP(buffer.getvalue()))
-            self.check_tcp_checksum(p)
         elif ip.nh == IP_PROTOS.udp:
             p = (ip / UDP(buffer.getvalue()))
         elif ip.nh == IP_PROTOS.udp:
             p = (ip / UDP(buffer.getvalue()))
+        self.assert_packet_checksums_valid(p)
         return p
 
         return p
 
+    def initiate_tcp_session(self, in_if, out_if):
+        """
+        Initiates TCP session
+
+        :param in_if: Inside interface
+        :param out_if: Outside interface
+        """
+        try:
+            # SYN packet in->out
+            p = (Ether(src=in_if.remote_mac, dst=in_if.local_mac) /
+                 IP(src=in_if.remote_ip4, dst=out_if.remote_ip4) /
+                 TCP(sport=self.tcp_port_in, dport=self.tcp_external_port,
+                     flags="S"))
+            in_if.add_stream(p)
+            self.pg_enable_capture(self.pg_interfaces)
+            self.pg_start()
+            capture = out_if.get_capture(1)
+            p = capture[0]
+            self.tcp_port_out = p[TCP].sport
+
+            # SYN + ACK packet out->in
+            p = (Ether(src=out_if.remote_mac, dst=out_if.local_mac) /
+                 IP(src=out_if.remote_ip4, dst=self.nat_addr) /
+                 TCP(sport=self.tcp_external_port, dport=self.tcp_port_out,
+                     flags="SA"))
+            out_if.add_stream(p)
+            self.pg_enable_capture(self.pg_interfaces)
+            self.pg_start()
+            in_if.get_capture(1)
+
+            # ACK packet in->out
+            p = (Ether(src=in_if.remote_mac, dst=in_if.local_mac) /
+                 IP(src=in_if.remote_ip4, dst=out_if.remote_ip4) /
+                 TCP(sport=self.tcp_port_in, dport=self.tcp_external_port,
+                     flags="A"))
+            in_if.add_stream(p)
+            self.pg_enable_capture(self.pg_interfaces)
+            self.pg_start()
+            out_if.get_capture(1)
+
+        except:
+            self.logger.error("TCP 3 way handshake failed")
+            raise
+
     def verify_ipfix_nat44_ses(self, data):
         """
         Verify IPFIX NAT44 session create/delete event
     def verify_ipfix_nat44_ses(self, data):
         """
         Verify IPFIX NAT44 session create/delete event
@@ -891,6 +989,30 @@ class MethodHolder(VppTestCase):
         # postNAPTDestinationTransportPort
         self.assertEqual(struct.pack("!H", dst_port), record[228])
 
         # postNAPTDestinationTransportPort
         self.assertEqual(struct.pack("!H", dst_port), record[228])
 
+    def verify_no_nat44_user(self):
+        """ Verify that there is no NAT44 user """
+        users = self.vapi.nat44_user_dump()
+        self.assertEqual(len(users), 0)
+
+    def verify_ipfix_max_entries_per_user(self, data, limit, src_addr):
+        """
+        Verify IPFIX maximum entries per user exceeded event
+
+        :param data: Decoded IPFIX data records
+        :param limit: Number of maximum entries per user
+        :param src_addr: IPv4 source address
+        """
+        self.assertEqual(1, len(data))
+        record = data[0]
+        # natEvent
+        self.assertEqual(ord(record[230]), 13)
+        # natQuotaExceededEvent
+        self.assertEqual(struct.pack("I", 3), record[466])
+        # maxEntriesPerUser
+        self.assertEqual(struct.pack("I", limit), record[473])
+        # sourceIPv4Address
+        self.assertEqual(src_addr, record[8])
+
 
 class TestNAT44(MethodHolder):
     """ NAT44 Test Cases """
 
 class TestNAT44(MethodHolder):
     """ NAT44 Test Cases """
@@ -898,6 +1020,7 @@ class TestNAT44(MethodHolder):
     @classmethod
     def setUpClass(cls):
         super(TestNAT44, cls).setUpClass()
     @classmethod
     def setUpClass(cls):
         super(TestNAT44, cls).setUpClass()
+        cls.vapi.cli("set log class nat level debug")
 
         try:
             cls.tcp_port_in = 6303
 
         try:
             cls.tcp_port_in = 6303
@@ -910,6 +1033,7 @@ class TestNAT44(MethodHolder):
             cls.nat_addr_n = socket.inet_pton(socket.AF_INET, cls.nat_addr)
             cls.ipfix_src_port = 4739
             cls.ipfix_domain_id = 1
             cls.nat_addr_n = socket.inet_pton(socket.AF_INET, cls.nat_addr)
             cls.ipfix_src_port = 4739
             cls.ipfix_domain_id = 1
+            cls.tcp_external_port = 80
 
             cls.create_pg_interfaces(range(10))
             cls.interfaces = list(cls.pg_interfaces[0:4])
 
             cls.create_pg_interfaces(range(10))
             cls.interfaces = list(cls.pg_interfaces[0:4])
@@ -922,6 +1046,9 @@ class TestNAT44(MethodHolder):
             cls.pg0.generate_remote_hosts(3)
             cls.pg0.configure_ipv4_neighbors()
 
             cls.pg0.generate_remote_hosts(3)
             cls.pg0.configure_ipv4_neighbors()
 
+            cls.pg1.generate_remote_hosts(1)
+            cls.pg1.configure_ipv4_neighbors()
+
             cls.overlapping_interfaces = list(list(cls.pg_interfaces[4:7]))
             cls.vapi.ip_table_add_del(10, is_add=1)
             cls.vapi.ip_table_add_del(20, is_add=1)
             cls.overlapping_interfaces = list(list(cls.pg_interfaces[4:7]))
             cls.vapi.ip_table_add_del(10, is_add=1)
             cls.vapi.ip_table_add_del(20, is_add=1)
@@ -962,194 +1089,37 @@ class TestNAT44(MethodHolder):
             super(TestNAT44, cls).tearDownClass()
             raise
 
             super(TestNAT44, cls).tearDownClass()
             raise
 
-    def clear_nat44(self):
-        """
-        Clear NAT44 configuration.
-        """
-        # I found no elegant way to do this
-        self.vapi.ip_add_del_route(dst_address=self.pg7.remote_ip4n,
-                                   dst_address_length=32,
-                                   next_hop_address=self.pg7.remote_ip4n,
-                                   next_hop_sw_if_index=self.pg7.sw_if_index,
-                                   is_add=0)
-        self.vapi.ip_add_del_route(dst_address=self.pg8.remote_ip4n,
-                                   dst_address_length=32,
-                                   next_hop_address=self.pg8.remote_ip4n,
-                                   next_hop_sw_if_index=self.pg8.sw_if_index,
-                                   is_add=0)
-
-        for intf in [self.pg7, self.pg8]:
-            neighbors = self.vapi.ip_neighbor_dump(intf.sw_if_index)
-            for n in neighbors:
-                self.vapi.ip_neighbor_add_del(intf.sw_if_index,
-                                              n.mac_address,
-                                              n.ip_address,
-                                              is_add=0)
+    def test_dynamic(self):
+        """ NAT44 dynamic translation test """
 
 
-        if self.pg7.has_ip4_config:
-            self.pg7.unconfig_ip4()
+        self.nat44_add_address(self.nat_addr)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
 
 
-        self.vapi.nat44_forwarding_enable_disable(0)
+        # in2out
+        pkts = self.create_stream_in(self.pg0, self.pg1)
+        self.pg0.add_stream(pkts)
+        self.pg_enable_capture(self.pg_interfaces)
+        self.pg_start()
+        capture = self.pg1.get_capture(len(pkts))
+        self.verify_capture_out(capture)
 
 
-        interfaces = self.vapi.nat44_interface_addr_dump()
-        for intf in interfaces:
-            self.vapi.nat44_add_interface_addr(intf.sw_if_index,
-                                               twice_nat=intf.twice_nat,
-                                               is_add=0)
+        # out2in
+        pkts = self.create_stream_out(self.pg1)
+        self.pg1.add_stream(pkts)
+        self.pg_enable_capture(self.pg_interfaces)
+        self.pg_start()
+        capture = self.pg0.get_capture(len(pkts))
+        self.verify_capture_in(capture, self.pg0)
 
 
-        self.vapi.nat_ipfix(enable=0, src_port=self.ipfix_src_port,
-                            domain_id=self.ipfix_domain_id)
-        self.ipfix_src_port = 4739
-        self.ipfix_domain_id = 1
+    def test_dynamic_icmp_errors_in2out_ttl_1(self):
+        """ NAT44 handling of client packets with TTL=1 """
 
 
-        interfaces = self.vapi.nat44_interface_dump()
-        for intf in interfaces:
-            if intf.is_inside > 1:
-                self.vapi.nat44_interface_add_del_feature(intf.sw_if_index,
-                                                          0,
-                                                          is_add=0)
-            self.vapi.nat44_interface_add_del_feature(intf.sw_if_index,
-                                                      intf.is_inside,
-                                                      is_add=0)
-
-        interfaces = self.vapi.nat44_interface_output_feature_dump()
-        for intf in interfaces:
-            self.vapi.nat44_interface_add_del_output_feature(intf.sw_if_index,
-                                                             intf.is_inside,
-                                                             is_add=0)
-
-        static_mappings = self.vapi.nat44_static_mapping_dump()
-        for sm in static_mappings:
-            self.vapi.nat44_add_del_static_mapping(
-                sm.local_ip_address,
-                sm.external_ip_address,
-                local_port=sm.local_port,
-                external_port=sm.external_port,
-                addr_only=sm.addr_only,
-                vrf_id=sm.vrf_id,
-                protocol=sm.protocol,
-                twice_nat=sm.twice_nat,
-                out2in_only=sm.out2in_only,
-                tag=sm.tag,
-                is_add=0)
-
-        lb_static_mappings = self.vapi.nat44_lb_static_mapping_dump()
-        for lb_sm in lb_static_mappings:
-            self.vapi.nat44_add_del_lb_static_mapping(
-                lb_sm.external_addr,
-                lb_sm.external_port,
-                lb_sm.protocol,
-                vrf_id=lb_sm.vrf_id,
-                twice_nat=lb_sm.twice_nat,
-                out2in_only=lb_sm.out2in_only,
-                tag=lb_sm.tag,
-                is_add=0,
-                local_num=0,
-                locals=[])
-
-        identity_mappings = self.vapi.nat44_identity_mapping_dump()
-        for id_m in identity_mappings:
-            self.vapi.nat44_add_del_identity_mapping(
-                addr_only=id_m.addr_only,
-                ip=id_m.ip_address,
-                port=id_m.port,
-                sw_if_index=id_m.sw_if_index,
-                vrf_id=id_m.vrf_id,
-                protocol=id_m.protocol,
-                is_add=0)
-
-        adresses = self.vapi.nat44_address_dump()
-        for addr in adresses:
-            self.vapi.nat44_add_del_address_range(addr.ip_address,
-                                                  addr.ip_address,
-                                                  twice_nat=addr.twice_nat,
-                                                  is_add=0)
-
-        self.vapi.nat_set_reass()
-        self.vapi.nat_set_reass(is_ip6=1)
-
-    def nat44_add_static_mapping(self, local_ip, external_ip='0.0.0.0',
-                                 local_port=0, external_port=0, vrf_id=0,
-                                 is_add=1, external_sw_if_index=0xFFFFFFFF,
-                                 proto=0, twice_nat=0, out2in_only=0, tag=""):
-        """
-        Add/delete NAT44 static mapping
-
-        :param local_ip: Local IP address
-        :param external_ip: External IP address
-        :param local_port: Local port number (Optional)
-        :param external_port: External port number (Optional)
-        :param vrf_id: VRF ID (Default 0)
-        :param is_add: 1 if add, 0 if delete (Default add)
-        :param external_sw_if_index: External interface instead of IP address
-        :param proto: IP protocol (Mandatory if port specified)
-        :param twice_nat: 1 if translate external host address and port
-        :param out2in_only: if 1 rule is matching only out2in direction
-        :param tag: Opaque string tag
-        """
-        addr_only = 1
-        if local_port and external_port:
-            addr_only = 0
-        l_ip = socket.inet_pton(socket.AF_INET, local_ip)
-        e_ip = socket.inet_pton(socket.AF_INET, external_ip)
-        self.vapi.nat44_add_del_static_mapping(
-            l_ip,
-            e_ip,
-            external_sw_if_index,
-            local_port,
-            external_port,
-            addr_only,
-            vrf_id,
-            proto,
-            twice_nat,
-            out2in_only,
-            tag,
-            is_add)
-
-    def nat44_add_address(self, ip, is_add=1, vrf_id=0xFFFFFFFF, twice_nat=0):
-        """
-        Add/delete NAT44 address
-
-        :param ip: IP address
-        :param is_add: 1 if add, 0 if delete (Default add)
-        :param twice_nat: twice NAT address for extenal hosts
-        """
-        nat_addr = socket.inet_pton(socket.AF_INET, ip)
-        self.vapi.nat44_add_del_address_range(nat_addr, nat_addr, is_add,
-                                              vrf_id=vrf_id,
-                                              twice_nat=twice_nat)
-
-    def test_dynamic(self):
-        """ NAT44 dynamic translation test """
-
-        self.nat44_add_address(self.nat_addr)
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
-                                                  is_inside=0)
-
-        # in2out
-        pkts = self.create_stream_in(self.pg0, self.pg1)
-        self.pg0.add_stream(pkts)
-        self.pg_enable_capture(self.pg_interfaces)
-        self.pg_start()
-        capture = self.pg1.get_capture(len(pkts))
-        self.verify_capture_out(capture)
-
-        # out2in
-        pkts = self.create_stream_out(self.pg1)
-        self.pg1.add_stream(pkts)
-        self.pg_enable_capture(self.pg_interfaces)
-        self.pg_start()
-        capture = self.pg0.get_capture(len(pkts))
-        self.verify_capture_in(capture, self.pg0)
-
-    def test_dynamic_icmp_errors_in2out_ttl_1(self):
-        """ NAT44 handling of client packets with TTL=1 """
-
-        self.nat44_add_address(self.nat_addr)
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
-                                                  is_inside=0)
+        self.nat44_add_address(self.nat_addr)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
 
         # Client side - generate traffic
         pkts = self.create_stream_in(self.pg0, self.pg1, ttl=1)
 
         # Client side - generate traffic
         pkts = self.create_stream_in(self.pg0, self.pg1, ttl=1)
@@ -1322,7 +1292,7 @@ class TestNAT44(MethodHolder):
                                                external_ip=alias_ip)
 
         try:
                                                external_ip=alias_ip)
 
         try:
-            # in2out - static mapping match
+            # static mapping match
 
             pkts = self.create_stream_out(self.pg1)
             self.pg1.add_stream(pkts)
 
             pkts = self.create_stream_out(self.pg1)
             self.pg1.add_stream(pkts)
@@ -1338,7 +1308,7 @@ class TestNAT44(MethodHolder):
             capture = self.pg1.get_capture(len(pkts))
             self.verify_capture_out(capture, same_port=True)
 
             capture = self.pg1.get_capture(len(pkts))
             self.verify_capture_out(capture, same_port=True)
 
-            # in2out - no static mapping match
+            # no static mapping match
 
             host0 = self.pg0.remote_hosts[0]
             self.pg0.remote_hosts[0] = self.pg0.remote_hosts[1]
 
             host0 = self.pg0.remote_hosts[0]
             self.pg0.remote_hosts[0] = self.pg0.remote_hosts[1]
@@ -1510,552 +1480,216 @@ class TestNAT44(MethodHolder):
         capture = self.pg1.get_capture(len(pkts))
         self.verify_capture_out(capture)
 
         capture = self.pg1.get_capture(len(pkts))
         self.verify_capture_out(capture)
 
-    def test_static_with_port_out2(self):
-        """ 1:1 NAPT symmetrical rule """
+    def test_static_vrf_aware(self):
+        """ 1:1 NAT VRF awareness """
 
 
-        external_port = 80
-        local_port = 8080
+        nat_ip1 = "10.0.0.30"
+        nat_ip2 = "10.0.0.40"
+        self.tcp_port_out = 6303
+        self.udp_port_out = 6304
+        self.icmp_id_out = 6305
 
 
-        self.vapi.nat44_forwarding_enable_disable(1)
-        self.nat44_add_static_mapping(self.pg0.remote_ip4, self.nat_addr,
-                                      local_port, external_port,
-                                      proto=IP_PROTOS.tcp, out2in_only=1)
+        self.nat44_add_static_mapping(self.pg4.remote_ip4, nat_ip1,
+                                      vrf_id=10)
+        self.nat44_add_static_mapping(self.pg0.remote_ip4, nat_ip2,
+                                      vrf_id=10)
+        self.vapi.nat44_interface_add_del_feature(self.pg3.sw_if_index,
+                                                  is_inside=0)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg4.sw_if_index)
+
+        # inside interface VRF match NAT44 static mapping VRF
+        pkts = self.create_stream_in(self.pg4, self.pg3)
+        self.pg4.add_stream(pkts)
+        self.pg_enable_capture(self.pg_interfaces)
+        self.pg_start()
+        capture = self.pg3.get_capture(len(pkts))
+        self.verify_capture_out(capture, nat_ip1, True)
+
+        # inside interface VRF don't match NAT44 static mapping VRF (packets
+        # are dropped)
+        pkts = self.create_stream_in(self.pg0, self.pg3)
+        self.pg0.add_stream(pkts)
+        self.pg_enable_capture(self.pg_interfaces)
+        self.pg_start()
+        self.pg3.assert_nothing_captured()
+
+    def test_dynamic_to_static(self):
+        """ Switch from dynamic translation to 1:1NAT """
+        nat_ip = "10.0.0.10"
+        self.tcp_port_out = 6303
+        self.udp_port_out = 6304
+        self.icmp_id_out = 6305
+
+        self.nat44_add_address(self.nat_addr)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
+
+        # dynamic
+        pkts = self.create_stream_in(self.pg0, self.pg1)
+        self.pg0.add_stream(pkts)
+        self.pg_enable_capture(self.pg_interfaces)
+        self.pg_start()
+        capture = self.pg1.get_capture(len(pkts))
+        self.verify_capture_out(capture)
+
+        # 1:1NAT
+        self.nat44_add_static_mapping(self.pg0.remote_ip4, nat_ip)
+        sessions = self.vapi.nat44_user_session_dump(self.pg0.remote_ip4n, 0)
+        self.assertEqual(len(sessions), 0)
+        pkts = self.create_stream_in(self.pg0, self.pg1)
+        self.pg0.add_stream(pkts)
+        self.pg_enable_capture(self.pg_interfaces)
+        self.pg_start()
+        capture = self.pg1.get_capture(len(pkts))
+        self.verify_capture_out(capture, nat_ip, True)
+
+    def test_identity_nat(self):
+        """ Identity NAT """
+
+        self.vapi.nat44_add_del_identity_mapping(ip=self.pg0.remote_ip4n)
         self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
         self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
                                                   is_inside=0)
 
         self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
         self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
                                                   is_inside=0)
 
-        # from client to service
         p = (Ether(src=self.pg1.remote_mac, dst=self.pg1.local_mac) /
         p = (Ether(src=self.pg1.remote_mac, dst=self.pg1.local_mac) /
-             IP(src=self.pg1.remote_ip4, dst=self.nat_addr) /
-             TCP(sport=12345, dport=external_port))
+             IP(src=self.pg1.remote_ip4, dst=self.pg0.remote_ip4) /
+             TCP(sport=12345, dport=56789))
         self.pg1.add_stream(p)
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
         capture = self.pg0.get_capture(1)
         p = capture[0]
         self.pg1.add_stream(p)
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
         capture = self.pg0.get_capture(1)
         p = capture[0]
-        server = None
         try:
             ip = p[IP]
             tcp = p[TCP]
             self.assertEqual(ip.dst, self.pg0.remote_ip4)
         try:
             ip = p[IP]
             tcp = p[TCP]
             self.assertEqual(ip.dst, self.pg0.remote_ip4)
-            self.assertEqual(tcp.dport, local_port)
-            self.check_tcp_checksum(p)
-            self.check_ip_checksum(p)
+            self.assertEqual(ip.src, self.pg1.remote_ip4)
+            self.assertEqual(tcp.dport, 56789)
+            self.assertEqual(tcp.sport, 12345)
+            self.assert_packet_checksums_valid(p)
         except:
             self.logger.error(ppp("Unexpected or invalid packet:", p))
             raise
 
         except:
             self.logger.error(ppp("Unexpected or invalid packet:", p))
             raise
 
-        # ICMP error
-        p = (Ether(dst=self.pg0.local_mac, src=self.pg0.remote_mac) /
-             IP(src=self.pg0.remote_ip4, dst=self.pg1.remote_ip4) /
-             ICMP(type=11) / capture[0][IP])
-        self.pg0.add_stream(p)
-        self.pg_enable_capture(self.pg_interfaces)
-        self.pg_start()
-        capture = self.pg1.get_capture(1)
-        p = capture[0]
-        try:
-            self.assertEqual(p[IP].src, self.nat_addr)
-            inner = p[IPerror]
-            self.assertEqual(inner.dst, self.nat_addr)
-            self.assertEqual(inner[TCPerror].dport, external_port)
-        except:
-            self.logger.error(ppp("Unexpected or invalid packet:", p))
-            raise
+    def test_multiple_inside_interfaces(self):
+        """ NAT44 multiple non-overlapping address space inside interfaces """
 
 
-        # from service back to client
-        p = (Ether(src=self.pg0.remote_mac, dst=self.pg0.local_mac) /
-             IP(src=self.pg0.remote_ip4, dst=self.pg1.remote_ip4) /
-             TCP(sport=local_port, dport=12345))
-        self.pg0.add_stream(p)
+        self.nat44_add_address(self.nat_addr)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg3.sw_if_index,
+                                                  is_inside=0)
+
+        # between two NAT44 inside interfaces (no translation)
+        pkts = self.create_stream_in(self.pg0, self.pg1)
+        self.pg0.add_stream(pkts)
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
-        capture = self.pg1.get_capture(1)
-        p = capture[0]
-        try:
-            ip = p[IP]
-            tcp = p[TCP]
-            self.assertEqual(ip.src, self.nat_addr)
-            self.assertEqual(tcp.sport, external_port)
-            self.check_tcp_checksum(p)
-            self.check_ip_checksum(p)
-        except:
-            self.logger.error(ppp("Unexpected or invalid packet:", p))
-            raise
+        capture = self.pg1.get_capture(len(pkts))
+        self.verify_capture_no_translation(capture, self.pg0, self.pg1)
 
 
-        # ICMP error
-        p = (Ether(dst=self.pg1.local_mac, src=self.pg1.remote_mac) /
-             IP(src=self.pg1.remote_ip4, dst=self.nat_addr) /
-             ICMP(type=11) / capture[0][IP])
-        self.pg1.add_stream(p)
+        # from NAT44 inside to interface without NAT44 feature (no translation)
+        pkts = self.create_stream_in(self.pg0, self.pg2)
+        self.pg0.add_stream(pkts)
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
-        capture = self.pg0.get_capture(1)
-        p = capture[0]
-        try:
-            self.assertEqual(p[IP].dst, self.pg0.remote_ip4)
-            inner = p[IPerror]
-            self.assertEqual(inner.src, self.pg0.remote_ip4)
-            self.assertEqual(inner[TCPerror].sport, local_port)
-        except:
-            self.logger.error(ppp("Unexpected or invalid packet:", p))
-            raise
+        capture = self.pg2.get_capture(len(pkts))
+        self.verify_capture_no_translation(capture, self.pg0, self.pg2)
 
 
-        # from client to server (no translation)
-        p = (Ether(src=self.pg1.remote_mac, dst=self.pg1.local_mac) /
-             IP(src=self.pg1.remote_ip4, dst=self.pg0.remote_ip4) /
-             TCP(sport=12346, dport=local_port))
-        self.pg1.add_stream(p)
+        # in2out 1st interface
+        pkts = self.create_stream_in(self.pg0, self.pg3)
+        self.pg0.add_stream(pkts)
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
-        capture = self.pg0.get_capture(1)
-        p = capture[0]
-        server = None
-        try:
-            ip = p[IP]
-            tcp = p[TCP]
-            self.assertEqual(ip.dst, self.pg0.remote_ip4)
-            self.assertEqual(tcp.dport, local_port)
-            self.check_tcp_checksum(p)
-            self.check_ip_checksum(p)
-        except:
-            self.logger.error(ppp("Unexpected or invalid packet:", p))
-            raise
+        capture = self.pg3.get_capture(len(pkts))
+        self.verify_capture_out(capture)
 
 
-        # from service back to client (no translation)
-        p = (Ether(src=self.pg0.remote_mac, dst=self.pg0.local_mac) /
-             IP(src=self.pg0.remote_ip4, dst=self.pg1.remote_ip4) /
-             TCP(sport=local_port, dport=12346))
-        self.pg0.add_stream(p)
+        # out2in 1st interface
+        pkts = self.create_stream_out(self.pg3)
+        self.pg3.add_stream(pkts)
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
-        capture = self.pg1.get_capture(1)
-        p = capture[0]
-        try:
-            ip = p[IP]
-            tcp = p[TCP]
-            self.assertEqual(ip.src, self.pg0.remote_ip4)
-            self.assertEqual(tcp.sport, local_port)
-            self.check_tcp_checksum(p)
-            self.check_ip_checksum(p)
-        except:
-            self.logger.error(ppp("Unexpected or invalid packet:", p))
-            raise
-
-    def test_static_vrf_aware(self):
-        """ 1:1 NAT VRF awareness """
-
-        nat_ip1 = "10.0.0.30"
-        nat_ip2 = "10.0.0.40"
-        self.tcp_port_out = 6303
-        self.udp_port_out = 6304
-        self.icmp_id_out = 6305
-
-        self.nat44_add_static_mapping(self.pg4.remote_ip4, nat_ip1,
-                                      vrf_id=10)
-        self.nat44_add_static_mapping(self.pg0.remote_ip4, nat_ip2,
-                                      vrf_id=10)
-        self.vapi.nat44_interface_add_del_feature(self.pg3.sw_if_index,
-                                                  is_inside=0)
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
-        self.vapi.nat44_interface_add_del_feature(self.pg4.sw_if_index)
+        capture = self.pg0.get_capture(len(pkts))
+        self.verify_capture_in(capture, self.pg0)
 
 
-        # inside interface VRF match NAT44 static mapping VRF
-        pkts = self.create_stream_in(self.pg4, self.pg3)
-        self.pg4.add_stream(pkts)
+        # in2out 2nd interface
+        pkts = self.create_stream_in(self.pg1, self.pg3)
+        self.pg1.add_stream(pkts)
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
         capture = self.pg3.get_capture(len(pkts))
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
         capture = self.pg3.get_capture(len(pkts))
-        self.verify_capture_out(capture, nat_ip1, True)
+        self.verify_capture_out(capture)
 
 
-        # inside interface VRF don't match NAT44 static mapping VRF (packets
-        # are dropped)
-        pkts = self.create_stream_in(self.pg0, self.pg3)
-        self.pg0.add_stream(pkts)
+        # out2in 2nd interface
+        pkts = self.create_stream_out(self.pg3)
+        self.pg3.add_stream(pkts)
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
-        self.pg3.assert_nothing_captured()
+        capture = self.pg1.get_capture(len(pkts))
+        self.verify_capture_in(capture, self.pg1)
 
 
-    def test_dynamic_to_static(self):
-        """ Switch from dynamic translation to 1:1NAT """
-        nat_ip = "10.0.0.10"
-        self.tcp_port_out = 6303
-        self.udp_port_out = 6304
-        self.icmp_id_out = 6305
+    def test_inside_overlapping_interfaces(self):
+        """ NAT44 multiple inside interfaces with overlapping address space """
 
 
+        static_nat_ip = "10.0.0.10"
         self.nat44_add_address(self.nat_addr)
         self.nat44_add_address(self.nat_addr)
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+        self.vapi.nat44_interface_add_del_feature(self.pg3.sw_if_index,
                                                   is_inside=0)
                                                   is_inside=0)
+        self.vapi.nat44_interface_add_del_feature(self.pg4.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg5.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg6.sw_if_index)
+        self.nat44_add_static_mapping(self.pg6.remote_ip4, static_nat_ip,
+                                      vrf_id=20)
 
 
-        # dynamic
-        pkts = self.create_stream_in(self.pg0, self.pg1)
-        self.pg0.add_stream(pkts)
-        self.pg_enable_capture(self.pg_interfaces)
-        self.pg_start()
-        capture = self.pg1.get_capture(len(pkts))
-        self.verify_capture_out(capture)
-
-        # 1:1NAT
-        self.nat44_add_static_mapping(self.pg0.remote_ip4, nat_ip)
-        sessions = self.vapi.nat44_user_session_dump(self.pg0.remote_ip4n, 0)
-        self.assertEqual(len(sessions), 0)
-        pkts = self.create_stream_in(self.pg0, self.pg1)
-        self.pg0.add_stream(pkts)
+        # between NAT44 inside interfaces with same VRF (no translation)
+        pkts = self.create_stream_in(self.pg4, self.pg5)
+        self.pg4.add_stream(pkts)
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
-        capture = self.pg1.get_capture(len(pkts))
-        self.verify_capture_out(capture, nat_ip, True)
-
-    def test_identity_nat(self):
-        """ Identity NAT """
-
-        self.vapi.nat44_add_del_identity_mapping(ip=self.pg0.remote_ip4n)
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
-                                                  is_inside=0)
+        capture = self.pg5.get_capture(len(pkts))
+        self.verify_capture_no_translation(capture, self.pg4, self.pg5)
 
 
-        p = (Ether(src=self.pg1.remote_mac, dst=self.pg1.local_mac) /
-             IP(src=self.pg1.remote_ip4, dst=self.pg0.remote_ip4) /
-             TCP(sport=12345, dport=56789))
-        self.pg1.add_stream(p)
+        # between NAT44 inside interfaces with different VRF (hairpinning)
+        p = (Ether(src=self.pg4.remote_mac, dst=self.pg4.local_mac) /
+             IP(src=self.pg4.remote_ip4, dst=static_nat_ip) /
+             TCP(sport=1234, dport=5678))
+        self.pg4.add_stream(p)
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
-        capture = self.pg0.get_capture(1)
+        capture = self.pg6.get_capture(1)
         p = capture[0]
         try:
             ip = p[IP]
             tcp = p[TCP]
         p = capture[0]
         try:
             ip = p[IP]
             tcp = p[TCP]
-            self.assertEqual(ip.dst, self.pg0.remote_ip4)
-            self.assertEqual(ip.src, self.pg1.remote_ip4)
-            self.assertEqual(tcp.dport, 56789)
-            self.assertEqual(tcp.sport, 12345)
-            self.check_tcp_checksum(p)
-            self.check_ip_checksum(p)
+            self.assertEqual(ip.src, self.nat_addr)
+            self.assertEqual(ip.dst, self.pg6.remote_ip4)
+            self.assertNotEqual(tcp.sport, 1234)
+            self.assertEqual(tcp.dport, 5678)
         except:
             self.logger.error(ppp("Unexpected or invalid packet:", p))
             raise
 
         except:
             self.logger.error(ppp("Unexpected or invalid packet:", p))
             raise
 
-    def test_static_lb(self):
-        """ NAT44 local service load balancing """
-        external_addr_n = socket.inet_pton(socket.AF_INET, self.nat_addr)
-        external_port = 80
-        local_port = 8080
-        server1 = self.pg0.remote_hosts[0]
-        server2 = self.pg0.remote_hosts[1]
-
-        locals = [{'addr': server1.ip4n,
-                   'port': local_port,
-                   'probability': 70},
-                  {'addr': server2.ip4n,
-                   'port': local_port,
-                   'probability': 30}]
-
-        self.nat44_add_address(self.nat_addr)
-        self.vapi.nat44_add_del_lb_static_mapping(external_addr_n,
-                                                  external_port,
-                                                  IP_PROTOS.tcp,
-                                                  local_num=len(locals),
-                                                  locals=locals)
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
-                                                  is_inside=0)
-
-        # from client to service
-        p = (Ether(src=self.pg1.remote_mac, dst=self.pg1.local_mac) /
-             IP(src=self.pg1.remote_ip4, dst=self.nat_addr) /
-             TCP(sport=12345, dport=external_port))
-        self.pg1.add_stream(p)
+        # in2out 1st interface
+        pkts = self.create_stream_in(self.pg4, self.pg3)
+        self.pg4.add_stream(pkts)
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
-        capture = self.pg0.get_capture(1)
-        p = capture[0]
-        server = None
-        try:
-            ip = p[IP]
-            tcp = p[TCP]
-            self.assertIn(ip.dst, [server1.ip4, server2.ip4])
-            if ip.dst == server1.ip4:
-                server = server1
-            else:
-                server = server2
-            self.assertEqual(tcp.dport, local_port)
-            self.check_tcp_checksum(p)
-            self.check_ip_checksum(p)
-        except:
-            self.logger.error(ppp("Unexpected or invalid packet:", p))
-            raise
+        capture = self.pg3.get_capture(len(pkts))
+        self.verify_capture_out(capture)
 
 
-        # from service back to client
-        p = (Ether(src=server.mac, dst=self.pg0.local_mac) /
-             IP(src=server.ip4, dst=self.pg1.remote_ip4) /
-             TCP(sport=local_port, dport=12345))
-        self.pg0.add_stream(p)
+        # out2in 1st interface
+        pkts = self.create_stream_out(self.pg3)
+        self.pg3.add_stream(pkts)
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
-        capture = self.pg1.get_capture(1)
-        p = capture[0]
-        try:
-            ip = p[IP]
-            tcp = p[TCP]
-            self.assertEqual(ip.src, self.nat_addr)
-            self.assertEqual(tcp.sport, external_port)
-            self.check_tcp_checksum(p)
-            self.check_ip_checksum(p)
-        except:
-            self.logger.error(ppp("Unexpected or invalid packet:", p))
-            raise
+        capture = self.pg4.get_capture(len(pkts))
+        self.verify_capture_in(capture, self.pg4)
 
 
-        # multiple clients
-        server1_n = 0
-        server2_n = 0
-        clients = ip4_range(self.pg1.remote_ip4, 10, 20)
-        pkts = []
-        for client in clients:
-            p = (Ether(src=self.pg1.remote_mac, dst=self.pg1.local_mac) /
-                 IP(src=client, dst=self.nat_addr) /
-                 TCP(sport=12345, dport=external_port))
-            pkts.append(p)
-        self.pg1.add_stream(pkts)
-        self.pg_enable_capture(self.pg_interfaces)
-        self.pg_start()
-        capture = self.pg0.get_capture(len(pkts))
-        for p in capture:
-            if p[IP].dst == server1.ip4:
-                server1_n += 1
-            else:
-                server2_n += 1
-        self.assertTrue(server1_n > server2_n)
-
-    def test_static_lb_2(self):
-        """ NAT44 local service load balancing (asymmetrical rule) """
-        external_addr_n = socket.inet_pton(socket.AF_INET, self.nat_addr)
-        external_port = 80
-        local_port = 8080
-        server1 = self.pg0.remote_hosts[0]
-        server2 = self.pg0.remote_hosts[1]
-
-        locals = [{'addr': server1.ip4n,
-                   'port': local_port,
-                   'probability': 70},
-                  {'addr': server2.ip4n,
-                   'port': local_port,
-                   'probability': 30}]
-
-        self.vapi.nat44_forwarding_enable_disable(1)
-        self.vapi.nat44_add_del_lb_static_mapping(external_addr_n,
-                                                  external_port,
-                                                  IP_PROTOS.tcp,
-                                                  out2in_only=1,
-                                                  local_num=len(locals),
-                                                  locals=locals)
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
-                                                  is_inside=0)
-
-        # from client to service
-        p = (Ether(src=self.pg1.remote_mac, dst=self.pg1.local_mac) /
-             IP(src=self.pg1.remote_ip4, dst=self.nat_addr) /
-             TCP(sport=12345, dport=external_port))
-        self.pg1.add_stream(p)
-        self.pg_enable_capture(self.pg_interfaces)
-        self.pg_start()
-        capture = self.pg0.get_capture(1)
-        p = capture[0]
-        server = None
-        try:
-            ip = p[IP]
-            tcp = p[TCP]
-            self.assertIn(ip.dst, [server1.ip4, server2.ip4])
-            if ip.dst == server1.ip4:
-                server = server1
-            else:
-                server = server2
-            self.assertEqual(tcp.dport, local_port)
-            self.check_tcp_checksum(p)
-            self.check_ip_checksum(p)
-        except:
-            self.logger.error(ppp("Unexpected or invalid packet:", p))
-            raise
-
-        # from service back to client
-        p = (Ether(src=server.mac, dst=self.pg0.local_mac) /
-             IP(src=server.ip4, dst=self.pg1.remote_ip4) /
-             TCP(sport=local_port, dport=12345))
-        self.pg0.add_stream(p)
-        self.pg_enable_capture(self.pg_interfaces)
-        self.pg_start()
-        capture = self.pg1.get_capture(1)
-        p = capture[0]
-        try:
-            ip = p[IP]
-            tcp = p[TCP]
-            self.assertEqual(ip.src, self.nat_addr)
-            self.assertEqual(tcp.sport, external_port)
-            self.check_tcp_checksum(p)
-            self.check_ip_checksum(p)
-        except:
-            self.logger.error(ppp("Unexpected or invalid packet:", p))
-            raise
-
-        # from client to server (no translation)
-        p = (Ether(src=self.pg1.remote_mac, dst=self.pg1.local_mac) /
-             IP(src=self.pg1.remote_ip4, dst=server1.ip4) /
-             TCP(sport=12346, dport=local_port))
-        self.pg1.add_stream(p)
-        self.pg_enable_capture(self.pg_interfaces)
-        self.pg_start()
-        capture = self.pg0.get_capture(1)
-        p = capture[0]
-        server = None
-        try:
-            ip = p[IP]
-            tcp = p[TCP]
-            self.assertEqual(ip.dst, server1.ip4)
-            self.assertEqual(tcp.dport, local_port)
-            self.check_tcp_checksum(p)
-            self.check_ip_checksum(p)
-        except:
-            self.logger.error(ppp("Unexpected or invalid packet:", p))
-            raise
-
-        # from service back to client (no translation)
-        p = (Ether(src=server1.mac, dst=self.pg0.local_mac) /
-             IP(src=server1.ip4, dst=self.pg1.remote_ip4) /
-             TCP(sport=local_port, dport=12346))
-        self.pg0.add_stream(p)
-        self.pg_enable_capture(self.pg_interfaces)
-        self.pg_start()
-        capture = self.pg1.get_capture(1)
-        p = capture[0]
-        try:
-            ip = p[IP]
-            tcp = p[TCP]
-            self.assertEqual(ip.src, server1.ip4)
-            self.assertEqual(tcp.sport, local_port)
-            self.check_tcp_checksum(p)
-            self.check_ip_checksum(p)
-        except:
-            self.logger.error(ppp("Unexpected or invalid packet:", p))
-            raise
-
-    def test_multiple_inside_interfaces(self):
-        """ NAT44 multiple non-overlapping address space inside interfaces """
-
-        self.nat44_add_address(self.nat_addr)
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index)
-        self.vapi.nat44_interface_add_del_feature(self.pg3.sw_if_index,
-                                                  is_inside=0)
-
-        # between two NAT44 inside interfaces (no translation)
-        pkts = self.create_stream_in(self.pg0, self.pg1)
-        self.pg0.add_stream(pkts)
-        self.pg_enable_capture(self.pg_interfaces)
-        self.pg_start()
-        capture = self.pg1.get_capture(len(pkts))
-        self.verify_capture_no_translation(capture, self.pg0, self.pg1)
-
-        # from NAT44 inside to interface without NAT44 feature (no translation)
-        pkts = self.create_stream_in(self.pg0, self.pg2)
-        self.pg0.add_stream(pkts)
-        self.pg_enable_capture(self.pg_interfaces)
-        self.pg_start()
-        capture = self.pg2.get_capture(len(pkts))
-        self.verify_capture_no_translation(capture, self.pg0, self.pg2)
-
-        # in2out 1st interface
-        pkts = self.create_stream_in(self.pg0, self.pg3)
-        self.pg0.add_stream(pkts)
-        self.pg_enable_capture(self.pg_interfaces)
-        self.pg_start()
-        capture = self.pg3.get_capture(len(pkts))
-        self.verify_capture_out(capture)
-
-        # out2in 1st interface
-        pkts = self.create_stream_out(self.pg3)
-        self.pg3.add_stream(pkts)
-        self.pg_enable_capture(self.pg_interfaces)
-        self.pg_start()
-        capture = self.pg0.get_capture(len(pkts))
-        self.verify_capture_in(capture, self.pg0)
-
-        # in2out 2nd interface
-        pkts = self.create_stream_in(self.pg1, self.pg3)
-        self.pg1.add_stream(pkts)
-        self.pg_enable_capture(self.pg_interfaces)
-        self.pg_start()
-        capture = self.pg3.get_capture(len(pkts))
-        self.verify_capture_out(capture)
-
-        # out2in 2nd interface
-        pkts = self.create_stream_out(self.pg3)
-        self.pg3.add_stream(pkts)
-        self.pg_enable_capture(self.pg_interfaces)
-        self.pg_start()
-        capture = self.pg1.get_capture(len(pkts))
-        self.verify_capture_in(capture, self.pg1)
-
-    def test_inside_overlapping_interfaces(self):
-        """ NAT44 multiple inside interfaces with overlapping address space """
-
-        static_nat_ip = "10.0.0.10"
-        self.nat44_add_address(self.nat_addr)
-        self.vapi.nat44_interface_add_del_feature(self.pg3.sw_if_index,
-                                                  is_inside=0)
-        self.vapi.nat44_interface_add_del_feature(self.pg4.sw_if_index)
-        self.vapi.nat44_interface_add_del_feature(self.pg5.sw_if_index)
-        self.vapi.nat44_interface_add_del_feature(self.pg6.sw_if_index)
-        self.nat44_add_static_mapping(self.pg6.remote_ip4, static_nat_ip,
-                                      vrf_id=20)
-
-        # between NAT44 inside interfaces with same VRF (no translation)
-        pkts = self.create_stream_in(self.pg4, self.pg5)
-        self.pg4.add_stream(pkts)
-        self.pg_enable_capture(self.pg_interfaces)
-        self.pg_start()
-        capture = self.pg5.get_capture(len(pkts))
-        self.verify_capture_no_translation(capture, self.pg4, self.pg5)
-
-        # between NAT44 inside interfaces with different VRF (hairpinning)
-        p = (Ether(src=self.pg4.remote_mac, dst=self.pg4.local_mac) /
-             IP(src=self.pg4.remote_ip4, dst=static_nat_ip) /
-             TCP(sport=1234, dport=5678))
-        self.pg4.add_stream(p)
-        self.pg_enable_capture(self.pg_interfaces)
-        self.pg_start()
-        capture = self.pg6.get_capture(1)
-        p = capture[0]
-        try:
-            ip = p[IP]
-            tcp = p[TCP]
-            self.assertEqual(ip.src, self.nat_addr)
-            self.assertEqual(ip.dst, self.pg6.remote_ip4)
-            self.assertNotEqual(tcp.sport, 1234)
-            self.assertEqual(tcp.dport, 5678)
-        except:
-            self.logger.error(ppp("Unexpected or invalid packet:", p))
-            raise
-
-        # in2out 1st interface
-        pkts = self.create_stream_in(self.pg4, self.pg3)
-        self.pg4.add_stream(pkts)
-        self.pg_enable_capture(self.pg_interfaces)
-        self.pg_start()
-        capture = self.pg3.get_capture(len(pkts))
-        self.verify_capture_out(capture)
-
-        # out2in 1st interface
-        pkts = self.create_stream_out(self.pg3)
-        self.pg3.add_stream(pkts)
-        self.pg_enable_capture(self.pg_interfaces)
-        self.pg_start()
-        capture = self.pg4.get_capture(len(pkts))
-        self.verify_capture_in(capture, self.pg4)
-
-        # in2out 2nd interface
-        pkts = self.create_stream_in(self.pg5, self.pg3)
-        self.pg5.add_stream(pkts)
+        # in2out 2nd interface
+        pkts = self.create_stream_in(self.pg5, self.pg3)
+        self.pg5.add_stream(pkts)
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
         capture = self.pg3.get_capture(len(pkts))
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
         capture = self.pg3.get_capture(len(pkts))
@@ -2120,6 +1754,7 @@ class TestNAT44(MethodHolder):
                 self.assertTrue(session.protocol in
                                 [IP_PROTOS.tcp, IP_PROTOS.udp,
                                  IP_PROTOS.icmp])
                 self.assertTrue(session.protocol in
                                 [IP_PROTOS.tcp, IP_PROTOS.udp,
                                  IP_PROTOS.icmp])
+                self.assertFalse(session.ext_host_valid)
 
         # pg4 session dump
         sessions = self.vapi.nat44_user_session_dump(self.pg4.remote_ip4n, 10)
 
         # pg4 session dump
         sessions = self.vapi.nat44_user_session_dump(self.pg4.remote_ip4n, 10)
@@ -2179,7 +1814,7 @@ class TestNAT44(MethodHolder):
             self.assertEqual(ip.dst, server.ip4)
             self.assertNotEqual(tcp.sport, host_in_port)
             self.assertEqual(tcp.dport, server_in_port)
             self.assertEqual(ip.dst, server.ip4)
             self.assertNotEqual(tcp.sport, host_in_port)
             self.assertEqual(tcp.dport, server_in_port)
-            self.check_tcp_checksum(p)
+            self.assert_packet_checksums_valid(p)
             host_out_port = tcp.sport
         except:
             self.logger.error(ppp("Unexpected or invalid packet:", p))
             host_out_port = tcp.sport
         except:
             self.logger.error(ppp("Unexpected or invalid packet:", p))
@@ -2201,7 +1836,7 @@ class TestNAT44(MethodHolder):
             self.assertEqual(ip.dst, host.ip4)
             self.assertEqual(tcp.sport, server_out_port)
             self.assertEqual(tcp.dport, host_in_port)
             self.assertEqual(ip.dst, host.ip4)
             self.assertEqual(tcp.sport, server_out_port)
             self.assertEqual(tcp.dport, host_in_port)
-            self.check_tcp_checksum(p)
+            self.assert_packet_checksums_valid(p)
         except:
             self.logger.error(ppp("Unexpected or invalid packet:", p))
             raise
         except:
             self.logger.error(ppp("Unexpected or invalid packet:", p))
             raise
@@ -2252,7 +1887,7 @@ class TestNAT44(MethodHolder):
                     self.assertNotEqual(packet[TCP].sport, self.tcp_port_in)
                     self.assertEqual(packet[TCP].dport, server_tcp_port)
                     self.tcp_port_out = packet[TCP].sport
                     self.assertNotEqual(packet[TCP].sport, self.tcp_port_in)
                     self.assertEqual(packet[TCP].dport, server_tcp_port)
                     self.tcp_port_out = packet[TCP].sport
-                    self.check_tcp_checksum(packet)
+                    self.assert_packet_checksums_valid(packet)
                 elif packet.haslayer(UDP):
                     self.assertNotEqual(packet[UDP].sport, self.udp_port_in)
                     self.assertEqual(packet[UDP].dport, server_udp_port)
                 elif packet.haslayer(UDP):
                     self.assertNotEqual(packet[UDP].sport, self.udp_port_in)
                     self.assertEqual(packet[UDP].dport, server_udp_port)
@@ -2289,7 +1924,7 @@ class TestNAT44(MethodHolder):
                 if packet.haslayer(TCP):
                     self.assertEqual(packet[TCP].dport, self.tcp_port_in)
                     self.assertEqual(packet[TCP].sport, server_tcp_port)
                 if packet.haslayer(TCP):
                     self.assertEqual(packet[TCP].dport, self.tcp_port_in)
                     self.assertEqual(packet[TCP].sport, server_tcp_port)
-                    self.check_tcp_checksum(packet)
+                    self.assert_packet_checksums_valid(packet)
                 elif packet.haslayer(UDP):
                     self.assertEqual(packet[UDP].dport, self.udp_port_in)
                     self.assertEqual(packet[UDP].sport, server_udp_port)
                 elif packet.haslayer(UDP):
                     self.assertEqual(packet[UDP].dport, self.udp_port_in)
                     self.assertEqual(packet[UDP].sport, server_udp_port)
@@ -2325,7 +1960,7 @@ class TestNAT44(MethodHolder):
                     self.assertEqual(packet[TCP].sport, self.tcp_port_in)
                     self.assertEqual(packet[TCP].dport, server_tcp_port)
                     self.tcp_port_out = packet[TCP].sport
                     self.assertEqual(packet[TCP].sport, self.tcp_port_in)
                     self.assertEqual(packet[TCP].dport, server_tcp_port)
                     self.tcp_port_out = packet[TCP].sport
-                    self.check_tcp_checksum(packet)
+                    self.assert_packet_checksums_valid(packet)
                 elif packet.haslayer(UDP):
                     self.assertEqual(packet[UDP].sport, self.udp_port_in)
                     self.assertEqual(packet[UDP].dport, server_udp_port)
                 elif packet.haslayer(UDP):
                     self.assertEqual(packet[UDP].sport, self.udp_port_in)
                     self.assertEqual(packet[UDP].dport, server_udp_port)
@@ -2362,7 +1997,7 @@ class TestNAT44(MethodHolder):
                 if packet.haslayer(TCP):
                     self.assertEqual(packet[TCP].dport, self.tcp_port_in)
                     self.assertEqual(packet[TCP].sport, server_tcp_port)
                 if packet.haslayer(TCP):
                     self.assertEqual(packet[TCP].dport, self.tcp_port_in)
                     self.assertEqual(packet[TCP].sport, server_tcp_port)
-                    self.check_tcp_checksum(packet)
+                    self.assert_packet_checksums_valid(packet)
                 elif packet.haslayer(UDP):
                     self.assertEqual(packet[UDP].dport, self.udp_port_in)
                     self.assertEqual(packet[UDP].sport, server_udp_port)
                 elif packet.haslayer(UDP):
                     self.assertEqual(packet[UDP].dport, self.udp_port_in)
                     self.assertEqual(packet[UDP].sport, server_udp_port)
@@ -2398,6 +2033,31 @@ class TestNAT44(MethodHolder):
         # verify number of translated packet
         self.pg1.get_capture(pkts_num)
 
         # verify number of translated packet
         self.pg1.get_capture(pkts_num)
 
+        users = self.vapi.nat44_user_dump()
+        for user in users:
+            if user.ip_address == self.pg0.remote_ip4n:
+                self.assertEqual(user.nsessions,
+                                 nat44_config.max_translations_per_user)
+                self.assertEqual(user.nstaticsessions, 0)
+
+        tcp_port = 22
+        self.nat44_add_static_mapping(self.pg0.remote_ip4, self.nat_addr,
+                                      tcp_port, tcp_port,
+                                      proto=IP_PROTOS.tcp)
+        p = (Ether(dst=self.pg0.local_mac, src=self.pg0.remote_mac) /
+             IP(src=self.pg0.remote_ip4, dst=self.pg1.remote_ip4) /
+             TCP(sport=tcp_port))
+        self.pg0.add_stream(p)
+        self.pg_enable_capture(self.pg_interfaces)
+        self.pg_start()
+        self.pg1.get_capture(1)
+        users = self.vapi.nat44_user_dump()
+        for user in users:
+            if user.ip_address == self.pg0.remote_ip4n:
+                self.assertEqual(user.nsessions,
+                                 nat44_config.max_translations_per_user - 1)
+                self.assertEqual(user.nstaticsessions, 1)
+
     def test_interface_addr(self):
         """ Acquire NAT44 addresses from interface """
         self.vapi.nat44_add_interface_addr(self.pg7.sw_if_index)
     def test_interface_addr(self):
         """ Acquire NAT44 addresses from interface """
         self.vapi.nat44_add_interface_addr(self.pg7.sw_if_index)
@@ -2437,15 +2097,44 @@ class TestNAT44(MethodHolder):
         # configure interface address and check static mappings
         self.pg7.config_ip4()
         static_mappings = self.vapi.nat44_static_mapping_dump()
         # configure interface address and check static mappings
         self.pg7.config_ip4()
         static_mappings = self.vapi.nat44_static_mapping_dump()
-        self.assertEqual(1, len(static_mappings))
-        self.assertEqual(static_mappings[0].external_ip_address[0:4],
-                         self.pg7.local_ip4n)
-        self.assertEqual(0xFFFFFFFF, static_mappings[0].external_sw_if_index)
-        self.assertEqual((static_mappings[0].tag).split('\0', 1)[0], tag)
+        self.assertEqual(2, len(static_mappings))
+        resolved = False
+        for sm in static_mappings:
+            if sm.external_sw_if_index == 0xFFFFFFFF:
+                self.assertEqual(sm.external_ip_address[0:4],
+                                 self.pg7.local_ip4n)
+                self.assertEqual((sm.tag).split('\0', 1)[0], tag)
+                resolved = True
+        self.assertTrue(resolved)
 
         # remove interface address and check static mappings
         self.pg7.unconfig_ip4()
         static_mappings = self.vapi.nat44_static_mapping_dump()
 
         # remove interface address and check static mappings
         self.pg7.unconfig_ip4()
         static_mappings = self.vapi.nat44_static_mapping_dump()
+        self.assertEqual(1, len(static_mappings))
+        self.assertEqual(self.pg7.sw_if_index,
+                         static_mappings[0].external_sw_if_index)
+        self.assertEqual((static_mappings[0].tag).split('\0', 1)[0], tag)
+
+        # configure interface address again and check static mappings
+        self.pg7.config_ip4()
+        static_mappings = self.vapi.nat44_static_mapping_dump()
+        self.assertEqual(2, len(static_mappings))
+        resolved = False
+        for sm in static_mappings:
+            if sm.external_sw_if_index == 0xFFFFFFFF:
+                self.assertEqual(sm.external_ip_address[0:4],
+                                 self.pg7.local_ip4n)
+                self.assertEqual((sm.tag).split('\0', 1)[0], tag)
+                resolved = True
+        self.assertTrue(resolved)
+
+        # remove static mapping
+        self.nat44_add_static_mapping(
+            '1.2.3.4',
+            external_sw_if_index=self.pg7.sw_if_index,
+            tag=tag,
+            is_add=0)
+        static_mappings = self.vapi.nat44_static_mapping_dump()
         self.assertEqual(0, len(static_mappings))
 
     def test_interface_addr_identity_nat(self):
         self.assertEqual(0, len(static_mappings))
 
     def test_interface_addr_identity_nat(self):
@@ -2468,17 +2157,23 @@ class TestNAT44(MethodHolder):
         # configure interface address and check identity mappings
         self.pg7.config_ip4()
         identity_mappings = self.vapi.nat44_identity_mapping_dump()
         # configure interface address and check identity mappings
         self.pg7.config_ip4()
         identity_mappings = self.vapi.nat44_identity_mapping_dump()
-        self.assertEqual(1, len(identity_mappings))
-        self.assertEqual(identity_mappings[0].ip_address,
-                         self.pg7.local_ip4n)
-        self.assertEqual(0xFFFFFFFF, identity_mappings[0].sw_if_index)
-        self.assertEqual(port, identity_mappings[0].port)
-        self.assertEqual(IP_PROTOS.tcp, identity_mappings[0].protocol)
+        resolved = False
+        self.assertEqual(2, len(identity_mappings))
+        for sm in identity_mappings:
+            if sm.sw_if_index == 0xFFFFFFFF:
+                self.assertEqual(identity_mappings[0].ip_address,
+                                 self.pg7.local_ip4n)
+                self.assertEqual(port, identity_mappings[0].port)
+                self.assertEqual(IP_PROTOS.tcp, identity_mappings[0].protocol)
+                resolved = True
+        self.assertTrue(resolved)
 
         # remove interface address and check identity mappings
         self.pg7.unconfig_ip4()
         identity_mappings = self.vapi.nat44_identity_mapping_dump()
 
         # remove interface address and check identity mappings
         self.pg7.unconfig_ip4()
         identity_mappings = self.vapi.nat44_identity_mapping_dump()
-        self.assertEqual(0, len(identity_mappings))
+        self.assertEqual(1, len(identity_mappings))
+        self.assertEqual(self.pg7.sw_if_index,
+                         identity_mappings[0].sw_if_index)
 
     def test_ipfix_nat44_sess(self):
         """ IPFIX logging NAT44 session created/delted """
 
     def test_ipfix_nat44_sess(self):
         """ IPFIX logging NAT44 session created/delted """
@@ -2543,7 +2238,8 @@ class TestNAT44(MethodHolder):
         self.pg0.add_stream(p)
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
         self.pg0.add_stream(p)
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
-        capture = self.pg1.get_capture(0)
+        self.pg1.assert_nothing_captured()
+        sleep(1)
         self.vapi.cli("ipfix flush")  # FIXME this should be an API call
         capture = self.pg3.get_capture(9)
         ipfix = IPFIXDecoder()
         self.vapi.cli("ipfix flush")  # FIXME this should be an API call
         capture = self.pg3.get_capture(9)
         ipfix = IPFIXDecoder()
@@ -2600,7 +2296,8 @@ class TestNAT44(MethodHolder):
         self.pg0.add_stream(p)
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
         self.pg0.add_stream(p)
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
-        self.pg1.get_capture(0)
+        self.pg1.assert_nothing_captured()
+        sleep(1)
         self.vapi.cli("ipfix flush")  # FIXME this should be an API call
         capture = self.pg3.get_capture(9)
         ipfix = IPFIXDecoder()
         self.vapi.cli("ipfix flush")  # FIXME this should be an API call
         capture = self.pg3.get_capture(9)
         ipfix = IPFIXDecoder()
@@ -2659,7 +2356,7 @@ class TestNAT44(MethodHolder):
         self.pg2.add_stream(p)
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
         self.pg2.add_stream(p)
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
-        capture = self.pg1.get_capture(0)
+        self.pg1.assert_nothing_captured()
 
         # remove addresses and verify
         self.nat44_add_address(self.nat_addr, is_add=0)
 
         # remove addresses and verify
         self.nat44_add_address(self.nat_addr, is_add=0)
@@ -2672,7 +2369,7 @@ class TestNAT44(MethodHolder):
         self.pg1.add_stream(p)
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
         self.pg1.add_stream(p)
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
-        capture = self.pg1.get_capture(0)
+        self.pg1.assert_nothing_captured()
 
         p = (Ether(src=self.pg1.remote_mac, dst='ff:ff:ff:ff:ff:ff') /
              ARP(op=ARP.who_has, pdst=static_addr,
 
         p = (Ether(src=self.pg1.remote_mac, dst='ff:ff:ff:ff:ff:ff') /
              ARP(op=ARP.who_has, pdst=static_addr,
@@ -2680,7 +2377,7 @@ class TestNAT44(MethodHolder):
         self.pg1.add_stream(p)
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
         self.pg1.add_stream(p)
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
-        capture = self.pg1.get_capture(0)
+        self.pg1.assert_nothing_captured()
 
     def test_vrf_mode(self):
         """ NAT44 tenant VRF aware address pool mode """
 
     def test_vrf_mode(self):
         """ NAT44 tenant VRF aware address pool mode """
@@ -2698,6 +2395,8 @@ class TestNAT44(MethodHolder):
         self.pg1.set_table_ip4(vrf_id2)
         self.pg0.config_ip4()
         self.pg1.config_ip4()
         self.pg1.set_table_ip4(vrf_id2)
         self.pg0.config_ip4()
         self.pg1.config_ip4()
+        self.pg0.resolve_arp()
+        self.pg1.resolve_arp()
 
         self.nat44_add_address(nat_ip1, vrf_id=vrf_id1)
         self.nat44_add_address(nat_ip2, vrf_id=vrf_id2)
 
         self.nat44_add_address(nat_ip1, vrf_id=vrf_id1)
         self.nat44_add_address(nat_ip2, vrf_id=vrf_id2)
@@ -2706,28 +2405,34 @@ class TestNAT44(MethodHolder):
         self.vapi.nat44_interface_add_del_feature(self.pg2.sw_if_index,
                                                   is_inside=0)
 
         self.vapi.nat44_interface_add_del_feature(self.pg2.sw_if_index,
                                                   is_inside=0)
 
-        # first VRF
-        pkts = self.create_stream_in(self.pg0, self.pg2)
-        self.pg0.add_stream(pkts)
-        self.pg_enable_capture(self.pg_interfaces)
-        self.pg_start()
-        capture = self.pg2.get_capture(len(pkts))
-        self.verify_capture_out(capture, nat_ip1)
+        try:
+            # first VRF
+            pkts = self.create_stream_in(self.pg0, self.pg2)
+            self.pg0.add_stream(pkts)
+            self.pg_enable_capture(self.pg_interfaces)
+            self.pg_start()
+            capture = self.pg2.get_capture(len(pkts))
+            self.verify_capture_out(capture, nat_ip1)
 
 
-        # second VRF
-        pkts = self.create_stream_in(self.pg1, self.pg2)
-        self.pg1.add_stream(pkts)
-        self.pg_enable_capture(self.pg_interfaces)
-        self.pg_start()
-        capture = self.pg2.get_capture(len(pkts))
-        self.verify_capture_out(capture, nat_ip2)
+            # second VRF
+            pkts = self.create_stream_in(self.pg1, self.pg2)
+            self.pg1.add_stream(pkts)
+            self.pg_enable_capture(self.pg_interfaces)
+            self.pg_start()
+            capture = self.pg2.get_capture(len(pkts))
+            self.verify_capture_out(capture, nat_ip2)
 
 
-        self.pg0.unconfig_ip4()
-        self.pg1.unconfig_ip4()
-        self.pg0.set_table_ip4(0)
-        self.pg1.set_table_ip4(0)
-        self.vapi.ip_table_add_del(vrf_id1, is_add=0)
-        self.vapi.ip_table_add_del(vrf_id2, is_add=0)
+        finally:
+            self.pg0.unconfig_ip4()
+            self.pg1.unconfig_ip4()
+            self.pg0.set_table_ip4(0)
+            self.pg1.set_table_ip4(0)
+            self.pg0.config_ip4()
+            self.pg1.config_ip4()
+            self.pg0.resolve_arp()
+            self.pg1.resolve_arp()
+            self.vapi.ip_table_add_del(vrf_id1, is_add=0)
+            self.vapi.ip_table_add_del(vrf_id2, is_add=0)
 
     def test_vrf_feature_independent(self):
         """ NAT44 tenant VRF independent address pool mode """
 
     def test_vrf_feature_independent(self):
         """ NAT44 tenant VRF independent address pool mode """
@@ -2897,107 +2602,1143 @@ class TestNAT44(MethodHolder):
         capture = self.pg8.get_capture(len(pkts))
         self.verify_capture_out(capture)
 
         capture = self.pg8.get_capture(len(pkts))
         self.verify_capture_out(capture)
 
-    def test_static_unknown_proto(self):
-        """ 1:1 NAT translate packet with unknown protocol """
-        nat_ip = "10.0.0.10"
-        self.nat44_add_static_mapping(self.pg0.remote_ip4, nat_ip)
+    def test_static_unknown_proto(self):
+        """ 1:1 NAT translate packet with unknown protocol """
+        nat_ip = "10.0.0.10"
+        self.nat44_add_static_mapping(self.pg0.remote_ip4, nat_ip)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
+
+        # in2out
+        p = (Ether(dst=self.pg0.local_mac, src=self.pg0.remote_mac) /
+             IP(src=self.pg0.remote_ip4, dst=self.pg1.remote_ip4) /
+             GRE() /
+             IP(src=self.pg2.remote_ip4, dst=self.pg3.remote_ip4) /
+             TCP(sport=1234, dport=1234))
+        self.pg0.add_stream(p)
+        self.pg_enable_capture(self.pg_interfaces)
+        self.pg_start()
+        p = self.pg1.get_capture(1)
+        packet = p[0]
+        try:
+            self.assertEqual(packet[IP].src, nat_ip)
+            self.assertEqual(packet[IP].dst, self.pg1.remote_ip4)
+            self.assertTrue(packet.haslayer(GRE))
+            self.assert_packet_checksums_valid(packet)
+        except:
+            self.logger.error(ppp("Unexpected or invalid packet:", packet))
+            raise
+
+        # out2in
+        p = (Ether(dst=self.pg1.local_mac, src=self.pg1.remote_mac) /
+             IP(src=self.pg1.remote_ip4, dst=nat_ip) /
+             GRE() /
+             IP(src=self.pg3.remote_ip4, dst=self.pg2.remote_ip4) /
+             TCP(sport=1234, dport=1234))
+        self.pg1.add_stream(p)
+        self.pg_enable_capture(self.pg_interfaces)
+        self.pg_start()
+        p = self.pg0.get_capture(1)
+        packet = p[0]
+        try:
+            self.assertEqual(packet[IP].src, self.pg1.remote_ip4)
+            self.assertEqual(packet[IP].dst, self.pg0.remote_ip4)
+            self.assertTrue(packet.haslayer(GRE))
+            self.assert_packet_checksums_valid(packet)
+        except:
+            self.logger.error(ppp("Unexpected or invalid packet:", packet))
+            raise
+
+    def test_hairpinning_static_unknown_proto(self):
+        """ 1:1 NAT translate packet with unknown protocol - hairpinning """
+
+        host = self.pg0.remote_hosts[0]
+        server = self.pg0.remote_hosts[1]
+
+        host_nat_ip = "10.0.0.10"
+        server_nat_ip = "10.0.0.11"
+
+        self.nat44_add_static_mapping(host.ip4, host_nat_ip)
+        self.nat44_add_static_mapping(server.ip4, server_nat_ip)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
+
+        # host to server
+        p = (Ether(dst=self.pg0.local_mac, src=host.mac) /
+             IP(src=host.ip4, dst=server_nat_ip) /
+             GRE() /
+             IP(src=self.pg2.remote_ip4, dst=self.pg3.remote_ip4) /
+             TCP(sport=1234, dport=1234))
+        self.pg0.add_stream(p)
+        self.pg_enable_capture(self.pg_interfaces)
+        self.pg_start()
+        p = self.pg0.get_capture(1)
+        packet = p[0]
+        try:
+            self.assertEqual(packet[IP].src, host_nat_ip)
+            self.assertEqual(packet[IP].dst, server.ip4)
+            self.assertTrue(packet.haslayer(GRE))
+            self.assert_packet_checksums_valid(packet)
+        except:
+            self.logger.error(ppp("Unexpected or invalid packet:", packet))
+            raise
+
+        # server to host
+        p = (Ether(dst=self.pg0.local_mac, src=server.mac) /
+             IP(src=server.ip4, dst=host_nat_ip) /
+             GRE() /
+             IP(src=self.pg3.remote_ip4, dst=self.pg2.remote_ip4) /
+             TCP(sport=1234, dport=1234))
+        self.pg0.add_stream(p)
+        self.pg_enable_capture(self.pg_interfaces)
+        self.pg_start()
+        p = self.pg0.get_capture(1)
+        packet = p[0]
+        try:
+            self.assertEqual(packet[IP].src, server_nat_ip)
+            self.assertEqual(packet[IP].dst, host.ip4)
+            self.assertTrue(packet.haslayer(GRE))
+            self.assert_packet_checksums_valid(packet)
+        except:
+            self.logger.error(ppp("Unexpected or invalid packet:", packet))
+            raise
+
+    def test_output_feature(self):
+        """ NAT44 interface output feature (in2out postrouting) """
+        self.nat44_add_address(self.nat_addr)
+        self.vapi.nat44_interface_add_del_output_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_output_feature(self.pg1.sw_if_index)
+        self.vapi.nat44_interface_add_del_output_feature(self.pg3.sw_if_index,
+                                                         is_inside=0)
+
+        # in2out
+        pkts = self.create_stream_in(self.pg0, self.pg3)
+        self.pg0.add_stream(pkts)
+        self.pg_enable_capture(self.pg_interfaces)
+        self.pg_start()
+        capture = self.pg3.get_capture(len(pkts))
+        self.verify_capture_out(capture)
+
+        # out2in
+        pkts = self.create_stream_out(self.pg3)
+        self.pg3.add_stream(pkts)
+        self.pg_enable_capture(self.pg_interfaces)
+        self.pg_start()
+        capture = self.pg0.get_capture(len(pkts))
+        self.verify_capture_in(capture, self.pg0)
+
+        # from non-NAT interface to NAT inside interface
+        pkts = self.create_stream_in(self.pg2, self.pg0)
+        self.pg2.add_stream(pkts)
+        self.pg_enable_capture(self.pg_interfaces)
+        self.pg_start()
+        capture = self.pg0.get_capture(len(pkts))
+        self.verify_capture_no_translation(capture, self.pg2, self.pg0)
+
+    def test_output_feature_vrf_aware(self):
+        """ NAT44 interface output feature VRF aware (in2out postrouting) """
+        nat_ip_vrf10 = "10.0.0.10"
+        nat_ip_vrf20 = "10.0.0.20"
+
+        self.vapi.ip_add_del_route(dst_address=self.pg3.remote_ip4n,
+                                   dst_address_length=32,
+                                   next_hop_address=self.pg3.remote_ip4n,
+                                   next_hop_sw_if_index=self.pg3.sw_if_index,
+                                   table_id=10)
+        self.vapi.ip_add_del_route(dst_address=self.pg3.remote_ip4n,
+                                   dst_address_length=32,
+                                   next_hop_address=self.pg3.remote_ip4n,
+                                   next_hop_sw_if_index=self.pg3.sw_if_index,
+                                   table_id=20)
+
+        self.nat44_add_address(nat_ip_vrf10, vrf_id=10)
+        self.nat44_add_address(nat_ip_vrf20, vrf_id=20)
+        self.vapi.nat44_interface_add_del_output_feature(self.pg4.sw_if_index)
+        self.vapi.nat44_interface_add_del_output_feature(self.pg6.sw_if_index)
+        self.vapi.nat44_interface_add_del_output_feature(self.pg3.sw_if_index,
+                                                         is_inside=0)
+
+        # in2out VRF 10
+        pkts = self.create_stream_in(self.pg4, self.pg3)
+        self.pg4.add_stream(pkts)
+        self.pg_enable_capture(self.pg_interfaces)
+        self.pg_start()
+        capture = self.pg3.get_capture(len(pkts))
+        self.verify_capture_out(capture, nat_ip=nat_ip_vrf10)
+
+        # out2in VRF 10
+        pkts = self.create_stream_out(self.pg3, dst_ip=nat_ip_vrf10)
+        self.pg3.add_stream(pkts)
+        self.pg_enable_capture(self.pg_interfaces)
+        self.pg_start()
+        capture = self.pg4.get_capture(len(pkts))
+        self.verify_capture_in(capture, self.pg4)
+
+        # in2out VRF 20
+        pkts = self.create_stream_in(self.pg6, self.pg3)
+        self.pg6.add_stream(pkts)
+        self.pg_enable_capture(self.pg_interfaces)
+        self.pg_start()
+        capture = self.pg3.get_capture(len(pkts))
+        self.verify_capture_out(capture, nat_ip=nat_ip_vrf20)
+
+        # out2in VRF 20
+        pkts = self.create_stream_out(self.pg3, dst_ip=nat_ip_vrf20)
+        self.pg3.add_stream(pkts)
+        self.pg_enable_capture(self.pg_interfaces)
+        self.pg_start()
+        capture = self.pg6.get_capture(len(pkts))
+        self.verify_capture_in(capture, self.pg6)
+
+    def test_output_feature_hairpinning(self):
+        """ NAT44 interface output feature hairpinning (in2out postrouting) """
+        host = self.pg0.remote_hosts[0]
+        server = self.pg0.remote_hosts[1]
+        host_in_port = 1234
+        host_out_port = 0
+        server_in_port = 5678
+        server_out_port = 8765
+
+        self.nat44_add_address(self.nat_addr)
+        self.vapi.nat44_interface_add_del_output_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_output_feature(self.pg1.sw_if_index,
+                                                         is_inside=0)
+
+        # add static mapping for server
+        self.nat44_add_static_mapping(server.ip4, self.nat_addr,
+                                      server_in_port, server_out_port,
+                                      proto=IP_PROTOS.tcp)
+
+        # send packet from host to server
+        p = (Ether(src=host.mac, dst=self.pg0.local_mac) /
+             IP(src=host.ip4, dst=self.nat_addr) /
+             TCP(sport=host_in_port, dport=server_out_port))
+        self.pg0.add_stream(p)
+        self.pg_enable_capture(self.pg_interfaces)
+        self.pg_start()
+        capture = self.pg0.get_capture(1)
+        p = capture[0]
+        try:
+            ip = p[IP]
+            tcp = p[TCP]
+            self.assertEqual(ip.src, self.nat_addr)
+            self.assertEqual(ip.dst, server.ip4)
+            self.assertNotEqual(tcp.sport, host_in_port)
+            self.assertEqual(tcp.dport, server_in_port)
+            self.assert_packet_checksums_valid(p)
+            host_out_port = tcp.sport
+        except:
+            self.logger.error(ppp("Unexpected or invalid packet:", p))
+            raise
+
+        # send reply from server to host
+        p = (Ether(src=server.mac, dst=self.pg0.local_mac) /
+             IP(src=server.ip4, dst=self.nat_addr) /
+             TCP(sport=server_in_port, dport=host_out_port))
+        self.pg0.add_stream(p)
+        self.pg_enable_capture(self.pg_interfaces)
+        self.pg_start()
+        capture = self.pg0.get_capture(1)
+        p = capture[0]
+        try:
+            ip = p[IP]
+            tcp = p[TCP]
+            self.assertEqual(ip.src, self.nat_addr)
+            self.assertEqual(ip.dst, host.ip4)
+            self.assertEqual(tcp.sport, server_out_port)
+            self.assertEqual(tcp.dport, host_in_port)
+            self.assert_packet_checksums_valid(p)
+        except:
+            self.logger.error(ppp("Unexpected or invalid packet:", p))
+            raise
+
+    def test_one_armed_nat44(self):
+        """ One armed NAT44 """
+        remote_host = self.pg9.remote_hosts[0]
+        local_host = self.pg9.remote_hosts[1]
+        external_port = 0
+
+        self.nat44_add_address(self.nat_addr)
+        self.vapi.nat44_interface_add_del_feature(self.pg9.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg9.sw_if_index,
+                                                  is_inside=0)
+
+        # in2out
+        p = (Ether(src=self.pg9.remote_mac, dst=self.pg9.local_mac) /
+             IP(src=local_host.ip4, dst=remote_host.ip4) /
+             TCP(sport=12345, dport=80))
+        self.pg9.add_stream(p)
+        self.pg_enable_capture(self.pg_interfaces)
+        self.pg_start()
+        capture = self.pg9.get_capture(1)
+        p = capture[0]
+        try:
+            ip = p[IP]
+            tcp = p[TCP]
+            self.assertEqual(ip.src, self.nat_addr)
+            self.assertEqual(ip.dst, remote_host.ip4)
+            self.assertNotEqual(tcp.sport, 12345)
+            external_port = tcp.sport
+            self.assertEqual(tcp.dport, 80)
+            self.assert_packet_checksums_valid(p)
+        except:
+            self.logger.error(ppp("Unexpected or invalid packet:", p))
+            raise
+
+        # out2in
+        p = (Ether(src=self.pg9.remote_mac, dst=self.pg9.local_mac) /
+             IP(src=remote_host.ip4, dst=self.nat_addr) /
+             TCP(sport=80, dport=external_port))
+        self.pg9.add_stream(p)
+        self.pg_enable_capture(self.pg_interfaces)
+        self.pg_start()
+        capture = self.pg9.get_capture(1)
+        p = capture[0]
+        try:
+            ip = p[IP]
+            tcp = p[TCP]
+            self.assertEqual(ip.src, remote_host.ip4)
+            self.assertEqual(ip.dst, local_host.ip4)
+            self.assertEqual(tcp.sport, 80)
+            self.assertEqual(tcp.dport, 12345)
+            self.assert_packet_checksums_valid(p)
+        except:
+            self.logger.error(ppp("Unexpected or invalid packet:", p))
+            raise
+
+    def test_del_session(self):
+        """ Delete NAT44 session """
+        self.nat44_add_address(self.nat_addr)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
+
+        pkts = self.create_stream_in(self.pg0, self.pg1)
+        self.pg0.add_stream(pkts)
+        self.pg_enable_capture(self.pg_interfaces)
+        self.pg_start()
+        self.pg1.get_capture(len(pkts))
+
+        sessions = self.vapi.nat44_user_session_dump(self.pg0.remote_ip4n, 0)
+        nsessions = len(sessions)
+
+        self.vapi.nat44_del_session(sessions[0].inside_ip_address,
+                                    sessions[0].inside_port,
+                                    sessions[0].protocol)
+        self.vapi.nat44_del_session(sessions[1].outside_ip_address,
+                                    sessions[1].outside_port,
+                                    sessions[1].protocol,
+                                    is_in=0)
+
+        sessions = self.vapi.nat44_user_session_dump(self.pg0.remote_ip4n, 0)
+        self.assertEqual(nsessions - len(sessions), 2)
+
+        self.vapi.nat44_del_session(sessions[0].inside_ip_address,
+                                    sessions[0].inside_port,
+                                    sessions[0].protocol)
+
+        self.verify_no_nat44_user()
+
+    def test_set_get_reass(self):
+        """ NAT44 set/get virtual fragmentation reassembly """
+        reas_cfg1 = self.vapi.nat_get_reass()
+
+        self.vapi.nat_set_reass(timeout=reas_cfg1.ip4_timeout + 5,
+                                max_reass=reas_cfg1.ip4_max_reass * 2,
+                                max_frag=reas_cfg1.ip4_max_frag * 2)
+
+        reas_cfg2 = self.vapi.nat_get_reass()
+
+        self.assertEqual(reas_cfg1.ip4_timeout + 5, reas_cfg2.ip4_timeout)
+        self.assertEqual(reas_cfg1.ip4_max_reass * 2, reas_cfg2.ip4_max_reass)
+        self.assertEqual(reas_cfg1.ip4_max_frag * 2, reas_cfg2.ip4_max_frag)
+
+        self.vapi.nat_set_reass(drop_frag=1)
+        self.assertTrue(self.vapi.nat_get_reass().ip4_drop_frag)
+
+    def test_frag_in_order(self):
+        """ NAT44 translate fragments arriving in order """
+        self.nat44_add_address(self.nat_addr)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
+
+        data = "A" * 4 + "B" * 16 + "C" * 3
+        self.tcp_port_in = random.randint(1025, 65535)
+
+        reass = self.vapi.nat_reass_dump()
+        reass_n_start = len(reass)
+
+        # in2out
+        pkts = self.create_stream_frag(self.pg0,
+                                       self.pg1.remote_ip4,
+                                       self.tcp_port_in,
+                                       20,
+                                       data)
+        self.pg0.add_stream(pkts)
+        self.pg_enable_capture(self.pg_interfaces)
+        self.pg_start()
+        frags = self.pg1.get_capture(len(pkts))
+        p = self.reass_frags_and_verify(frags,
+                                        self.nat_addr,
+                                        self.pg1.remote_ip4)
+        self.assertEqual(p[TCP].dport, 20)
+        self.assertNotEqual(p[TCP].sport, self.tcp_port_in)
+        self.tcp_port_out = p[TCP].sport
+        self.assertEqual(data, p[Raw].load)
+
+        # out2in
+        pkts = self.create_stream_frag(self.pg1,
+                                       self.nat_addr,
+                                       20,
+                                       self.tcp_port_out,
+                                       data)
+        self.pg1.add_stream(pkts)
+        self.pg_enable_capture(self.pg_interfaces)
+        self.pg_start()
+        frags = self.pg0.get_capture(len(pkts))
+        p = self.reass_frags_and_verify(frags,
+                                        self.pg1.remote_ip4,
+                                        self.pg0.remote_ip4)
+        self.assertEqual(p[TCP].sport, 20)
+        self.assertEqual(p[TCP].dport, self.tcp_port_in)
+        self.assertEqual(data, p[Raw].load)
+
+        reass = self.vapi.nat_reass_dump()
+        reass_n_end = len(reass)
+
+        self.assertEqual(reass_n_end - reass_n_start, 2)
+
+    def test_reass_hairpinning(self):
+        """ NAT44 fragments hairpinning """
+        server = self.pg0.remote_hosts[1]
+        host_in_port = random.randint(1025, 65535)
+        server_in_port = random.randint(1025, 65535)
+        server_out_port = random.randint(1025, 65535)
+        data = "A" * 4 + "B" * 16 + "C" * 3
+
+        self.nat44_add_address(self.nat_addr)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
+        # add static mapping for server
+        self.nat44_add_static_mapping(server.ip4, self.nat_addr,
+                                      server_in_port, server_out_port,
+                                      proto=IP_PROTOS.tcp)
+
+        # send packet from host to server
+        pkts = self.create_stream_frag(self.pg0,
+                                       self.nat_addr,
+                                       host_in_port,
+                                       server_out_port,
+                                       data)
+        self.pg0.add_stream(pkts)
+        self.pg_enable_capture(self.pg_interfaces)
+        self.pg_start()
+        frags = self.pg0.get_capture(len(pkts))
+        p = self.reass_frags_and_verify(frags,
+                                        self.nat_addr,
+                                        server.ip4)
+        self.assertNotEqual(p[TCP].sport, host_in_port)
+        self.assertEqual(p[TCP].dport, server_in_port)
+        self.assertEqual(data, p[Raw].load)
+
+    def test_frag_out_of_order(self):
+        """ NAT44 translate fragments arriving out of order """
+        self.nat44_add_address(self.nat_addr)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
+
+        data = "A" * 4 + "B" * 16 + "C" * 3
+        random.randint(1025, 65535)
+
+        # in2out
+        pkts = self.create_stream_frag(self.pg0,
+                                       self.pg1.remote_ip4,
+                                       self.tcp_port_in,
+                                       20,
+                                       data)
+        pkts.reverse()
+        self.pg0.add_stream(pkts)
+        self.pg_enable_capture(self.pg_interfaces)
+        self.pg_start()
+        frags = self.pg1.get_capture(len(pkts))
+        p = self.reass_frags_and_verify(frags,
+                                        self.nat_addr,
+                                        self.pg1.remote_ip4)
+        self.assertEqual(p[TCP].dport, 20)
+        self.assertNotEqual(p[TCP].sport, self.tcp_port_in)
+        self.tcp_port_out = p[TCP].sport
+        self.assertEqual(data, p[Raw].load)
+
+        # out2in
+        pkts = self.create_stream_frag(self.pg1,
+                                       self.nat_addr,
+                                       20,
+                                       self.tcp_port_out,
+                                       data)
+        pkts.reverse()
+        self.pg1.add_stream(pkts)
+        self.pg_enable_capture(self.pg_interfaces)
+        self.pg_start()
+        frags = self.pg0.get_capture(len(pkts))
+        p = self.reass_frags_and_verify(frags,
+                                        self.pg1.remote_ip4,
+                                        self.pg0.remote_ip4)
+        self.assertEqual(p[TCP].sport, 20)
+        self.assertEqual(p[TCP].dport, self.tcp_port_in)
+        self.assertEqual(data, p[Raw].load)
+
+    def test_port_restricted(self):
+        """ Port restricted NAT44 (MAP-E CE) """
+        self.nat44_add_address(self.nat_addr)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
+        self.vapi.cli("nat addr-port-assignment-alg map-e psid 10 "
+                      "psid-offset 6 psid-len 6")
+
+        p = (Ether(src=self.pg0.remote_mac, dst=self.pg0.local_mac) /
+             IP(src=self.pg0.remote_ip4, dst=self.pg1.remote_ip4) /
+             TCP(sport=4567, dport=22))
+        self.pg0.add_stream(p)
+        self.pg_enable_capture(self.pg_interfaces)
+        self.pg_start()
+        capture = self.pg1.get_capture(1)
+        p = capture[0]
+        try:
+            ip = p[IP]
+            tcp = p[TCP]
+            self.assertEqual(ip.dst, self.pg1.remote_ip4)
+            self.assertEqual(ip.src, self.nat_addr)
+            self.assertEqual(tcp.dport, 22)
+            self.assertNotEqual(tcp.sport, 4567)
+            self.assertEqual((tcp.sport >> 6) & 63, 10)
+            self.assert_packet_checksums_valid(p)
+        except:
+            self.logger.error(ppp("Unexpected or invalid packet:", p))
+            raise
+
+    def test_ipfix_max_frags(self):
+        """ IPFIX logging maximum fragments pending reassembly exceeded """
+        self.nat44_add_address(self.nat_addr)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
+        self.vapi.nat_set_reass(max_frag=0)
+        self.vapi.set_ipfix_exporter(collector_address=self.pg3.remote_ip4n,
+                                     src_address=self.pg3.local_ip4n,
+                                     path_mtu=512,
+                                     template_interval=10)
+        self.vapi.nat_ipfix(domain_id=self.ipfix_domain_id,
+                            src_port=self.ipfix_src_port)
+
+        data = "A" * 4 + "B" * 16 + "C" * 3
+        self.tcp_port_in = random.randint(1025, 65535)
+        pkts = self.create_stream_frag(self.pg0,
+                                       self.pg1.remote_ip4,
+                                       self.tcp_port_in,
+                                       20,
+                                       data)
+        self.pg0.add_stream(pkts[-1])
+        self.pg_enable_capture(self.pg_interfaces)
+        self.pg_start()
+        self.pg1.assert_nothing_captured()
+        sleep(1)
+        self.vapi.cli("ipfix flush")  # FIXME this should be an API call
+        capture = self.pg3.get_capture(9)
+        ipfix = IPFIXDecoder()
+        # first load template
+        for p in capture:
+            self.assertTrue(p.haslayer(IPFIX))
+            self.assertEqual(p[IP].src, self.pg3.local_ip4)
+            self.assertEqual(p[IP].dst, self.pg3.remote_ip4)
+            self.assertEqual(p[UDP].sport, self.ipfix_src_port)
+            self.assertEqual(p[UDP].dport, 4739)
+            self.assertEqual(p[IPFIX].observationDomainID,
+                             self.ipfix_domain_id)
+            if p.haslayer(Template):
+                ipfix.add_template(p.getlayer(Template))
+        # verify events in data set
+        for p in capture:
+            if p.haslayer(Data):
+                data = ipfix.decode_data_set(p.getlayer(Set))
+                self.verify_ipfix_max_fragments_ip4(data, 0,
+                                                    self.pg0.remote_ip4n)
+
+    def test_multiple_outside_vrf(self):
+        """ Multiple outside VRF """
+        vrf_id1 = 1
+        vrf_id2 = 2
+
+        self.pg1.unconfig_ip4()
+        self.pg2.unconfig_ip4()
+        self.vapi.ip_table_add_del(vrf_id1, is_add=1)
+        self.vapi.ip_table_add_del(vrf_id2, is_add=1)
+        self.pg1.set_table_ip4(vrf_id1)
+        self.pg2.set_table_ip4(vrf_id2)
+        self.pg1.config_ip4()
+        self.pg2.config_ip4()
+        self.pg1.resolve_arp()
+        self.pg2.resolve_arp()
+
+        self.nat44_add_address(self.nat_addr)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
+        self.vapi.nat44_interface_add_del_feature(self.pg2.sw_if_index,
+                                                  is_inside=0)
+
+        try:
+            # first VRF
+            pkts = self.create_stream_in(self.pg0, self.pg1)
+            self.pg0.add_stream(pkts)
+            self.pg_enable_capture(self.pg_interfaces)
+            self.pg_start()
+            capture = self.pg1.get_capture(len(pkts))
+            self.verify_capture_out(capture, self.nat_addr)
+
+            pkts = self.create_stream_out(self.pg1, self.nat_addr)
+            self.pg1.add_stream(pkts)
+            self.pg_enable_capture(self.pg_interfaces)
+            self.pg_start()
+            capture = self.pg0.get_capture(len(pkts))
+            self.verify_capture_in(capture, self.pg0)
+
+            self.tcp_port_in = 60303
+            self.udp_port_in = 60304
+            self.icmp_id_in = 60305
+
+            # second VRF
+            pkts = self.create_stream_in(self.pg0, self.pg2)
+            self.pg0.add_stream(pkts)
+            self.pg_enable_capture(self.pg_interfaces)
+            self.pg_start()
+            capture = self.pg2.get_capture(len(pkts))
+            self.verify_capture_out(capture, self.nat_addr)
+
+            pkts = self.create_stream_out(self.pg2, self.nat_addr)
+            self.pg2.add_stream(pkts)
+            self.pg_enable_capture(self.pg_interfaces)
+            self.pg_start()
+            capture = self.pg0.get_capture(len(pkts))
+            self.verify_capture_in(capture, self.pg0)
+
+        finally:
+            self.pg1.unconfig_ip4()
+            self.pg2.unconfig_ip4()
+            self.pg1.set_table_ip4(0)
+            self.pg2.set_table_ip4(0)
+            self.pg1.config_ip4()
+            self.pg2.config_ip4()
+            self.pg1.resolve_arp()
+            self.pg2.resolve_arp()
+
+    @unittest.skipUnless(running_extended_tests(), "part of extended tests")
+    def test_session_timeout(self):
+        """ NAT44 session timeouts """
+        self.nat44_add_address(self.nat_addr)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
+        self.vapi.nat_set_timeouts(udp=5)
+
+        max_sessions = 1000
+        pkts = []
+        for i in range(0, max_sessions):
+            src = "10.10.%u.%u" % ((i & 0xFF00) >> 8, i & 0xFF)
+            p = (Ether(dst=self.pg0.local_mac, src=self.pg0.remote_mac) /
+                 IP(src=src, dst=self.pg1.remote_ip4) /
+                 UDP(sport=1025, dport=53))
+            pkts.append(p)
+        self.pg0.add_stream(pkts)
+        self.pg_enable_capture(self.pg_interfaces)
+        self.pg_start()
+        self.pg1.get_capture(max_sessions)
+
+        sleep(6)
+
+        pkts = []
+        for i in range(0, max_sessions):
+            src = "10.10.%u.%u" % ((i & 0xFF00) >> 8, i & 0xFF)
+            p = (Ether(dst=self.pg0.local_mac, src=self.pg0.remote_mac) /
+                 IP(src=src, dst=self.pg1.remote_ip4) /
+                 UDP(sport=1026, dport=53))
+            pkts.append(p)
+        self.pg0.add_stream(pkts)
+        self.pg_enable_capture(self.pg_interfaces)
+        self.pg_start()
+        self.pg1.get_capture(max_sessions)
+
+        nsessions = 0
+        users = self.vapi.nat44_user_dump()
+        for user in users:
+            nsessions = nsessions + user.nsessions
+        self.assertLess(nsessions, 2 * max_sessions)
+
+    def tearDown(self):
+        super(TestNAT44, self).tearDown()
+        if not self.vpp_dead:
+            self.logger.info(self.vapi.cli("show nat44 addresses"))
+            self.logger.info(self.vapi.cli("show nat44 interfaces"))
+            self.logger.info(self.vapi.cli("show nat44 static mappings"))
+            self.logger.info(self.vapi.cli("show nat44 interface address"))
+            self.logger.info(self.vapi.cli("show nat44 sessions detail"))
+            self.logger.info(self.vapi.cli("show nat virtual-reassembly"))
+            self.logger.info(self.vapi.cli("show nat44 hash tables detail"))
+            self.logger.info(self.vapi.cli("show nat timeouts"))
+            self.vapi.cli("nat addr-port-assignment-alg default")
+            self.clear_nat44()
+            self.vapi.cli("clear logging")
+
+
+class TestNAT44EndpointDependent(MethodHolder):
+    """ Endpoint-Dependent mapping and filtering test cases """
+
+    @classmethod
+    def setUpConstants(cls):
+        super(TestNAT44EndpointDependent, cls).setUpConstants()
+        cls.vpp_cmdline.extend(["nat", "{", "endpoint-dependent", "}"])
+
+    @classmethod
+    def setUpClass(cls):
+        super(TestNAT44EndpointDependent, cls).setUpClass()
+        cls.vapi.cli("set log class nat level debug")
+        try:
+            cls.tcp_port_in = 6303
+            cls.tcp_port_out = 6303
+            cls.udp_port_in = 6304
+            cls.udp_port_out = 6304
+            cls.icmp_id_in = 6305
+            cls.icmp_id_out = 6305
+            cls.nat_addr = '10.0.0.3'
+            cls.nat_addr_n = socket.inet_pton(socket.AF_INET, cls.nat_addr)
+            cls.ipfix_src_port = 4739
+            cls.ipfix_domain_id = 1
+            cls.tcp_external_port = 80
+
+            cls.create_pg_interfaces(range(7))
+            cls.interfaces = list(cls.pg_interfaces[0:3])
+
+            for i in cls.interfaces:
+                i.admin_up()
+                i.config_ip4()
+                i.resolve_arp()
+
+            cls.pg0.generate_remote_hosts(3)
+            cls.pg0.configure_ipv4_neighbors()
+
+            cls.pg3.admin_up()
+
+            cls.pg4.generate_remote_hosts(2)
+            cls.pg4.config_ip4()
+            ip_addr_n = socket.inet_pton(socket.AF_INET, "10.0.0.1")
+            cls.vapi.sw_interface_add_del_address(cls.pg4.sw_if_index,
+                                                  ip_addr_n,
+                                                  24)
+            cls.pg4.admin_up()
+            cls.pg4.resolve_arp()
+            cls.pg4._remote_hosts[1]._ip4 = cls.pg4._remote_hosts[0]._ip4
+            cls.pg4.resolve_arp()
+
+            zero_ip4n = socket.inet_pton(socket.AF_INET, "0.0.0.0")
+            cls.vapi.ip_table_add_del(1, is_add=1)
+
+            cls.pg5._local_ip4 = "10.1.1.1"
+            cls.pg5._local_ip4n = socket.inet_pton(socket.AF_INET,
+                                                   cls.pg5.local_ip4)
+            cls.pg5._remote_hosts[0]._ip4 = "10.1.1.2"
+            cls.pg5._remote_hosts[0]._ip4n = socket.inet_pton(
+                socket.AF_INET, cls.pg5.remote_ip4)
+            cls.pg5.set_table_ip4(1)
+            cls.pg5.config_ip4()
+            cls.pg5.admin_up()
+            cls.vapi.ip_add_del_route(dst_address=cls.pg5.remote_ip4n,
+                                      dst_address_length=32,
+                                      table_id=1,
+                                      next_hop_sw_if_index=cls.pg5.sw_if_index,
+                                      next_hop_address=zero_ip4n)
+
+            cls.pg6._local_ip4 = "10.1.2.1"
+            cls.pg6._local_ip4n = socket.inet_pton(socket.AF_INET,
+                                                   cls.pg6.local_ip4)
+            cls.pg6._remote_hosts[0]._ip4 = "10.1.2.2"
+            cls.pg6._remote_hosts[0]._ip4n = socket.inet_pton(
+                socket.AF_INET, cls.pg6.remote_ip4)
+            cls.pg6.set_table_ip4(1)
+            cls.pg6.config_ip4()
+            cls.pg6.admin_up()
+            cls.vapi.ip_add_del_route(dst_address=cls.pg6.remote_ip4n,
+                                      dst_address_length=32,
+                                      table_id=1,
+                                      next_hop_sw_if_index=cls.pg6.sw_if_index,
+                                      next_hop_address=zero_ip4n)
+
+            cls.vapi.ip_add_del_route(dst_address=cls.pg6.remote_ip4n,
+                                      dst_address_length=16,
+                                      next_hop_address=zero_ip4n,
+                                      table_id=0,
+                                      next_hop_table_id=1)
+            cls.vapi.ip_add_del_route(dst_address=zero_ip4n,
+                                      dst_address_length=0,
+                                      next_hop_address=zero_ip4n,
+                                      table_id=1,
+                                      next_hop_table_id=0)
+            cls.vapi.ip_add_del_route(dst_address=zero_ip4n,
+                                      dst_address_length=0,
+                                      table_id=0,
+                                      next_hop_sw_if_index=cls.pg1.sw_if_index,
+                                      next_hop_address=cls.pg1.local_ip4n)
+
+            cls.pg5.resolve_arp()
+            cls.pg6.resolve_arp()
+
+        except Exception:
+            super(TestNAT44EndpointDependent, cls).tearDownClass()
+            raise
+
+    def test_dynamic(self):
+        """ NAT44 dynamic translation test """
+
+        self.nat44_add_address(self.nat_addr)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
+
+        nat_config = self.vapi.nat_show_config()
+        self.assertEqual(1, nat_config.endpoint_dependent)
+
+        # in2out
+        pkts = self.create_stream_in(self.pg0, self.pg1)
+        self.pg0.add_stream(pkts)
+        self.pg_enable_capture(self.pg_interfaces)
+        self.pg_start()
+        capture = self.pg1.get_capture(len(pkts))
+        self.verify_capture_out(capture)
+
+        # out2in
+        pkts = self.create_stream_out(self.pg1)
+        self.pg1.add_stream(pkts)
+        self.pg_enable_capture(self.pg_interfaces)
+        self.pg_start()
+        capture = self.pg0.get_capture(len(pkts))
+        self.verify_capture_in(capture, self.pg0)
+
+    def test_forwarding(self):
+        """ NAT44 forwarding test """
+
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
+        self.vapi.nat44_forwarding_enable_disable(1)
+
+        real_ip = self.pg0.remote_ip4n
+        alias_ip = self.nat_addr_n
+        self.vapi.nat44_add_del_static_mapping(local_ip=real_ip,
+                                               external_ip=alias_ip)
+
+        try:
+            # in2out - static mapping match
+
+            pkts = self.create_stream_out(self.pg1)
+            self.pg1.add_stream(pkts)
+            self.pg_enable_capture(self.pg_interfaces)
+            self.pg_start()
+            capture = self.pg0.get_capture(len(pkts))
+            self.verify_capture_in(capture, self.pg0)
+
+            pkts = self.create_stream_in(self.pg0, self.pg1)
+            self.pg0.add_stream(pkts)
+            self.pg_enable_capture(self.pg_interfaces)
+            self.pg_start()
+            capture = self.pg1.get_capture(len(pkts))
+            self.verify_capture_out(capture, same_port=True)
+
+            # in2out - no static mapping match
+
+            host0 = self.pg0.remote_hosts[0]
+            self.pg0.remote_hosts[0] = self.pg0.remote_hosts[1]
+            try:
+                pkts = self.create_stream_out(self.pg1,
+                                              dst_ip=self.pg0.remote_ip4,
+                                              use_inside_ports=True)
+                self.pg1.add_stream(pkts)
+                self.pg_enable_capture(self.pg_interfaces)
+                self.pg_start()
+                capture = self.pg0.get_capture(len(pkts))
+                self.verify_capture_in(capture, self.pg0)
+
+                pkts = self.create_stream_in(self.pg0, self.pg1)
+                self.pg0.add_stream(pkts)
+                self.pg_enable_capture(self.pg_interfaces)
+                self.pg_start()
+                capture = self.pg1.get_capture(len(pkts))
+                self.verify_capture_out(capture, nat_ip=self.pg0.remote_ip4,
+                                        same_port=True)
+            finally:
+                self.pg0.remote_hosts[0] = host0
+
+            user = self.pg0.remote_hosts[1]
+            sessions = self.vapi.nat44_user_session_dump(user.ip4n, 0)
+            self.assertEqual(len(sessions), 3)
+            self.assertTrue(sessions[0].ext_host_valid)
+            self.vapi.nat44_del_session(
+                sessions[0].inside_ip_address,
+                sessions[0].inside_port,
+                sessions[0].protocol,
+                ext_host_address=sessions[0].ext_host_address,
+                ext_host_port=sessions[0].ext_host_port)
+            sessions = self.vapi.nat44_user_session_dump(user.ip4n, 0)
+            self.assertEqual(len(sessions), 2)
+
+        finally:
+            self.vapi.nat44_forwarding_enable_disable(0)
+            self.vapi.nat44_add_del_static_mapping(local_ip=real_ip,
+                                                   external_ip=alias_ip,
+                                                   is_add=0)
+
+    def test_static_lb(self):
+        """ NAT44 local service load balancing """
+        external_addr_n = socket.inet_pton(socket.AF_INET, self.nat_addr)
+        external_port = 80
+        local_port = 8080
+        server1 = self.pg0.remote_hosts[0]
+        server2 = self.pg0.remote_hosts[1]
+
+        locals = [{'addr': server1.ip4n,
+                   'port': local_port,
+                   'probability': 70,
+                   'vrf_id': 0},
+                  {'addr': server2.ip4n,
+                   'port': local_port,
+                   'probability': 30,
+                   'vrf_id': 0}]
+
+        self.nat44_add_address(self.nat_addr)
+        self.vapi.nat44_add_del_lb_static_mapping(external_addr_n,
+                                                  external_port,
+                                                  IP_PROTOS.tcp,
+                                                  local_num=len(locals),
+                                                  locals=locals)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
+
+        # from client to service
+        p = (Ether(src=self.pg1.remote_mac, dst=self.pg1.local_mac) /
+             IP(src=self.pg1.remote_ip4, dst=self.nat_addr) /
+             TCP(sport=12345, dport=external_port))
+        self.pg1.add_stream(p)
+        self.pg_enable_capture(self.pg_interfaces)
+        self.pg_start()
+        capture = self.pg0.get_capture(1)
+        p = capture[0]
+        server = None
+        try:
+            ip = p[IP]
+            tcp = p[TCP]
+            self.assertIn(ip.dst, [server1.ip4, server2.ip4])
+            if ip.dst == server1.ip4:
+                server = server1
+            else:
+                server = server2
+            self.assertEqual(tcp.dport, local_port)
+            self.assert_packet_checksums_valid(p)
+        except:
+            self.logger.error(ppp("Unexpected or invalid packet:", p))
+            raise
+
+        # from service back to client
+        p = (Ether(src=server.mac, dst=self.pg0.local_mac) /
+             IP(src=server.ip4, dst=self.pg1.remote_ip4) /
+             TCP(sport=local_port, dport=12345))
+        self.pg0.add_stream(p)
+        self.pg_enable_capture(self.pg_interfaces)
+        self.pg_start()
+        capture = self.pg1.get_capture(1)
+        p = capture[0]
+        try:
+            ip = p[IP]
+            tcp = p[TCP]
+            self.assertEqual(ip.src, self.nat_addr)
+            self.assertEqual(tcp.sport, external_port)
+            self.assert_packet_checksums_valid(p)
+        except:
+            self.logger.error(ppp("Unexpected or invalid packet:", p))
+            raise
+
+        sessions = self.vapi.nat44_user_session_dump(server.ip4n, 0)
+        self.assertEqual(len(sessions), 1)
+        self.assertTrue(sessions[0].ext_host_valid)
+        self.vapi.nat44_del_session(
+            sessions[0].inside_ip_address,
+            sessions[0].inside_port,
+            sessions[0].protocol,
+            ext_host_address=sessions[0].ext_host_address,
+            ext_host_port=sessions[0].ext_host_port)
+        sessions = self.vapi.nat44_user_session_dump(server.ip4n, 0)
+        self.assertEqual(len(sessions), 0)
+
+    @unittest.skipUnless(running_extended_tests(), "part of extended tests")
+    def test_static_lb_multi_clients(self):
+        """ NAT44 local service load balancing - multiple clients"""
+
+        external_addr_n = socket.inet_pton(socket.AF_INET, self.nat_addr)
+        external_port = 80
+        local_port = 8080
+        server1 = self.pg0.remote_hosts[0]
+        server2 = self.pg0.remote_hosts[1]
+
+        locals = [{'addr': server1.ip4n,
+                   'port': local_port,
+                   'probability': 90,
+                   'vrf_id': 0},
+                  {'addr': server2.ip4n,
+                   'port': local_port,
+                   'probability': 10,
+                   'vrf_id': 0}]
+
+        self.nat44_add_address(self.nat_addr)
+        self.vapi.nat44_add_del_lb_static_mapping(external_addr_n,
+                                                  external_port,
+                                                  IP_PROTOS.tcp,
+                                                  local_num=len(locals),
+                                                  locals=locals)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
+
+        server1_n = 0
+        server2_n = 0
+        clients = ip4_range(self.pg1.remote_ip4, 10, 50)
+        pkts = []
+        for client in clients:
+            p = (Ether(src=self.pg1.remote_mac, dst=self.pg1.local_mac) /
+                 IP(src=client, dst=self.nat_addr) /
+                 TCP(sport=12345, dport=external_port))
+            pkts.append(p)
+        self.pg1.add_stream(pkts)
+        self.pg_enable_capture(self.pg_interfaces)
+        self.pg_start()
+        capture = self.pg0.get_capture(len(pkts))
+        for p in capture:
+            if p[IP].dst == server1.ip4:
+                server1_n += 1
+            else:
+                server2_n += 1
+        self.assertTrue(server1_n > server2_n)
+
+    def test_static_lb_2(self):
+        """ NAT44 local service load balancing (asymmetrical rule) """
+        external_addr_n = socket.inet_pton(socket.AF_INET, self.nat_addr)
+        external_port = 80
+        local_port = 8080
+        server1 = self.pg0.remote_hosts[0]
+        server2 = self.pg0.remote_hosts[1]
+
+        locals = [{'addr': server1.ip4n,
+                   'port': local_port,
+                   'probability': 70,
+                   'vrf_id': 0},
+                  {'addr': server2.ip4n,
+                   'port': local_port,
+                   'probability': 30,
+                   'vrf_id': 0}]
+
+        self.vapi.nat44_forwarding_enable_disable(1)
+        self.vapi.nat44_add_del_lb_static_mapping(external_addr_n,
+                                                  external_port,
+                                                  IP_PROTOS.tcp,
+                                                  out2in_only=1,
+                                                  local_num=len(locals),
+                                                  locals=locals)
         self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
         self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
                                                   is_inside=0)
 
         self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
         self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
                                                   is_inside=0)
 
-        # in2out
-        p = (Ether(dst=self.pg0.local_mac, src=self.pg0.remote_mac) /
-             IP(src=self.pg0.remote_ip4, dst=self.pg1.remote_ip4) /
-             GRE() /
-             IP(src=self.pg2.remote_ip4, dst=self.pg3.remote_ip4) /
-             TCP(sport=1234, dport=1234))
-        self.pg0.add_stream(p)
+        # from client to service
+        p = (Ether(src=self.pg1.remote_mac, dst=self.pg1.local_mac) /
+             IP(src=self.pg1.remote_ip4, dst=self.nat_addr) /
+             TCP(sport=12345, dport=external_port))
+        self.pg1.add_stream(p)
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
-        p = self.pg1.get_capture(1)
-        packet = p[0]
+        capture = self.pg0.get_capture(1)
+        p = capture[0]
+        server = None
         try:
         try:
-            self.assertEqual(packet[IP].src, nat_ip)
-            self.assertEqual(packet[IP].dst, self.pg1.remote_ip4)
-            self.assertTrue(packet.haslayer(GRE))
-            self.check_ip_checksum(packet)
+            ip = p[IP]
+            tcp = p[TCP]
+            self.assertIn(ip.dst, [server1.ip4, server2.ip4])
+            if ip.dst == server1.ip4:
+                server = server1
+            else:
+                server = server2
+            self.assertEqual(tcp.dport, local_port)
+            self.assert_packet_checksums_valid(p)
         except:
         except:
-            self.logger.error(ppp("Unexpected or invalid packet:", packet))
+            self.logger.error(ppp("Unexpected or invalid packet:", p))
             raise
 
             raise
 
-        # out2in
-        p = (Ether(dst=self.pg1.local_mac, src=self.pg1.remote_mac) /
-             IP(src=self.pg1.remote_ip4, dst=nat_ip) /
-             GRE() /
-             IP(src=self.pg3.remote_ip4, dst=self.pg2.remote_ip4) /
-             TCP(sport=1234, dport=1234))
-        self.pg1.add_stream(p)
+        # from service back to client
+        p = (Ether(src=server.mac, dst=self.pg0.local_mac) /
+             IP(src=server.ip4, dst=self.pg1.remote_ip4) /
+             TCP(sport=local_port, dport=12345))
+        self.pg0.add_stream(p)
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
-        p = self.pg0.get_capture(1)
-        packet = p[0]
+        capture = self.pg1.get_capture(1)
+        p = capture[0]
         try:
         try:
-            self.assertEqual(packet[IP].src, self.pg1.remote_ip4)
-            self.assertEqual(packet[IP].dst, self.pg0.remote_ip4)
-            self.assertTrue(packet.haslayer(GRE))
-            self.check_ip_checksum(packet)
+            ip = p[IP]
+            tcp = p[TCP]
+            self.assertEqual(ip.src, self.nat_addr)
+            self.assertEqual(tcp.sport, external_port)
+            self.assert_packet_checksums_valid(p)
         except:
         except:
-            self.logger.error(ppp("Unexpected or invalid packet:", packet))
+            self.logger.error(ppp("Unexpected or invalid packet:", p))
             raise
 
             raise
 
-    def test_hairpinning_static_unknown_proto(self):
-        """ 1:1 NAT translate packet with unknown protocol - hairpinning """
-
-        host = self.pg0.remote_hosts[0]
-        server = self.pg0.remote_hosts[1]
-
-        host_nat_ip = "10.0.0.10"
-        server_nat_ip = "10.0.0.11"
-
-        self.nat44_add_static_mapping(host.ip4, host_nat_ip)
-        self.nat44_add_static_mapping(server.ip4, server_nat_ip)
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
-                                                  is_inside=0)
-
-        # host to server
-        p = (Ether(dst=self.pg0.local_mac, src=host.mac) /
-             IP(src=host.ip4, dst=server_nat_ip) /
-             GRE() /
-             IP(src=self.pg2.remote_ip4, dst=self.pg3.remote_ip4) /
-             TCP(sport=1234, dport=1234))
-        self.pg0.add_stream(p)
+        # from client to server (no translation)
+        p = (Ether(src=self.pg1.remote_mac, dst=self.pg1.local_mac) /
+             IP(src=self.pg1.remote_ip4, dst=server1.ip4) /
+             TCP(sport=12346, dport=local_port))
+        self.pg1.add_stream(p)
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
-        p = self.pg0.get_capture(1)
-        packet = p[0]
+        capture = self.pg0.get_capture(1)
+        p = capture[0]
+        server = None
         try:
         try:
-            self.assertEqual(packet[IP].src, host_nat_ip)
-            self.assertEqual(packet[IP].dst, server.ip4)
-            self.assertTrue(packet.haslayer(GRE))
-            self.check_ip_checksum(packet)
+            ip = p[IP]
+            tcp = p[TCP]
+            self.assertEqual(ip.dst, server1.ip4)
+            self.assertEqual(tcp.dport, local_port)
+            self.assert_packet_checksums_valid(p)
         except:
         except:
-            self.logger.error(ppp("Unexpected or invalid packet:", packet))
+            self.logger.error(ppp("Unexpected or invalid packet:", p))
             raise
 
             raise
 
-        # server to host
-        p = (Ether(dst=self.pg0.local_mac, src=server.mac) /
-             IP(src=server.ip4, dst=host_nat_ip) /
-             GRE() /
-             IP(src=self.pg3.remote_ip4, dst=self.pg2.remote_ip4) /
-             TCP(sport=1234, dport=1234))
+        # from service back to client (no translation)
+        p = (Ether(src=server1.mac, dst=self.pg0.local_mac) /
+             IP(src=server1.ip4, dst=self.pg1.remote_ip4) /
+             TCP(sport=local_port, dport=12346))
         self.pg0.add_stream(p)
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
         self.pg0.add_stream(p)
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
-        p = self.pg0.get_capture(1)
-        packet = p[0]
+        capture = self.pg1.get_capture(1)
+        p = capture[0]
         try:
         try:
-            self.assertEqual(packet[IP].src, server_nat_ip)
-            self.assertEqual(packet[IP].dst, host.ip4)
-            self.assertTrue(packet.haslayer(GRE))
-            self.check_ip_checksum(packet)
+            ip = p[IP]
+            tcp = p[TCP]
+            self.assertEqual(ip.src, server1.ip4)
+            self.assertEqual(tcp.sport, local_port)
+            self.assert_packet_checksums_valid(p)
         except:
         except:
-            self.logger.error(ppp("Unexpected or invalid packet:", packet))
+            self.logger.error(ppp("Unexpected or invalid packet:", p))
             raise
 
     def test_unknown_proto(self):
             raise
 
     def test_unknown_proto(self):
@@ -3019,7 +3760,7 @@ class TestNAT44(MethodHolder):
         p = (Ether(dst=self.pg0.local_mac, src=self.pg0.remote_mac) /
              IP(src=self.pg0.remote_ip4, dst=self.pg1.remote_ip4) /
              GRE() /
         p = (Ether(dst=self.pg0.local_mac, src=self.pg0.remote_mac) /
              IP(src=self.pg0.remote_ip4, dst=self.pg1.remote_ip4) /
              GRE() /
-             IP(src=self.pg2.remote_ip4, dst=self.pg3.remote_ip4) /
+             IP(src=self.pg2.remote_ip4, dst=self.pg2.remote_ip4) /
              TCP(sport=1234, dport=1234))
         self.pg0.add_stream(p)
         self.pg_enable_capture(self.pg_interfaces)
              TCP(sport=1234, dport=1234))
         self.pg0.add_stream(p)
         self.pg_enable_capture(self.pg_interfaces)
@@ -3030,7 +3771,7 @@ class TestNAT44(MethodHolder):
             self.assertEqual(packet[IP].src, self.nat_addr)
             self.assertEqual(packet[IP].dst, self.pg1.remote_ip4)
             self.assertTrue(packet.haslayer(GRE))
             self.assertEqual(packet[IP].src, self.nat_addr)
             self.assertEqual(packet[IP].dst, self.pg1.remote_ip4)
             self.assertTrue(packet.haslayer(GRE))
-            self.check_ip_checksum(packet)
+            self.assert_packet_checksums_valid(packet)
         except:
             self.logger.error(ppp("Unexpected or invalid packet:", packet))
             raise
         except:
             self.logger.error(ppp("Unexpected or invalid packet:", packet))
             raise
@@ -3039,7 +3780,7 @@ class TestNAT44(MethodHolder):
         p = (Ether(dst=self.pg1.local_mac, src=self.pg1.remote_mac) /
              IP(src=self.pg1.remote_ip4, dst=self.nat_addr) /
              GRE() /
         p = (Ether(dst=self.pg1.local_mac, src=self.pg1.remote_mac) /
              IP(src=self.pg1.remote_ip4, dst=self.nat_addr) /
              GRE() /
-             IP(src=self.pg3.remote_ip4, dst=self.pg2.remote_ip4) /
+             IP(src=self.pg2.remote_ip4, dst=self.pg2.remote_ip4) /
              TCP(sport=1234, dport=1234))
         self.pg1.add_stream(p)
         self.pg_enable_capture(self.pg_interfaces)
              TCP(sport=1234, dport=1234))
         self.pg1.add_stream(p)
         self.pg_enable_capture(self.pg_interfaces)
@@ -3050,7 +3791,7 @@ class TestNAT44(MethodHolder):
             self.assertEqual(packet[IP].src, self.pg1.remote_ip4)
             self.assertEqual(packet[IP].dst, self.pg0.remote_ip4)
             self.assertTrue(packet.haslayer(GRE))
             self.assertEqual(packet[IP].src, self.pg1.remote_ip4)
             self.assertEqual(packet[IP].dst, self.pg0.remote_ip4)
             self.assertTrue(packet.haslayer(GRE))
-            self.check_ip_checksum(packet)
+            self.assert_packet_checksums_valid(packet)
         except:
             self.logger.error(ppp("Unexpected or invalid packet:", packet))
             raise
         except:
             self.logger.error(ppp("Unexpected or invalid packet:", packet))
             raise
@@ -3060,8 +3801,6 @@ class TestNAT44(MethodHolder):
         host = self.pg0.remote_hosts[0]
         server = self.pg0.remote_hosts[1]
         host_in_port = 1234
         host = self.pg0.remote_hosts[0]
         server = self.pg0.remote_hosts[1]
         host_in_port = 1234
-        host_out_port = 0
-        server_in_port = 5678
         server_out_port = 8765
         server_nat_ip = "10.0.0.11"
 
         server_out_port = 8765
         server_nat_ip = "10.0.0.11"
 
@@ -3080,12 +3819,12 @@ class TestNAT44(MethodHolder):
         self.pg0.add_stream(p)
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
         self.pg0.add_stream(p)
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
-        capture = self.pg0.get_capture(1)
+        self.pg0.get_capture(1)
 
         p = (Ether(dst=self.pg0.local_mac, src=host.mac) /
              IP(src=host.ip4, dst=server_nat_ip) /
              GRE() /
 
         p = (Ether(dst=self.pg0.local_mac, src=host.mac) /
              IP(src=host.ip4, dst=server_nat_ip) /
              GRE() /
-             IP(src=self.pg2.remote_ip4, dst=self.pg3.remote_ip4) /
+             IP(src=self.pg2.remote_ip4, dst=self.pg2.remote_ip4) /
              TCP(sport=1234, dport=1234))
         self.pg0.add_stream(p)
         self.pg_enable_capture(self.pg_interfaces)
              TCP(sport=1234, dport=1234))
         self.pg0.add_stream(p)
         self.pg_enable_capture(self.pg_interfaces)
@@ -3096,7 +3835,7 @@ class TestNAT44(MethodHolder):
             self.assertEqual(packet[IP].src, self.nat_addr)
             self.assertEqual(packet[IP].dst, server.ip4)
             self.assertTrue(packet.haslayer(GRE))
             self.assertEqual(packet[IP].src, self.nat_addr)
             self.assertEqual(packet[IP].dst, server.ip4)
             self.assertTrue(packet.haslayer(GRE))
-            self.check_ip_checksum(packet)
+            self.assert_packet_checksums_valid(packet)
         except:
             self.logger.error(ppp("Unexpected or invalid packet:", packet))
             raise
         except:
             self.logger.error(ppp("Unexpected or invalid packet:", packet))
             raise
@@ -3105,7 +3844,7 @@ class TestNAT44(MethodHolder):
         p = (Ether(dst=self.pg0.local_mac, src=server.mac) /
              IP(src=server.ip4, dst=self.nat_addr) /
              GRE() /
         p = (Ether(dst=self.pg0.local_mac, src=server.mac) /
              IP(src=server.ip4, dst=self.nat_addr) /
              GRE() /
-             IP(src=self.pg3.remote_ip4, dst=self.pg2.remote_ip4) /
+             IP(src=self.pg2.remote_ip4, dst=self.pg2.remote_ip4) /
              TCP(sport=1234, dport=1234))
         self.pg0.add_stream(p)
         self.pg_enable_capture(self.pg_interfaces)
              TCP(sport=1234, dport=1234))
         self.pg0.add_stream(p)
         self.pg_enable_capture(self.pg_interfaces)
@@ -3116,144 +3855,173 @@ class TestNAT44(MethodHolder):
             self.assertEqual(packet[IP].src, server_nat_ip)
             self.assertEqual(packet[IP].dst, host.ip4)
             self.assertTrue(packet.haslayer(GRE))
             self.assertEqual(packet[IP].src, server_nat_ip)
             self.assertEqual(packet[IP].dst, host.ip4)
             self.assertTrue(packet.haslayer(GRE))
-            self.check_ip_checksum(packet)
+            self.assert_packet_checksums_valid(packet)
         except:
             self.logger.error(ppp("Unexpected or invalid packet:", packet))
             raise
 
         except:
             self.logger.error(ppp("Unexpected or invalid packet:", packet))
             raise
 
-    def test_output_feature(self):
-        """ NAT44 interface output feature (in2out postrouting) """
+    def test_output_feature_and_service(self):
+        """ NAT44 interface output feature and services """
+        external_addr = '1.2.3.4'
+        external_port = 80
+        local_port = 8080
+
+        self.vapi.nat44_forwarding_enable_disable(1)
         self.nat44_add_address(self.nat_addr)
         self.nat44_add_address(self.nat_addr)
-        self.vapi.nat44_interface_add_del_output_feature(self.pg0.sw_if_index)
-        self.vapi.nat44_interface_add_del_output_feature(self.pg1.sw_if_index)
-        self.vapi.nat44_interface_add_del_output_feature(self.pg3.sw_if_index,
+        self.vapi.nat44_add_del_identity_mapping(ip=self.pg1.remote_ip4n)
+        self.nat44_add_static_mapping(self.pg0.remote_ip4, external_addr,
+                                      local_port, external_port,
+                                      proto=IP_PROTOS.tcp, out2in_only=1)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
+                                                  is_inside=0)
+        self.vapi.nat44_interface_add_del_output_feature(self.pg1.sw_if_index,
                                                          is_inside=0)
 
                                                          is_inside=0)
 
-        # in2out
-        pkts = self.create_stream_in(self.pg0, self.pg3)
+        # from client to service
+        p = (Ether(src=self.pg1.remote_mac, dst=self.pg1.local_mac) /
+             IP(src=self.pg1.remote_ip4, dst=external_addr) /
+             TCP(sport=12345, dport=external_port))
+        self.pg1.add_stream(p)
+        self.pg_enable_capture(self.pg_interfaces)
+        self.pg_start()
+        capture = self.pg0.get_capture(1)
+        p = capture[0]
+        try:
+            ip = p[IP]
+            tcp = p[TCP]
+            self.assertEqual(ip.dst, self.pg0.remote_ip4)
+            self.assertEqual(tcp.dport, local_port)
+            self.assert_packet_checksums_valid(p)
+        except:
+            self.logger.error(ppp("Unexpected or invalid packet:", p))
+            raise
+
+        # from service back to client
+        p = (Ether(src=self.pg0.remote_mac, dst=self.pg0.local_mac) /
+             IP(src=self.pg0.remote_ip4, dst=self.pg1.remote_ip4) /
+             TCP(sport=local_port, dport=12345))
+        self.pg0.add_stream(p)
+        self.pg_enable_capture(self.pg_interfaces)
+        self.pg_start()
+        capture = self.pg1.get_capture(1)
+        p = capture[0]
+        try:
+            ip = p[IP]
+            tcp = p[TCP]
+            self.assertEqual(ip.src, external_addr)
+            self.assertEqual(tcp.sport, external_port)
+            self.assert_packet_checksums_valid(p)
+        except:
+            self.logger.error(ppp("Unexpected or invalid packet:", p))
+            raise
+
+        # from local network host to external network
+        pkts = self.create_stream_in(self.pg0, self.pg1)
         self.pg0.add_stream(pkts)
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
         self.pg0.add_stream(pkts)
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
-        capture = self.pg3.get_capture(len(pkts))
+        capture = self.pg1.get_capture(len(pkts))
         self.verify_capture_out(capture)
         self.verify_capture_out(capture)
-
-        # out2in
-        pkts = self.create_stream_out(self.pg3)
-        self.pg3.add_stream(pkts)
+        pkts = self.create_stream_in(self.pg0, self.pg1)
+        self.pg0.add_stream(pkts)
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
-        capture = self.pg0.get_capture(len(pkts))
-        self.verify_capture_in(capture, self.pg0)
+        capture = self.pg1.get_capture(len(pkts))
+        self.verify_capture_out(capture)
 
 
-        # from non-NAT interface to NAT inside interface
-        pkts = self.create_stream_in(self.pg2, self.pg0)
-        self.pg2.add_stream(pkts)
+        # from external network back to local network host
+        pkts = self.create_stream_out(self.pg1)
+        self.pg1.add_stream(pkts)
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
         capture = self.pg0.get_capture(len(pkts))
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
         capture = self.pg0.get_capture(len(pkts))
-        self.verify_capture_no_translation(capture, self.pg2, self.pg0)
-
-    def test_output_feature_vrf_aware(self):
-        """ NAT44 interface output feature VRF aware (in2out postrouting) """
-        nat_ip_vrf10 = "10.0.0.10"
-        nat_ip_vrf20 = "10.0.0.20"
-
-        self.vapi.ip_add_del_route(dst_address=self.pg3.remote_ip4n,
-                                   dst_address_length=32,
-                                   next_hop_address=self.pg3.remote_ip4n,
-                                   next_hop_sw_if_index=self.pg3.sw_if_index,
-                                   table_id=10)
-        self.vapi.ip_add_del_route(dst_address=self.pg3.remote_ip4n,
-                                   dst_address_length=32,
-                                   next_hop_address=self.pg3.remote_ip4n,
-                                   next_hop_sw_if_index=self.pg3.sw_if_index,
-                                   table_id=20)
+        self.verify_capture_in(capture, self.pg0)
 
 
-        self.nat44_add_address(nat_ip_vrf10, vrf_id=10)
-        self.nat44_add_address(nat_ip_vrf20, vrf_id=20)
-        self.vapi.nat44_interface_add_del_output_feature(self.pg4.sw_if_index)
-        self.vapi.nat44_interface_add_del_output_feature(self.pg6.sw_if_index)
-        self.vapi.nat44_interface_add_del_output_feature(self.pg3.sw_if_index,
+    def test_output_feature_and_service2(self):
+        """ NAT44 interface output feature and service host direct access """
+        self.vapi.nat44_forwarding_enable_disable(1)
+        self.nat44_add_address(self.nat_addr)
+        self.vapi.nat44_interface_add_del_output_feature(self.pg1.sw_if_index,
                                                          is_inside=0)
 
                                                          is_inside=0)
 
-        # in2out VRF 10
-        pkts = self.create_stream_in(self.pg4, self.pg3)
-        self.pg4.add_stream(pkts)
+        # session initiaded from service host - translate
+        pkts = self.create_stream_in(self.pg0, self.pg1)
+        self.pg0.add_stream(pkts)
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
-        capture = self.pg3.get_capture(len(pkts))
-        self.verify_capture_out(capture, nat_ip=nat_ip_vrf10)
+        capture = self.pg1.get_capture(len(pkts))
+        self.verify_capture_out(capture)
 
 
-        # out2in VRF 10
-        pkts = self.create_stream_out(self.pg3, dst_ip=nat_ip_vrf10)
-        self.pg3.add_stream(pkts)
+        pkts = self.create_stream_out(self.pg1)
+        self.pg1.add_stream(pkts)
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
-        capture = self.pg4.get_capture(len(pkts))
-        self.verify_capture_in(capture, self.pg4)
+        capture = self.pg0.get_capture(len(pkts))
+        self.verify_capture_in(capture, self.pg0)
 
 
-        # in2out VRF 20
-        pkts = self.create_stream_in(self.pg6, self.pg3)
-        self.pg6.add_stream(pkts)
+        # session initiaded from remote host - do not translate
+        self.tcp_port_in = 60303
+        self.udp_port_in = 60304
+        self.icmp_id_in = 60305
+        pkts = self.create_stream_out(self.pg1,
+                                      self.pg0.remote_ip4,
+                                      use_inside_ports=True)
+        self.pg1.add_stream(pkts)
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
-        capture = self.pg3.get_capture(len(pkts))
-        self.verify_capture_out(capture, nat_ip=nat_ip_vrf20)
+        capture = self.pg0.get_capture(len(pkts))
+        self.verify_capture_in(capture, self.pg0)
 
 
-        # out2in VRF 20
-        pkts = self.create_stream_out(self.pg3, dst_ip=nat_ip_vrf20)
-        self.pg3.add_stream(pkts)
+        pkts = self.create_stream_in(self.pg0, self.pg1)
+        self.pg0.add_stream(pkts)
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
-        capture = self.pg6.get_capture(len(pkts))
-        self.verify_capture_in(capture, self.pg6)
+        capture = self.pg1.get_capture(len(pkts))
+        self.verify_capture_out(capture, nat_ip=self.pg0.remote_ip4,
+                                same_port=True)
 
 
-    def test_output_feature_hairpinning(self):
-        """ NAT44 interface output feature hairpinning (in2out postrouting) """
-        host = self.pg0.remote_hosts[0]
-        server = self.pg0.remote_hosts[1]
-        host_in_port = 1234
-        host_out_port = 0
-        server_in_port = 5678
-        server_out_port = 8765
+    def test_output_feature_and_service3(self):
+        """ NAT44 interface output feature and DST NAT """
+        external_addr = '1.2.3.4'
+        external_port = 80
+        local_port = 8080
 
 
+        self.vapi.nat44_forwarding_enable_disable(1)
         self.nat44_add_address(self.nat_addr)
         self.nat44_add_address(self.nat_addr)
-        self.vapi.nat44_interface_add_del_output_feature(self.pg0.sw_if_index)
+        self.nat44_add_static_mapping(self.pg1.remote_ip4, external_addr,
+                                      local_port, external_port,
+                                      proto=IP_PROTOS.tcp, out2in_only=1)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
+                                                  is_inside=0)
         self.vapi.nat44_interface_add_del_output_feature(self.pg1.sw_if_index,
                                                          is_inside=0)
 
         self.vapi.nat44_interface_add_del_output_feature(self.pg1.sw_if_index,
                                                          is_inside=0)
 
-        # add static mapping for server
-        self.nat44_add_static_mapping(server.ip4, self.nat_addr,
-                                      server_in_port, server_out_port,
-                                      proto=IP_PROTOS.tcp)
-
-        # send packet from host to server
-        p = (Ether(src=host.mac, dst=self.pg0.local_mac) /
-             IP(src=host.ip4, dst=self.nat_addr) /
-             TCP(sport=host_in_port, dport=server_out_port))
+        p = (Ether(src=self.pg0.remote_mac, dst=self.pg0.local_mac) /
+             IP(src=self.pg0.remote_ip4, dst=external_addr) /
+             TCP(sport=12345, dport=external_port))
         self.pg0.add_stream(p)
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
         self.pg0.add_stream(p)
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
-        capture = self.pg0.get_capture(1)
+        capture = self.pg1.get_capture(1)
         p = capture[0]
         try:
             ip = p[IP]
             tcp = p[TCP]
         p = capture[0]
         try:
             ip = p[IP]
             tcp = p[TCP]
-            self.assertEqual(ip.src, self.nat_addr)
-            self.assertEqual(ip.dst, server.ip4)
-            self.assertNotEqual(tcp.sport, host_in_port)
-            self.assertEqual(tcp.dport, server_in_port)
-            self.check_tcp_checksum(p)
-            host_out_port = tcp.sport
+            self.assertEqual(ip.src, self.pg0.remote_ip4)
+            self.assertEqual(tcp.sport, 12345)
+            self.assertEqual(ip.dst, self.pg1.remote_ip4)
+            self.assertEqual(tcp.dport, local_port)
+            self.assert_packet_checksums_valid(p)
         except:
             self.logger.error(ppp("Unexpected or invalid packet:", p))
             raise
 
         except:
             self.logger.error(ppp("Unexpected or invalid packet:", p))
             raise
 
-        # send reply from server to host
-        p = (Ether(src=server.mac, dst=self.pg0.local_mac) /
-             IP(src=server.ip4, dst=self.nat_addr) /
-             TCP(sport=server_in_port, dport=host_out_port))
-        self.pg0.add_stream(p)
+        p = (Ether(src=self.pg1.remote_mac, dst=self.pg1.local_mac) /
+             IP(src=self.pg1.remote_ip4, dst=self.pg0.remote_ip4) /
+             TCP(sport=local_port, dport=12345))
+        self.pg1.add_stream(p)
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
         capture = self.pg0.get_capture(1)
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
         capture = self.pg0.get_capture(1)
@@ -3261,174 +4029,448 @@ class TestNAT44(MethodHolder):
         try:
             ip = p[IP]
             tcp = p[TCP]
         try:
             ip = p[IP]
             tcp = p[TCP]
-            self.assertEqual(ip.src, self.nat_addr)
-            self.assertEqual(ip.dst, host.ip4)
-            self.assertEqual(tcp.sport, server_out_port)
-            self.assertEqual(tcp.dport, host_in_port)
-            self.check_tcp_checksum(p)
+            self.assertEqual(ip.src, external_addr)
+            self.assertEqual(tcp.sport, external_port)
+            self.assertEqual(ip.dst, self.pg0.remote_ip4)
+            self.assertEqual(tcp.dport, 12345)
+            self.assert_packet_checksums_valid(p)
         except:
             self.logger.error(ppp("Unexpected or invalid packet:", p))
             raise
 
         except:
             self.logger.error(ppp("Unexpected or invalid packet:", p))
             raise
 
-    def test_output_feature_and_service(self):
-        """ NAT44 interface output feature and services """
-        external_addr = '1.2.3.4'
+    def test_next_src_nat(self):
+        """ On way back forward packet to nat44-in2out node. """
+        twice_nat_addr = '10.0.1.3'
         external_port = 80
         local_port = 8080
         external_port = 80
         local_port = 8080
+        post_twice_nat_port = 0
 
         self.vapi.nat44_forwarding_enable_disable(1)
 
         self.vapi.nat44_forwarding_enable_disable(1)
-        self.nat44_add_address(self.nat_addr)
-        self.nat44_add_static_mapping(self.pg0.remote_ip4, external_addr,
+        self.nat44_add_address(twice_nat_addr, twice_nat=1)
+        self.nat44_add_static_mapping(self.pg6.remote_ip4, self.pg1.remote_ip4,
                                       local_port, external_port,
                                       local_port, external_port,
-                                      proto=IP_PROTOS.tcp, out2in_only=1)
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
-        self.vapi.nat44_interface_add_del_output_feature(self.pg1.sw_if_index,
-                                                         is_inside=0)
+                                      proto=IP_PROTOS.tcp, out2in_only=1,
+                                      self_twice_nat=1, vrf_id=1)
+        self.vapi.nat44_interface_add_del_feature(self.pg6.sw_if_index,
+                                                  is_inside=0)
 
 
-        # from client to service
-        p = (Ether(src=self.pg1.remote_mac, dst=self.pg1.local_mac) /
-             IP(src=self.pg1.remote_ip4, dst=external_addr) /
+        p = (Ether(src=self.pg6.remote_mac, dst=self.pg6.local_mac) /
+             IP(src=self.pg6.remote_ip4, dst=self.pg1.remote_ip4) /
              TCP(sport=12345, dport=external_port))
              TCP(sport=12345, dport=external_port))
-        self.pg1.add_stream(p)
+        self.pg6.add_stream(p)
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
-        capture = self.pg0.get_capture(1)
+        capture = self.pg6.get_capture(1)
         p = capture[0]
         p = capture[0]
-        server = None
         try:
             ip = p[IP]
             tcp = p[TCP]
         try:
             ip = p[IP]
             tcp = p[TCP]
-            self.assertEqual(ip.dst, self.pg0.remote_ip4)
+            self.assertEqual(ip.src, twice_nat_addr)
+            self.assertNotEqual(tcp.sport, 12345)
+            post_twice_nat_port = tcp.sport
+            self.assertEqual(ip.dst, self.pg6.remote_ip4)
             self.assertEqual(tcp.dport, local_port)
             self.assertEqual(tcp.dport, local_port)
-            self.check_tcp_checksum(p)
-            self.check_ip_checksum(p)
+            self.assert_packet_checksums_valid(p)
         except:
             self.logger.error(ppp("Unexpected or invalid packet:", p))
             raise
 
         except:
             self.logger.error(ppp("Unexpected or invalid packet:", p))
             raise
 
-        # from service back to client
-        p = (Ether(src=self.pg0.remote_mac, dst=self.pg0.local_mac) /
-             IP(src=self.pg0.remote_ip4, dst=self.pg1.remote_ip4) /
-             TCP(sport=local_port, dport=12345))
-        self.pg0.add_stream(p)
+        p = (Ether(src=self.pg6.remote_mac, dst=self.pg6.local_mac) /
+             IP(src=self.pg6.remote_ip4, dst=twice_nat_addr) /
+             TCP(sport=local_port, dport=post_twice_nat_port))
+        self.pg6.add_stream(p)
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
-        capture = self.pg1.get_capture(1)
+        capture = self.pg6.get_capture(1)
         p = capture[0]
         try:
             ip = p[IP]
             tcp = p[TCP]
         p = capture[0]
         try:
             ip = p[IP]
             tcp = p[TCP]
-            self.assertEqual(ip.src, external_addr)
+            self.assertEqual(ip.src, self.pg1.remote_ip4)
             self.assertEqual(tcp.sport, external_port)
             self.assertEqual(tcp.sport, external_port)
-            self.check_tcp_checksum(p)
-            self.check_ip_checksum(p)
+            self.assertEqual(ip.dst, self.pg6.remote_ip4)
+            self.assertEqual(tcp.dport, 12345)
+            self.assert_packet_checksums_valid(p)
         except:
             self.logger.error(ppp("Unexpected or invalid packet:", p))
             raise
 
         except:
             self.logger.error(ppp("Unexpected or invalid packet:", p))
             raise
 
-        # from local network host to external network
-        ext_port = 0
-        p = (Ether(src=self.pg0.remote_mac, dst=self.pg0.local_mac) /
-             IP(src=self.pg0.remote_ip4, dst=self.pg1.remote_ip4) /
-             TCP(sport=23456, dport=34567))
-        self.pg0.add_stream(p)
+    def twice_nat_common(self, self_twice_nat=False, same_pg=False, lb=False,
+                         client_id=None):
+        twice_nat_addr = '10.0.1.3'
+
+        port_in = 8080
+        if lb:
+            if not same_pg:
+                port_in1 = port_in
+                port_in2 = port_in
+            else:
+                port_in1 = port_in+1
+                port_in2 = port_in+2
+
+        port_out = 80
+        eh_port_out = 4567
+
+        server1 = self.pg0.remote_hosts[0]
+        server2 = self.pg0.remote_hosts[1]
+        if lb and same_pg:
+            server2 = server1
+        if not lb:
+            server = server1
+
+        pg0 = self.pg0
+        if same_pg:
+            pg1 = self.pg0
+        else:
+            pg1 = self.pg1
+
+        eh_translate = ((not self_twice_nat) or (not lb and same_pg) or
+                        client_id == 1)
+
+        self.nat44_add_address(self.nat_addr)
+        self.nat44_add_address(twice_nat_addr, twice_nat=1)
+        if not lb:
+            self.nat44_add_static_mapping(pg0.remote_ip4, self.nat_addr,
+                                          port_in, port_out,
+                                          proto=IP_PROTOS.tcp,
+                                          twice_nat=int(not self_twice_nat),
+                                          self_twice_nat=int(self_twice_nat))
+        else:
+            locals = [{'addr': server1.ip4n,
+                       'port': port_in1,
+                       'probability': 50,
+                       'vrf_id': 0},
+                      {'addr': server2.ip4n,
+                       'port': port_in2,
+                       'probability': 50,
+                       'vrf_id': 0}]
+            out_addr_n = socket.inet_pton(socket.AF_INET, self.nat_addr)
+            self.vapi.nat44_add_del_lb_static_mapping(out_addr_n,
+                                                      port_out,
+                                                      IP_PROTOS.tcp,
+                                                      twice_nat=int(
+                                                          not self_twice_nat),
+                                                      self_twice_nat=int(
+                                                          self_twice_nat),
+                                                      local_num=len(locals),
+                                                      locals=locals)
+        self.vapi.nat44_interface_add_del_feature(pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(pg1.sw_if_index,
+                                                  is_inside=0)
+
+        if same_pg:
+            if not lb:
+                client = server
+            else:
+                assert client_id is not None
+                if client_id == 1:
+                    client = self.pg0.remote_hosts[0]
+                elif client_id == 2:
+                    client = self.pg0.remote_hosts[1]
+        else:
+            client = pg1.remote_hosts[0]
+        p = (Ether(src=pg1.remote_mac, dst=pg1.local_mac) /
+             IP(src=client.ip4, dst=self.nat_addr) /
+             TCP(sport=eh_port_out, dport=port_out))
+        pg1.add_stream(p)
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
-        capture = self.pg1.get_capture(1)
+        capture = pg0.get_capture(1)
         p = capture[0]
         try:
             ip = p[IP]
             tcp = p[TCP]
         p = capture[0]
         try:
             ip = p[IP]
             tcp = p[TCP]
-            self.assertEqual(ip.src, self.nat_addr)
-            self.assertNotEqual(tcp.sport, 23456)
-            ext_port = tcp.sport
-            self.check_tcp_checksum(p)
-            self.check_ip_checksum(p)
+            if lb:
+                if ip.dst == server1.ip4:
+                    server = server1
+                    port_in = port_in1
+                else:
+                    server = server2
+                    port_in = port_in2
+            self.assertEqual(ip.dst, server.ip4)
+            if lb and same_pg:
+                self.assertIn(tcp.dport, [port_in1, port_in2])
+            else:
+                self.assertEqual(tcp.dport, port_in)
+            if eh_translate:
+                self.assertEqual(ip.src, twice_nat_addr)
+                self.assertNotEqual(tcp.sport, eh_port_out)
+            else:
+                self.assertEqual(ip.src, client.ip4)
+                self.assertEqual(tcp.sport, eh_port_out)
+            eh_addr_in = ip.src
+            eh_port_in = tcp.sport
+            saved_port_in = tcp.dport
+            self.assert_packet_checksums_valid(p)
         except:
             self.logger.error(ppp("Unexpected or invalid packet:", p))
             raise
 
         except:
             self.logger.error(ppp("Unexpected or invalid packet:", p))
             raise
 
-        # from external network back to local network host
-        p = (Ether(src=self.pg1.remote_mac, dst=self.pg1.local_mac) /
-             IP(src=self.pg1.remote_ip4, dst=self.nat_addr) /
-             TCP(sport=34567, dport=ext_port))
-        self.pg1.add_stream(p)
+        p = (Ether(src=server.mac, dst=pg0.local_mac) /
+             IP(src=server.ip4, dst=eh_addr_in) /
+             TCP(sport=saved_port_in, dport=eh_port_in))
+        pg0.add_stream(p)
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
-        capture = self.pg0.get_capture(1)
+        capture = pg1.get_capture(1)
         p = capture[0]
         p = capture[0]
-        server = None
         try:
             ip = p[IP]
             tcp = p[TCP]
         try:
             ip = p[IP]
             tcp = p[TCP]
-            self.assertEqual(ip.dst, self.pg0.remote_ip4)
-            self.assertEqual(tcp.dport, 23456)
-            self.check_tcp_checksum(p)
-            self.check_ip_checksum(p)
+            self.assertEqual(ip.dst, client.ip4)
+            self.assertEqual(ip.src, self.nat_addr)
+            self.assertEqual(tcp.dport, eh_port_out)
+            self.assertEqual(tcp.sport, port_out)
+            self.assert_packet_checksums_valid(p)
         except:
             self.logger.error(ppp("Unexpected or invalid packet:", p))
             raise
 
         except:
             self.logger.error(ppp("Unexpected or invalid packet:", p))
             raise
 
-    def test_one_armed_nat44(self):
-        """ One armed NAT44 """
-        remote_host = self.pg9.remote_hosts[0]
-        local_host = self.pg9.remote_hosts[1]
-        external_port = 0
+        if eh_translate:
+            sessions = self.vapi.nat44_user_session_dump(server.ip4n, 0)
+            self.assertEqual(len(sessions), 1)
+            self.assertTrue(sessions[0].ext_host_valid)
+            self.assertTrue(sessions[0].is_twicenat)
+            self.vapi.nat44_del_session(
+                sessions[0].inside_ip_address,
+                sessions[0].inside_port,
+                sessions[0].protocol,
+                ext_host_address=sessions[0].ext_host_nat_address,
+                ext_host_port=sessions[0].ext_host_nat_port)
+            sessions = self.vapi.nat44_user_session_dump(server.ip4n, 0)
+            self.assertEqual(len(sessions), 0)
+
+    def test_twice_nat(self):
+        """ Twice NAT44 """
+        self.twice_nat_common()
+
+    def test_self_twice_nat_positive(self):
+        """ Self Twice NAT44 (positive test) """
+        self.twice_nat_common(self_twice_nat=True, same_pg=True)
+
+    def test_self_twice_nat_negative(self):
+        """ Self Twice NAT44 (negative test) """
+        self.twice_nat_common(self_twice_nat=True)
+
+    def test_twice_nat_lb(self):
+        """ Twice NAT44 local service load balancing """
+        self.twice_nat_common(lb=True)
+
+    def test_self_twice_nat_lb_positive(self):
+        """ Self Twice NAT44 local service load balancing (positive test) """
+        self.twice_nat_common(lb=True, self_twice_nat=True, same_pg=True,
+                              client_id=1)
+
+    def test_self_twice_nat_lb_negative(self):
+        """ Self Twice NAT44 local service load balancing (negative test) """
+        self.twice_nat_common(lb=True, self_twice_nat=True, same_pg=True,
+                              client_id=2)
+
+    def test_twice_nat_interface_addr(self):
+        """ Acquire twice NAT44 addresses from interface """
+        self.vapi.nat44_add_interface_addr(self.pg3.sw_if_index, twice_nat=1)
+
+        # no address in NAT pool
+        adresses = self.vapi.nat44_address_dump()
+        self.assertEqual(0, len(adresses))
+
+        # configure interface address and check NAT address pool
+        self.pg3.config_ip4()
+        adresses = self.vapi.nat44_address_dump()
+        self.assertEqual(1, len(adresses))
+        self.assertEqual(adresses[0].ip_address[0:4], self.pg3.local_ip4n)
+        self.assertEqual(adresses[0].twice_nat, 1)
+
+        # remove interface address and check NAT address pool
+        self.pg3.unconfig_ip4()
+        adresses = self.vapi.nat44_address_dump()
+        self.assertEqual(0, len(adresses))
 
 
+    def test_tcp_session_close_in(self):
+        """ Close TCP session from inside network """
+        self.tcp_port_out = 10505
         self.nat44_add_address(self.nat_addr)
         self.nat44_add_address(self.nat_addr)
-        self.vapi.nat44_interface_add_del_feature(self.pg9.sw_if_index)
-        self.vapi.nat44_interface_add_del_feature(self.pg9.sw_if_index,
+        self.nat44_add_static_mapping(self.pg0.remote_ip4,
+                                      self.nat_addr,
+                                      self.tcp_port_in,
+                                      self.tcp_port_out,
+                                      proto=IP_PROTOS.tcp,
+                                      twice_nat=1)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
+
+        sessions = self.vapi.nat44_user_session_dump(self.pg0.remote_ip4n, 0)
+        start_sessnum = len(sessions)
+
+        self.initiate_tcp_session(self.pg0, self.pg1)
+
+        # FIN packet in -> out
+        p = (Ether(src=self.pg0.remote_mac, dst=self.pg0.local_mac) /
+             IP(src=self.pg0.remote_ip4, dst=self.pg1.remote_ip4) /
+             TCP(sport=self.tcp_port_in, dport=self.tcp_external_port,
+                 flags="FA", seq=100, ack=300))
+        self.pg0.add_stream(p)
+        self.pg_enable_capture(self.pg_interfaces)
+        self.pg_start()
+        self.pg1.get_capture(1)
+
+        pkts = []
+
+        # ACK packet out -> in
+        p = (Ether(src=self.pg1.remote_mac, dst=self.pg1.local_mac) /
+             IP(src=self.pg1.remote_ip4, dst=self.nat_addr) /
+             TCP(sport=self.tcp_external_port, dport=self.tcp_port_out,
+                 flags="A", seq=300, ack=101))
+        pkts.append(p)
+
+        # FIN packet out -> in
+        p = (Ether(src=self.pg1.remote_mac, dst=self.pg1.local_mac) /
+             IP(src=self.pg1.remote_ip4, dst=self.nat_addr) /
+             TCP(sport=self.tcp_external_port, dport=self.tcp_port_out,
+                 flags="FA", seq=300, ack=101))
+        pkts.append(p)
+
+        self.pg1.add_stream(pkts)
+        self.pg_enable_capture(self.pg_interfaces)
+        self.pg_start()
+        self.pg0.get_capture(2)
+
+        # ACK packet in -> out
+        p = (Ether(src=self.pg0.remote_mac, dst=self.pg0.local_mac) /
+             IP(src=self.pg0.remote_ip4, dst=self.pg1.remote_ip4) /
+             TCP(sport=self.tcp_port_in, dport=self.tcp_external_port,
+                 flags="A", seq=101, ack=301))
+        self.pg0.add_stream(p)
+        self.pg_enable_capture(self.pg_interfaces)
+        self.pg_start()
+        self.pg1.get_capture(1)
+
+        sessions = self.vapi.nat44_user_session_dump(self.pg0.remote_ip4n,
+                                                     0)
+        self.assertEqual(len(sessions) - start_sessnum, 0)
+
+    def test_tcp_session_close_out(self):
+        """ Close TCP session from outside network """
+        self.tcp_port_out = 10505
+        self.nat44_add_address(self.nat_addr)
+        self.nat44_add_static_mapping(self.pg0.remote_ip4,
+                                      self.nat_addr,
+                                      self.tcp_port_in,
+                                      self.tcp_port_out,
+                                      proto=IP_PROTOS.tcp,
+                                      twice_nat=1)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
+
+        sessions = self.vapi.nat44_user_session_dump(self.pg0.remote_ip4n, 0)
+        start_sessnum = len(sessions)
+
+        self.initiate_tcp_session(self.pg0, self.pg1)
+
+        # FIN packet out -> in
+        p = (Ether(src=self.pg1.remote_mac, dst=self.pg1.local_mac) /
+             IP(src=self.pg1.remote_ip4, dst=self.nat_addr) /
+             TCP(sport=self.tcp_external_port, dport=self.tcp_port_out,
+                 flags="FA", seq=100, ack=300))
+        self.pg1.add_stream(p)
+        self.pg_enable_capture(self.pg_interfaces)
+        self.pg_start()
+        self.pg0.get_capture(1)
+
+        # FIN+ACK packet in -> out
+        p = (Ether(src=self.pg0.remote_mac, dst=self.pg0.local_mac) /
+             IP(src=self.pg0.remote_ip4, dst=self.pg1.remote_ip4) /
+             TCP(sport=self.tcp_port_in, dport=self.tcp_external_port,
+                 flags="FA", seq=300, ack=101))
+
+        self.pg0.add_stream(p)
+        self.pg_enable_capture(self.pg_interfaces)
+        self.pg_start()
+        self.pg1.get_capture(1)
+
+        # ACK packet out -> in
+        p = (Ether(src=self.pg1.remote_mac, dst=self.pg1.local_mac) /
+             IP(src=self.pg1.remote_ip4, dst=self.nat_addr) /
+             TCP(sport=self.tcp_external_port, dport=self.tcp_port_out,
+                 flags="A", seq=101, ack=301))
+        self.pg1.add_stream(p)
+        self.pg_enable_capture(self.pg_interfaces)
+        self.pg_start()
+        self.pg0.get_capture(1)
+
+        sessions = self.vapi.nat44_user_session_dump(self.pg0.remote_ip4n,
+                                                     0)
+        self.assertEqual(len(sessions) - start_sessnum, 0)
+
+    def test_tcp_session_close_simultaneous(self):
+        """ Close TCP session from inside network """
+        self.tcp_port_out = 10505
+        self.nat44_add_address(self.nat_addr)
+        self.nat44_add_static_mapping(self.pg0.remote_ip4,
+                                      self.nat_addr,
+                                      self.tcp_port_in,
+                                      self.tcp_port_out,
+                                      proto=IP_PROTOS.tcp,
+                                      twice_nat=1)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
                                                   is_inside=0)
 
                                                   is_inside=0)
 
-        # in2out
-        p = (Ether(src=self.pg9.remote_mac, dst=self.pg9.local_mac) /
-             IP(src=local_host.ip4, dst=remote_host.ip4) /
-             TCP(sport=12345, dport=80))
-        self.pg9.add_stream(p)
+        sessions = self.vapi.nat44_user_session_dump(self.pg0.remote_ip4n, 0)
+        start_sessnum = len(sessions)
+
+        self.initiate_tcp_session(self.pg0, self.pg1)
+
+        # FIN packet in -> out
+        p = (Ether(src=self.pg0.remote_mac, dst=self.pg0.local_mac) /
+             IP(src=self.pg0.remote_ip4, dst=self.pg1.remote_ip4) /
+             TCP(sport=self.tcp_port_in, dport=self.tcp_external_port,
+                 flags="FA", seq=100, ack=300))
+        self.pg0.add_stream(p)
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
-        capture = self.pg9.get_capture(1)
-        p = capture[0]
-        try:
-            ip = p[IP]
-            tcp = p[TCP]
-            self.assertEqual(ip.src, self.nat_addr)
-            self.assertEqual(ip.dst, remote_host.ip4)
-            self.assertNotEqual(tcp.sport, 12345)
-            external_port = tcp.sport
-            self.assertEqual(tcp.dport, 80)
-            self.check_tcp_checksum(p)
-            self.check_ip_checksum(p)
-        except:
-            self.logger.error(ppp("Unexpected or invalid packet:", p))
-            raise
+        self.pg1.get_capture(1)
 
 
-        # out2in
-        p = (Ether(src=self.pg9.remote_mac, dst=self.pg9.local_mac) /
-             IP(src=remote_host.ip4, dst=self.nat_addr) /
-             TCP(sport=80, dport=external_port))
-        self.pg9.add_stream(p)
+        # FIN packet out -> in
+        p = (Ether(src=self.pg1.remote_mac, dst=self.pg1.local_mac) /
+             IP(src=self.pg1.remote_ip4, dst=self.nat_addr) /
+             TCP(sport=self.tcp_external_port, dport=self.tcp_port_out,
+                 flags="FA", seq=300, ack=100))
+        self.pg1.add_stream(p)
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
-        capture = self.pg9.get_capture(1)
-        p = capture[0]
-        try:
-            ip = p[IP]
-            tcp = p[TCP]
-            self.assertEqual(ip.src, remote_host.ip4)
-            self.assertEqual(ip.dst, local_host.ip4)
-            self.assertEqual(tcp.sport, 80)
-            self.assertEqual(tcp.dport, 12345)
-            self.check_tcp_checksum(p)
-            self.check_ip_checksum(p)
-        except:
-            self.logger.error(ppp("Unexpected or invalid packet:", p))
-            raise
+        self.pg0.get_capture(1)
+
+        # ACK packet in -> out
+        p = (Ether(src=self.pg0.remote_mac, dst=self.pg0.local_mac) /
+             IP(src=self.pg0.remote_ip4, dst=self.pg1.remote_ip4) /
+             TCP(sport=self.tcp_port_in, dport=self.tcp_external_port,
+                 flags="A", seq=101, ack=301))
+        self.pg0.add_stream(p)
+        self.pg_enable_capture(self.pg_interfaces)
+        self.pg_start()
+        self.pg1.get_capture(1)
+
+        # ACK packet out -> in
+        p = (Ether(src=self.pg1.remote_mac, dst=self.pg1.local_mac) /
+             IP(src=self.pg1.remote_ip4, dst=self.nat_addr) /
+             TCP(sport=self.tcp_external_port, dport=self.tcp_port_out,
+                 flags="A", seq=301, ack=101))
+        self.pg1.add_stream(p)
+        self.pg_enable_capture(self.pg_interfaces)
+        self.pg_start()
+        self.pg0.get_capture(1)
+
+        sessions = self.vapi.nat44_user_session_dump(self.pg0.remote_ip4n,
+                                                     0)
+        self.assertEqual(len(sessions) - start_sessnum, 0)
 
     def test_one_armed_nat44_static(self):
 
     def test_one_armed_nat44_static(self):
-        """ One armed NAT44 and 1:1 NAPT symmetrical rule """
-        remote_host = self.pg9.remote_hosts[0]
-        local_host = self.pg9.remote_hosts[1]
+        """ One armed NAT44 and 1:1 NAPT asymmetrical rule """
+        remote_host = self.pg4.remote_hosts[0]
+        local_host = self.pg4.remote_hosts[1]
         external_port = 80
         local_port = 8080
         eh_port_in = 0
         external_port = 80
         local_port = 8080
         eh_port_in = 0
@@ -3439,20 +4481,19 @@ class TestNAT44(MethodHolder):
                                       local_port, external_port,
                                       proto=IP_PROTOS.tcp, out2in_only=1,
                                       twice_nat=1)
                                       local_port, external_port,
                                       proto=IP_PROTOS.tcp, out2in_only=1,
                                       twice_nat=1)
-        self.vapi.nat44_interface_add_del_feature(self.pg9.sw_if_index)
-        self.vapi.nat44_interface_add_del_feature(self.pg9.sw_if_index,
+        self.vapi.nat44_interface_add_del_feature(self.pg4.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg4.sw_if_index,
                                                   is_inside=0)
 
         # from client to service
                                                   is_inside=0)
 
         # from client to service
-        p = (Ether(src=self.pg9.remote_mac, dst=self.pg9.local_mac) /
+        p = (Ether(src=self.pg4.remote_mac, dst=self.pg4.local_mac) /
              IP(src=remote_host.ip4, dst=self.nat_addr) /
              TCP(sport=12345, dport=external_port))
              IP(src=remote_host.ip4, dst=self.nat_addr) /
              TCP(sport=12345, dport=external_port))
-        self.pg9.add_stream(p)
+        self.pg4.add_stream(p)
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
-        capture = self.pg9.get_capture(1)
+        capture = self.pg4.get_capture(1)
         p = capture[0]
         p = capture[0]
-        server = None
         try:
             ip = p[IP]
             tcp = p[TCP]
         try:
             ip = p[IP]
             tcp = p[TCP]
@@ -3461,20 +4502,19 @@ class TestNAT44(MethodHolder):
             self.assertEqual(tcp.dport, local_port)
             self.assertNotEqual(tcp.sport, 12345)
             eh_port_in = tcp.sport
             self.assertEqual(tcp.dport, local_port)
             self.assertNotEqual(tcp.sport, 12345)
             eh_port_in = tcp.sport
-            self.check_tcp_checksum(p)
-            self.check_ip_checksum(p)
+            self.assert_packet_checksums_valid(p)
         except:
             self.logger.error(ppp("Unexpected or invalid packet:", p))
             raise
 
         # from service back to client
         except:
             self.logger.error(ppp("Unexpected or invalid packet:", p))
             raise
 
         # from service back to client
-        p = (Ether(src=self.pg9.remote_mac, dst=self.pg9.local_mac) /
+        p = (Ether(src=self.pg4.remote_mac, dst=self.pg4.local_mac) /
              IP(src=local_host.ip4, dst=self.nat_addr) /
              TCP(sport=local_port, dport=eh_port_in))
              IP(src=local_host.ip4, dst=self.nat_addr) /
              TCP(sport=local_port, dport=eh_port_in))
-        self.pg9.add_stream(p)
+        self.pg4.add_stream(p)
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
-        capture = self.pg9.get_capture(1)
+        capture = self.pg4.get_capture(1)
         p = capture[0]
         try:
             ip = p[IP]
         p = capture[0]
         try:
             ip = p[IP]
@@ -3483,205 +4523,232 @@ class TestNAT44(MethodHolder):
             self.assertEqual(ip.dst, remote_host.ip4)
             self.assertEqual(tcp.sport, external_port)
             self.assertEqual(tcp.dport, 12345)
             self.assertEqual(ip.dst, remote_host.ip4)
             self.assertEqual(tcp.sport, external_port)
             self.assertEqual(tcp.dport, 12345)
-            self.check_tcp_checksum(p)
-            self.check_ip_checksum(p)
+            self.assert_packet_checksums_valid(p)
         except:
             self.logger.error(ppp("Unexpected or invalid packet:", p))
             raise
 
         except:
             self.logger.error(ppp("Unexpected or invalid packet:", p))
             raise
 
-    def test_del_session(self):
-        """ Delete NAT44 session """
-        self.nat44_add_address(self.nat_addr)
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
-                                                  is_inside=0)
-
-        pkts = self.create_stream_in(self.pg0, self.pg1)
-        self.pg0.add_stream(pkts)
-        self.pg_enable_capture(self.pg_interfaces)
-        self.pg_start()
-        capture = self.pg1.get_capture(len(pkts))
-
-        sessions = self.vapi.nat44_user_session_dump(self.pg0.remote_ip4n, 0)
-        nsessions = len(sessions)
-
-        self.vapi.nat44_del_session(sessions[0].inside_ip_address,
-                                    sessions[0].inside_port,
-                                    sessions[0].protocol)
-        self.vapi.nat44_del_session(sessions[1].outside_ip_address,
-                                    sessions[1].outside_port,
-                                    sessions[1].protocol,
-                                    is_in=0)
-
-        sessions = self.vapi.nat44_user_session_dump(self.pg0.remote_ip4n, 0)
-        self.assertEqual(nsessions - len(sessions), 2)
-
-    def test_set_get_reass(self):
-        """ NAT44 set/get virtual fragmentation reassembly """
-        reas_cfg1 = self.vapi.nat_get_reass()
-
-        self.vapi.nat_set_reass(timeout=reas_cfg1.ip4_timeout + 5,
-                                max_reass=reas_cfg1.ip4_max_reass * 2,
-                                max_frag=reas_cfg1.ip4_max_frag * 2)
-
-        reas_cfg2 = self.vapi.nat_get_reass()
-
-        self.assertEqual(reas_cfg1.ip4_timeout + 5, reas_cfg2.ip4_timeout)
-        self.assertEqual(reas_cfg1.ip4_max_reass * 2, reas_cfg2.ip4_max_reass)
-        self.assertEqual(reas_cfg1.ip4_max_frag * 2, reas_cfg2.ip4_max_frag)
+    def test_static_with_port_out2(self):
+        """ 1:1 NAPT asymmetrical rule """
 
 
-        self.vapi.nat_set_reass(drop_frag=1)
-        self.assertTrue(self.vapi.nat_get_reass().ip4_drop_frag)
+        external_port = 80
+        local_port = 8080
 
 
-    def test_frag_in_order(self):
-        """ NAT44 translate fragments arriving in order """
-        self.nat44_add_address(self.nat_addr)
+        self.vapi.nat44_forwarding_enable_disable(1)
+        self.nat44_add_static_mapping(self.pg0.remote_ip4, self.nat_addr,
+                                      local_port, external_port,
+                                      proto=IP_PROTOS.tcp, out2in_only=1)
         self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
         self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
                                                   is_inside=0)
 
         self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
         self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
                                                   is_inside=0)
 
-        data = "A" * 4 + "B" * 16 + "C" * 3
-        self.tcp_port_in = random.randint(1025, 65535)
-
-        reass = self.vapi.nat_reass_dump()
-        reass_n_start = len(reass)
-
-        # in2out
-        pkts = self.create_stream_frag(self.pg0,
-                                       self.pg1.remote_ip4,
-                                       self.tcp_port_in,
-                                       20,
-                                       data)
-        self.pg0.add_stream(pkts)
+        # from client to service
+        p = (Ether(src=self.pg1.remote_mac, dst=self.pg1.local_mac) /
+             IP(src=self.pg1.remote_ip4, dst=self.nat_addr) /
+             TCP(sport=12345, dport=external_port))
+        self.pg1.add_stream(p)
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
-        frags = self.pg1.get_capture(len(pkts))
-        p = self.reass_frags_and_verify(frags,
-                                        self.nat_addr,
-                                        self.pg1.remote_ip4)
-        self.assertEqual(p[TCP].dport, 20)
-        self.assertNotEqual(p[TCP].sport, self.tcp_port_in)
-        self.tcp_port_out = p[TCP].sport
-        self.assertEqual(data, p[Raw].load)
+        capture = self.pg0.get_capture(1)
+        p = capture[0]
+        try:
+            ip = p[IP]
+            tcp = p[TCP]
+            self.assertEqual(ip.dst, self.pg0.remote_ip4)
+            self.assertEqual(tcp.dport, local_port)
+            self.assert_packet_checksums_valid(p)
+        except:
+            self.logger.error(ppp("Unexpected or invalid packet:", p))
+            raise
 
 
-        # out2in
-        pkts = self.create_stream_frag(self.pg1,
-                                       self.nat_addr,
-                                       20,
-                                       self.tcp_port_out,
-                                       data)
-        self.pg1.add_stream(pkts)
+        # ICMP error
+        p = (Ether(dst=self.pg0.local_mac, src=self.pg0.remote_mac) /
+             IP(src=self.pg0.remote_ip4, dst=self.pg1.remote_ip4) /
+             ICMP(type=11) / capture[0][IP])
+        self.pg0.add_stream(p)
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
-        frags = self.pg0.get_capture(len(pkts))
-        p = self.reass_frags_and_verify(frags,
-                                        self.pg1.remote_ip4,
-                                        self.pg0.remote_ip4)
-        self.assertEqual(p[TCP].sport, 20)
-        self.assertEqual(p[TCP].dport, self.tcp_port_in)
-        self.assertEqual(data, p[Raw].load)
-
-        reass = self.vapi.nat_reass_dump()
-        reass_n_end = len(reass)
+        capture = self.pg1.get_capture(1)
+        p = capture[0]
+        try:
+            self.assertEqual(p[IP].src, self.nat_addr)
+            inner = p[IPerror]
+            self.assertEqual(inner.dst, self.nat_addr)
+            self.assertEqual(inner[TCPerror].dport, external_port)
+        except:
+            self.logger.error(ppp("Unexpected or invalid packet:", p))
+            raise
 
 
-        self.assertEqual(reass_n_end - reass_n_start, 2)
+        # from service back to client
+        p = (Ether(src=self.pg0.remote_mac, dst=self.pg0.local_mac) /
+             IP(src=self.pg0.remote_ip4, dst=self.pg1.remote_ip4) /
+             TCP(sport=local_port, dport=12345))
+        self.pg0.add_stream(p)
+        self.pg_enable_capture(self.pg_interfaces)
+        self.pg_start()
+        capture = self.pg1.get_capture(1)
+        p = capture[0]
+        try:
+            ip = p[IP]
+            tcp = p[TCP]
+            self.assertEqual(ip.src, self.nat_addr)
+            self.assertEqual(tcp.sport, external_port)
+            self.assert_packet_checksums_valid(p)
+        except:
+            self.logger.error(ppp("Unexpected or invalid packet:", p))
+            raise
 
 
-    def test_reass_hairpinning(self):
-        """ NAT44 fragments hairpinning """
-        host = self.pg0.remote_hosts[0]
-        server = self.pg0.remote_hosts[1]
-        host_in_port = random.randint(1025, 65535)
-        host_out_port = 0
-        server_in_port = random.randint(1025, 65535)
-        server_out_port = random.randint(1025, 65535)
-        data = "A" * 4 + "B" * 16 + "C" * 3
+        # ICMP error
+        p = (Ether(dst=self.pg1.local_mac, src=self.pg1.remote_mac) /
+             IP(src=self.pg1.remote_ip4, dst=self.nat_addr) /
+             ICMP(type=11) / capture[0][IP])
+        self.pg1.add_stream(p)
+        self.pg_enable_capture(self.pg_interfaces)
+        self.pg_start()
+        capture = self.pg0.get_capture(1)
+        p = capture[0]
+        try:
+            self.assertEqual(p[IP].dst, self.pg0.remote_ip4)
+            inner = p[IPerror]
+            self.assertEqual(inner.src, self.pg0.remote_ip4)
+            self.assertEqual(inner[TCPerror].sport, local_port)
+        except:
+            self.logger.error(ppp("Unexpected or invalid packet:", p))
+            raise
 
 
-        self.nat44_add_address(self.nat_addr)
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
-                                                  is_inside=0)
-        # add static mapping for server
-        self.nat44_add_static_mapping(server.ip4, self.nat_addr,
-                                      server_in_port, server_out_port,
-                                      proto=IP_PROTOS.tcp)
+        # from client to server (no translation)
+        p = (Ether(src=self.pg1.remote_mac, dst=self.pg1.local_mac) /
+             IP(src=self.pg1.remote_ip4, dst=self.pg0.remote_ip4) /
+             TCP(sport=12346, dport=local_port))
+        self.pg1.add_stream(p)
+        self.pg_enable_capture(self.pg_interfaces)
+        self.pg_start()
+        capture = self.pg0.get_capture(1)
+        p = capture[0]
+        try:
+            ip = p[IP]
+            tcp = p[TCP]
+            self.assertEqual(ip.dst, self.pg0.remote_ip4)
+            self.assertEqual(tcp.dport, local_port)
+            self.assert_packet_checksums_valid(p)
+        except:
+            self.logger.error(ppp("Unexpected or invalid packet:", p))
+            raise
 
 
-        # send packet from host to server
-        pkts = self.create_stream_frag(self.pg0,
-                                       self.nat_addr,
-                                       host_in_port,
-                                       server_out_port,
-                                       data)
-        self.pg0.add_stream(pkts)
+        # from service back to client (no translation)
+        p = (Ether(src=self.pg0.remote_mac, dst=self.pg0.local_mac) /
+             IP(src=self.pg0.remote_ip4, dst=self.pg1.remote_ip4) /
+             TCP(sport=local_port, dport=12346))
+        self.pg0.add_stream(p)
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
-        frags = self.pg0.get_capture(len(pkts))
-        p = self.reass_frags_and_verify(frags,
-                                        self.nat_addr,
-                                        server.ip4)
-        self.assertNotEqual(p[TCP].sport, host_in_port)
-        self.assertEqual(p[TCP].dport, server_in_port)
-        self.assertEqual(data, p[Raw].load)
+        capture = self.pg1.get_capture(1)
+        p = capture[0]
+        try:
+            ip = p[IP]
+            tcp = p[TCP]
+            self.assertEqual(ip.src, self.pg0.remote_ip4)
+            self.assertEqual(tcp.sport, local_port)
+            self.assert_packet_checksums_valid(p)
+        except:
+            self.logger.error(ppp("Unexpected or invalid packet:", p))
+            raise
 
 
-    def test_frag_out_of_order(self):
-        """ NAT44 translate fragments arriving out of order """
+    def test_output_feature(self):
+        """ NAT44 interface output feature (in2out postrouting) """
+        self.vapi.nat44_forwarding_enable_disable(1)
         self.nat44_add_address(self.nat_addr)
         self.nat44_add_address(self.nat_addr)
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
                                                   is_inside=0)
                                                   is_inside=0)
-
-        data = "A" * 4 + "B" * 16 + "C" * 3
-        random.randint(1025, 65535)
+        self.vapi.nat44_interface_add_del_output_feature(self.pg1.sw_if_index,
+                                                         is_inside=0)
 
         # in2out
 
         # in2out
-        pkts = self.create_stream_frag(self.pg0,
-                                       self.pg1.remote_ip4,
-                                       self.tcp_port_in,
-                                       20,
-                                       data)
-        pkts.reverse()
+        pkts = self.create_stream_in(self.pg0, self.pg1)
         self.pg0.add_stream(pkts)
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
         self.pg0.add_stream(pkts)
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
-        frags = self.pg1.get_capture(len(pkts))
-        p = self.reass_frags_and_verify(frags,
-                                        self.nat_addr,
-                                        self.pg1.remote_ip4)
-        self.assertEqual(p[TCP].dport, 20)
-        self.assertNotEqual(p[TCP].sport, self.tcp_port_in)
-        self.tcp_port_out = p[TCP].sport
-        self.assertEqual(data, p[Raw].load)
+        capture = self.pg1.get_capture(len(pkts))
+        self.verify_capture_out(capture)
 
         # out2in
 
         # out2in
-        pkts = self.create_stream_frag(self.pg1,
-                                       self.nat_addr,
-                                       20,
-                                       self.tcp_port_out,
-                                       data)
-        pkts.reverse()
+        pkts = self.create_stream_out(self.pg1)
         self.pg1.add_stream(pkts)
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
         self.pg1.add_stream(pkts)
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
-        frags = self.pg0.get_capture(len(pkts))
-        p = self.reass_frags_and_verify(frags,
-                                        self.pg1.remote_ip4,
-                                        self.pg0.remote_ip4)
-        self.assertEqual(p[TCP].sport, 20)
-        self.assertEqual(p[TCP].dport, self.tcp_port_in)
-        self.assertEqual(data, p[Raw].load)
+        capture = self.pg0.get_capture(len(pkts))
+        self.verify_capture_in(capture, self.pg0)
 
 
-    def test_port_restricted(self):
-        """ Port restricted NAT44 (MAP-E CE) """
+    def test_multiple_vrf(self):
+        """ Multiple VRF setup """
+        external_addr = '1.2.3.4'
+        external_port = 80
+        local_port = 8080
+        port = 0
+
+        self.vapi.nat44_forwarding_enable_disable(1)
         self.nat44_add_address(self.nat_addr)
         self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
         self.nat44_add_address(self.nat_addr)
         self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index,
                                                   is_inside=0)
                                                   is_inside=0)
-        self.vapi.cli("nat addr-port-assignment-alg map-e psid 10 "
-                      "psid-offset 6 psid-len 6")
+        self.vapi.nat44_interface_add_del_output_feature(self.pg1.sw_if_index,
+                                                         is_inside=0)
+        self.vapi.nat44_interface_add_del_feature(self.pg5.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg5.sw_if_index,
+                                                  is_inside=0)
+        self.vapi.nat44_interface_add_del_feature(self.pg6.sw_if_index,
+                                                  is_inside=0)
+        self.nat44_add_static_mapping(self.pg5.remote_ip4, external_addr,
+                                      local_port, external_port, vrf_id=1,
+                                      proto=IP_PROTOS.tcp, out2in_only=1)
+        self.nat44_add_static_mapping(
+             self.pg0.remote_ip4, external_sw_if_index=self.pg0.sw_if_index,
+             local_port=local_port, vrf_id=0, external_port=external_port,
+             proto=IP_PROTOS.tcp, out2in_only=1)
 
 
-        p = (Ether(src=self.pg0.remote_mac, dst=self.pg0.local_mac) /
-             IP(src=self.pg0.remote_ip4, dst=self.pg1.remote_ip4) /
-             TCP(sport=4567, dport=22))
-        self.pg0.add_stream(p)
+        # from client to service (both VRF1)
+        p = (Ether(src=self.pg6.remote_mac, dst=self.pg6.local_mac) /
+             IP(src=self.pg6.remote_ip4, dst=external_addr) /
+             TCP(sport=12345, dport=external_port))
+        self.pg6.add_stream(p)
+        self.pg_enable_capture(self.pg_interfaces)
+        self.pg_start()
+        capture = self.pg5.get_capture(1)
+        p = capture[0]
+        try:
+            ip = p[IP]
+            tcp = p[TCP]
+            self.assertEqual(ip.dst, self.pg5.remote_ip4)
+            self.assertEqual(tcp.dport, local_port)
+            self.assert_packet_checksums_valid(p)
+        except:
+            self.logger.error(ppp("Unexpected or invalid packet:", p))
+            raise
+
+        # from service back to client (both VRF1)
+        p = (Ether(src=self.pg5.remote_mac, dst=self.pg5.local_mac) /
+             IP(src=self.pg5.remote_ip4, dst=self.pg6.remote_ip4) /
+             TCP(sport=local_port, dport=12345))
+        self.pg5.add_stream(p)
+        self.pg_enable_capture(self.pg_interfaces)
+        self.pg_start()
+        capture = self.pg6.get_capture(1)
+        p = capture[0]
+        try:
+            ip = p[IP]
+            tcp = p[TCP]
+            self.assertEqual(ip.src, external_addr)
+            self.assertEqual(tcp.sport, external_port)
+            self.assert_packet_checksums_valid(p)
+        except:
+            self.logger.error(ppp("Unexpected or invalid packet:", p))
+            raise
+
+        # dynamic NAT from VRF1 to VRF0 (output-feature)
+        p = (Ether(src=self.pg5.remote_mac, dst=self.pg5.local_mac) /
+             IP(src=self.pg5.remote_ip4, dst=self.pg1.remote_ip4) /
+             TCP(sport=2345, dport=22))
+        self.pg5.add_stream(p)
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
         capture = self.pg1.get_capture(1)
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
         capture = self.pg1.get_capture(1)
@@ -3689,232 +4756,333 @@ class TestNAT44(MethodHolder):
         try:
             ip = p[IP]
             tcp = p[TCP]
         try:
             ip = p[IP]
             tcp = p[TCP]
-            self.assertEqual(ip.dst, self.pg1.remote_ip4)
             self.assertEqual(ip.src, self.nat_addr)
             self.assertEqual(ip.src, self.nat_addr)
-            self.assertEqual(tcp.dport, 22)
-            self.assertNotEqual(tcp.sport, 4567)
-            self.assertEqual((tcp.sport >> 6) & 63, 10)
-            self.check_tcp_checksum(p)
-            self.check_ip_checksum(p)
+            self.assertNotEqual(tcp.sport, 2345)
+            self.assert_packet_checksums_valid(p)
+            port = tcp.sport
         except:
             self.logger.error(ppp("Unexpected or invalid packet:", p))
             raise
 
         except:
             self.logger.error(ppp("Unexpected or invalid packet:", p))
             raise
 
-    def test_twice_nat(self):
-        """ Twice NAT44 """
-        twice_nat_addr = '10.0.1.3'
-        port_in = 8080
-        port_out = 80
-        eh_port_out = 4567
-        eh_port_in = 0
-        self.nat44_add_address(self.nat_addr)
-        self.nat44_add_address(twice_nat_addr, twice_nat=1)
-        self.nat44_add_static_mapping(self.pg0.remote_ip4, self.nat_addr,
-                                      port_in, port_out, proto=IP_PROTOS.tcp,
-                                      twice_nat=1)
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
-                                                  is_inside=0)
-
         p = (Ether(src=self.pg1.remote_mac, dst=self.pg1.local_mac) /
              IP(src=self.pg1.remote_ip4, dst=self.nat_addr) /
         p = (Ether(src=self.pg1.remote_mac, dst=self.pg1.local_mac) /
              IP(src=self.pg1.remote_ip4, dst=self.nat_addr) /
-             TCP(sport=eh_port_out, dport=port_out))
+             TCP(sport=22, dport=port))
         self.pg1.add_stream(p)
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
         self.pg1.add_stream(p)
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
+        capture = self.pg5.get_capture(1)
+        p = capture[0]
+        try:
+            ip = p[IP]
+            tcp = p[TCP]
+            self.assertEqual(ip.dst, self.pg5.remote_ip4)
+            self.assertEqual(tcp.dport, 2345)
+            self.assert_packet_checksums_valid(p)
+        except:
+            self.logger.error(ppp("Unexpected or invalid packet:", p))
+            raise
+
+        # from client VRF1 to service VRF0
+        p = (Ether(src=self.pg6.remote_mac, dst=self.pg6.local_mac) /
+             IP(src=self.pg6.remote_ip4, dst=self.pg0.local_ip4) /
+             TCP(sport=12346, dport=external_port))
+        self.pg6.add_stream(p)
+        self.pg_enable_capture(self.pg_interfaces)
+        self.pg_start()
         capture = self.pg0.get_capture(1)
         p = capture[0]
         try:
             ip = p[IP]
             tcp = p[TCP]
             self.assertEqual(ip.dst, self.pg0.remote_ip4)
         capture = self.pg0.get_capture(1)
         p = capture[0]
         try:
             ip = p[IP]
             tcp = p[TCP]
             self.assertEqual(ip.dst, self.pg0.remote_ip4)
-            self.assertEqual(ip.src, twice_nat_addr)
-            self.assertEqual(tcp.dport, port_in)
-            self.assertNotEqual(tcp.sport, eh_port_out)
-            eh_port_in = tcp.sport
-            self.check_tcp_checksum(p)
-            self.check_ip_checksum(p)
+            self.assertEqual(tcp.dport, local_port)
+            self.assert_packet_checksums_valid(p)
         except:
             self.logger.error(ppp("Unexpected or invalid packet:", p))
             raise
 
         except:
             self.logger.error(ppp("Unexpected or invalid packet:", p))
             raise
 
+        # from service VRF0 back to client VRF1
         p = (Ether(src=self.pg0.remote_mac, dst=self.pg0.local_mac) /
         p = (Ether(src=self.pg0.remote_mac, dst=self.pg0.local_mac) /
-             IP(src=self.pg0.remote_ip4, dst=twice_nat_addr) /
-             TCP(sport=port_in, dport=eh_port_in))
+             IP(src=self.pg0.remote_ip4, dst=self.pg6.remote_ip4) /
+             TCP(sport=local_port, dport=12346))
         self.pg0.add_stream(p)
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
         self.pg0.add_stream(p)
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
-        capture = self.pg1.get_capture(1)
+        capture = self.pg6.get_capture(1)
         p = capture[0]
         try:
             ip = p[IP]
             tcp = p[TCP]
         p = capture[0]
         try:
             ip = p[IP]
             tcp = p[TCP]
-            self.assertEqual(ip.dst, self.pg1.remote_ip4)
-            self.assertEqual(ip.src, self.nat_addr)
-            self.assertEqual(tcp.dport, eh_port_out)
-            self.assertEqual(tcp.sport, port_out)
-            self.check_tcp_checksum(p)
-            self.check_ip_checksum(p)
+            self.assertEqual(ip.src, self.pg0.local_ip4)
+            self.assertEqual(tcp.sport, external_port)
+            self.assert_packet_checksums_valid(p)
         except:
             self.logger.error(ppp("Unexpected or invalid packet:", p))
             raise
 
         except:
             self.logger.error(ppp("Unexpected or invalid packet:", p))
             raise
 
-    def test_twice_nat_lb(self):
-        """ Twice NAT44 local service load balancing """
-        external_addr_n = socket.inet_pton(socket.AF_INET, self.nat_addr)
-        twice_nat_addr = '10.0.1.3'
-        local_port = 8080
-        external_port = 80
-        eh_port_out = 4567
-        eh_port_in = 0
-        server1 = self.pg0.remote_hosts[0]
-        server2 = self.pg0.remote_hosts[1]
+        # from client VRF0 to service VRF1
+        p = (Ether(src=self.pg0.remote_mac, dst=self.pg0.local_mac) /
+             IP(src=self.pg0.remote_ip4, dst=external_addr) /
+             TCP(sport=12347, dport=external_port))
+        self.pg0.add_stream(p)
+        self.pg_enable_capture(self.pg_interfaces)
+        self.pg_start()
+        capture = self.pg5.get_capture(1)
+        p = capture[0]
+        try:
+            ip = p[IP]
+            tcp = p[TCP]
+            self.assertEqual(ip.dst, self.pg5.remote_ip4)
+            self.assertEqual(tcp.dport, local_port)
+            self.assert_packet_checksums_valid(p)
+        except:
+            self.logger.error(ppp("Unexpected or invalid packet:", p))
+            raise
 
 
-        locals = [{'addr': server1.ip4n,
-                   'port': local_port,
-                   'probability': 50},
-                  {'addr': server2.ip4n,
-                   'port': local_port,
-                   'probability': 50}]
+        # from service VRF1 back to client VRF0
+        p = (Ether(src=self.pg5.remote_mac, dst=self.pg5.local_mac) /
+             IP(src=self.pg5.remote_ip4, dst=self.pg0.remote_ip4) /
+             TCP(sport=local_port, dport=12347))
+        self.pg5.add_stream(p)
+        self.pg_enable_capture(self.pg_interfaces)
+        self.pg_start()
+        capture = self.pg0.get_capture(1)
+        p = capture[0]
+        try:
+            ip = p[IP]
+            tcp = p[TCP]
+            self.assertEqual(ip.src, external_addr)
+            self.assertEqual(tcp.sport, external_port)
+            self.assert_packet_checksums_valid(p)
+        except:
+            self.logger.error(ppp("Unexpected or invalid packet:", p))
+            raise
 
 
-        self.nat44_add_address(self.nat_addr)
-        self.nat44_add_address(twice_nat_addr, twice_nat=1)
+        # from client to server (both VRF1, no translation)
+        p = (Ether(src=self.pg6.remote_mac, dst=self.pg6.local_mac) /
+             IP(src=self.pg6.remote_ip4, dst=self.pg5.remote_ip4) /
+             TCP(sport=12348, dport=local_port))
+        self.pg6.add_stream(p)
+        self.pg_enable_capture(self.pg_interfaces)
+        self.pg_start()
+        capture = self.pg5.get_capture(1)
+        p = capture[0]
+        try:
+            ip = p[IP]
+            tcp = p[TCP]
+            self.assertEqual(ip.dst, self.pg5.remote_ip4)
+            self.assertEqual(tcp.dport, local_port)
+            self.assert_packet_checksums_valid(p)
+        except:
+            self.logger.error(ppp("Unexpected or invalid packet:", p))
+            raise
 
 
-        self.vapi.nat44_add_del_lb_static_mapping(external_addr_n,
-                                                  external_port,
-                                                  IP_PROTOS.tcp,
-                                                  twice_nat=1,
-                                                  local_num=len(locals),
-                                                  locals=locals)
-        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
-        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
-                                                  is_inside=0)
+        # from server back to client (both VRF1, no translation)
+        p = (Ether(src=self.pg5.remote_mac, dst=self.pg5.local_mac) /
+             IP(src=self.pg5.remote_ip4, dst=self.pg6.remote_ip4) /
+             TCP(sport=local_port, dport=12348))
+        self.pg5.add_stream(p)
+        self.pg_enable_capture(self.pg_interfaces)
+        self.pg_start()
+        capture = self.pg6.get_capture(1)
+        p = capture[0]
+        try:
+            ip = p[IP]
+            tcp = p[TCP]
+            self.assertEqual(ip.src, self.pg5.remote_ip4)
+            self.assertEqual(tcp.sport, local_port)
+            self.assert_packet_checksums_valid(p)
+        except:
+            self.logger.error(ppp("Unexpected or invalid packet:", p))
+            raise
+
+        # from client VRF1 to server VRF0 (no translation)
+        p = (Ether(src=self.pg0.remote_mac, dst=self.pg0.local_mac) /
+             IP(src=self.pg0.remote_ip4, dst=self.pg6.remote_ip4) /
+             TCP(sport=local_port, dport=12349))
+        self.pg0.add_stream(p)
+        self.pg_enable_capture(self.pg_interfaces)
+        self.pg_start()
+        capture = self.pg6.get_capture(1)
+        p = capture[0]
+        try:
+            ip = p[IP]
+            tcp = p[TCP]
+            self.assertEqual(ip.src, self.pg0.remote_ip4)
+            self.assertEqual(tcp.sport, local_port)
+            self.assert_packet_checksums_valid(p)
+        except:
+            self.logger.error(ppp("Unexpected or invalid packet:", p))
+            raise
+
+        # from server VRF0 back to client VRF1 (no translation)
+        p = (Ether(src=self.pg0.remote_mac, dst=self.pg0.local_mac) /
+             IP(src=self.pg0.remote_ip4, dst=self.pg6.remote_ip4) /
+             TCP(sport=local_port, dport=12349))
+        self.pg0.add_stream(p)
+        self.pg_enable_capture(self.pg_interfaces)
+        self.pg_start()
+        capture = self.pg6.get_capture(1)
+        p = capture[0]
+        try:
+            ip = p[IP]
+            tcp = p[TCP]
+            self.assertEqual(ip.src, self.pg0.remote_ip4)
+            self.assertEqual(tcp.sport, local_port)
+            self.assert_packet_checksums_valid(p)
+        except:
+            self.logger.error(ppp("Unexpected or invalid packet:", p))
+            raise
 
 
-        p = (Ether(src=self.pg1.remote_mac, dst=self.pg1.local_mac) /
-             IP(src=self.pg1.remote_ip4, dst=self.nat_addr) /
-             TCP(sport=eh_port_out, dport=external_port))
-        self.pg1.add_stream(p)
+        # from client VRF0 to server VRF1 (no translation)
+        p = (Ether(src=self.pg0.remote_mac, dst=self.pg0.local_mac) /
+             IP(src=self.pg0.remote_ip4, dst=self.pg5.remote_ip4) /
+             TCP(sport=12344, dport=local_port))
+        self.pg0.add_stream(p)
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
-        capture = self.pg0.get_capture(1)
+        capture = self.pg5.get_capture(1)
         p = capture[0]
         p = capture[0]
-        server = None
         try:
             ip = p[IP]
             tcp = p[TCP]
         try:
             ip = p[IP]
             tcp = p[TCP]
-            self.assertEqual(ip.src, twice_nat_addr)
-            self.assertIn(ip.dst, [server1.ip4, server2.ip4])
-            if ip.dst == server1.ip4:
-                server = server1
-            else:
-                server = server2
-            self.assertNotEqual(tcp.sport, eh_port_out)
-            eh_port_in = tcp.sport
+            self.assertEqual(ip.dst, self.pg5.remote_ip4)
             self.assertEqual(tcp.dport, local_port)
             self.assertEqual(tcp.dport, local_port)
-            self.check_tcp_checksum(p)
-            self.check_ip_checksum(p)
+            self.assert_packet_checksums_valid(p)
         except:
             self.logger.error(ppp("Unexpected or invalid packet:", p))
             raise
 
         except:
             self.logger.error(ppp("Unexpected or invalid packet:", p))
             raise
 
-        p = (Ether(src=server.mac, dst=self.pg0.local_mac) /
-             IP(src=server.ip4, dst=twice_nat_addr) /
-             TCP(sport=local_port, dport=eh_port_in))
-        self.pg0.add_stream(p)
+        # from server VRF1 back to client VRF0 (no translation)
+        p = (Ether(src=self.pg5.remote_mac, dst=self.pg5.local_mac) /
+             IP(src=self.pg5.remote_ip4, dst=self.pg0.remote_ip4) /
+             TCP(sport=local_port, dport=12344))
+        self.pg5.add_stream(p)
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
-        capture = self.pg1.get_capture(1)
+        capture = self.pg0.get_capture(1)
         p = capture[0]
         try:
             ip = p[IP]
             tcp = p[TCP]
         p = capture[0]
         try:
             ip = p[IP]
             tcp = p[TCP]
-            self.assertEqual(ip.src, self.nat_addr)
-            self.assertEqual(ip.dst, self.pg1.remote_ip4)
-            self.assertEqual(tcp.sport, external_port)
-            self.assertEqual(tcp.dport, eh_port_out)
-            self.check_tcp_checksum(p)
-            self.check_ip_checksum(p)
+            self.assertEqual(ip.src, self.pg5.remote_ip4)
+            self.assertEqual(tcp.sport, local_port)
+            self.assert_packet_checksums_valid(p)
         except:
             self.logger.error(ppp("Unexpected or invalid packet:", p))
             raise
 
         except:
             self.logger.error(ppp("Unexpected or invalid packet:", p))
             raise
 
-    def test_twice_nat_interface_addr(self):
-        """ Acquire twice NAT44 addresses from interface """
-        self.vapi.nat44_add_interface_addr(self.pg7.sw_if_index, twice_nat=1)
+    @unittest.skipUnless(running_extended_tests(), "part of extended tests")
+    def test_session_timeout(self):
+        """ NAT44 session timeouts """
+        self.nat44_add_address(self.nat_addr)
+        self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
+                                                  is_inside=0)
+        self.vapi.nat_set_timeouts(icmp=5)
 
 
-        # no address in NAT pool
-        adresses = self.vapi.nat44_address_dump()
-        self.assertEqual(0, len(adresses))
+        max_sessions = 1000
+        pkts = []
+        for i in range(0, max_sessions):
+            src = "10.10.%u.%u" % ((i & 0xFF00) >> 8, i & 0xFF)
+            p = (Ether(dst=self.pg0.local_mac, src=self.pg0.remote_mac) /
+                 IP(src=src, dst=self.pg1.remote_ip4) /
+                 ICMP(id=1025, type='echo-request'))
+            pkts.append(p)
+        self.pg0.add_stream(pkts)
+        self.pg_enable_capture(self.pg_interfaces)
+        self.pg_start()
+        self.pg1.get_capture(max_sessions)
 
 
-        # configure interface address and check NAT address pool
-        self.pg7.config_ip4()
-        adresses = self.vapi.nat44_address_dump()
-        self.assertEqual(1, len(adresses))
-        self.assertEqual(adresses[0].ip_address[0:4], self.pg7.local_ip4n)
-        self.assertEqual(adresses[0].twice_nat, 1)
+        sleep(10)
 
 
-        # remove interface address and check NAT address pool
-        self.pg7.unconfig_ip4()
-        adresses = self.vapi.nat44_address_dump()
-        self.assertEqual(0, len(adresses))
+        pkts = []
+        for i in range(0, max_sessions):
+            src = "10.10.%u.%u" % ((i & 0xFF00) >> 8, i & 0xFF)
+            p = (Ether(dst=self.pg0.local_mac, src=self.pg0.remote_mac) /
+                 IP(src=src, dst=self.pg1.remote_ip4) /
+                 ICMP(id=1026, type='echo-request'))
+            pkts.append(p)
+        self.pg0.add_stream(pkts)
+        self.pg_enable_capture(self.pg_interfaces)
+        self.pg_start()
+        self.pg1.get_capture(max_sessions)
 
 
-    def test_ipfix_max_frags(self):
-        """ IPFIX logging maximum fragments pending reassembly exceeded """
+        nsessions = 0
+        users = self.vapi.nat44_user_dump()
+        for user in users:
+            nsessions = nsessions + user.nsessions
+        self.assertLess(nsessions, 2 * max_sessions)
+
+    @unittest.skipUnless(running_extended_tests(), "part of extended tests")
+    def test_session_limit_per_user(self):
+        """ Maximum sessions per user limit """
         self.nat44_add_address(self.nat_addr)
         self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
         self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
                                                   is_inside=0)
         self.nat44_add_address(self.nat_addr)
         self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
         self.vapi.nat44_interface_add_del_feature(self.pg1.sw_if_index,
                                                   is_inside=0)
-        self.vapi.nat_set_reass(max_frag=0)
-        self.vapi.set_ipfix_exporter(collector_address=self.pg3.remote_ip4n,
-                                     src_address=self.pg3.local_ip4n,
+        self.vapi.set_ipfix_exporter(collector_address=self.pg2.remote_ip4n,
+                                     src_address=self.pg2.local_ip4n,
                                      path_mtu=512,
                                      template_interval=10)
                                      path_mtu=512,
                                      template_interval=10)
+
+        # get maximum number of translations per user
+        nat44_config = self.vapi.nat_show_config()
+
+        pkts = []
+        for port in range(0, nat44_config.max_translations_per_user):
+            p = (Ether(src=self.pg0.remote_mac, dst=self.pg0.local_mac) /
+                 IP(src=self.pg0.remote_ip4, dst=self.pg1.remote_ip4) /
+                 UDP(sport=1025 + port, dport=1025 + port))
+            pkts.append(p)
+
+        self.pg0.add_stream(pkts)
+        self.pg_enable_capture(self.pg_interfaces)
+        self.pg_start()
+        capture = self.pg1.get_capture(len(pkts))
+
         self.vapi.nat_ipfix(domain_id=self.ipfix_domain_id,
                             src_port=self.ipfix_src_port)
 
         self.vapi.nat_ipfix(domain_id=self.ipfix_domain_id,
                             src_port=self.ipfix_src_port)
 
-        data = "A" * 4 + "B" * 16 + "C" * 3
-        self.tcp_port_in = random.randint(1025, 65535)
-        pkts = self.create_stream_frag(self.pg0,
-                                       self.pg1.remote_ip4,
-                                       self.tcp_port_in,
-                                       20,
-                                       data)
-        self.pg0.add_stream(pkts[-1])
+        p = (Ether(src=self.pg0.remote_mac, dst=self.pg0.local_mac) /
+             IP(src=self.pg0.remote_ip4, dst=self.pg1.remote_ip4) /
+             UDP(sport=3001, dport=3002))
+        self.pg0.add_stream(p)
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
-        frags = self.pg1.get_capture(0)
+        capture = self.pg1.assert_nothing_captured()
+
+        # verify IPFIX logging
         self.vapi.cli("ipfix flush")  # FIXME this should be an API call
         self.vapi.cli("ipfix flush")  # FIXME this should be an API call
-        capture = self.pg3.get_capture(9)
+        sleep(1)
+        capture = self.pg2.get_capture(10)
         ipfix = IPFIXDecoder()
         # first load template
         for p in capture:
             self.assertTrue(p.haslayer(IPFIX))
         ipfix = IPFIXDecoder()
         # first load template
         for p in capture:
             self.assertTrue(p.haslayer(IPFIX))
-            self.assertEqual(p[IP].src, self.pg3.local_ip4)
-            self.assertEqual(p[IP].dst, self.pg3.remote_ip4)
-            self.assertEqual(p[UDP].sport, self.ipfix_src_port)
-            self.assertEqual(p[UDP].dport, 4739)
-            self.assertEqual(p[IPFIX].observationDomainID,
-                             self.ipfix_domain_id)
             if p.haslayer(Template):
                 ipfix.add_template(p.getlayer(Template))
         # verify events in data set
         for p in capture:
             if p.haslayer(Data):
                 data = ipfix.decode_data_set(p.getlayer(Set))
             if p.haslayer(Template):
                 ipfix.add_template(p.getlayer(Template))
         # verify events in data set
         for p in capture:
             if p.haslayer(Data):
                 data = ipfix.decode_data_set(p.getlayer(Set))
-                self.verify_ipfix_max_fragments_ip4(data, 0,
-                                                    self.pg0.remote_ip4n)
+                self.verify_ipfix_max_entries_per_user(
+                    data,
+                    nat44_config.max_translations_per_user,
+                    self.pg0.remote_ip4n)
 
     def tearDown(self):
 
     def tearDown(self):
-        super(TestNAT44, self).tearDown()
+        super(TestNAT44EndpointDependent, self).tearDown()
         if not self.vpp_dead:
             self.logger.info(self.vapi.cli("show nat44 addresses"))
             self.logger.info(self.vapi.cli("show nat44 interfaces"))
             self.logger.info(self.vapi.cli("show nat44 static mappings"))
             self.logger.info(self.vapi.cli("show nat44 interface address"))
             self.logger.info(self.vapi.cli("show nat44 sessions detail"))
         if not self.vpp_dead:
             self.logger.info(self.vapi.cli("show nat44 addresses"))
             self.logger.info(self.vapi.cli("show nat44 interfaces"))
             self.logger.info(self.vapi.cli("show nat44 static mappings"))
             self.logger.info(self.vapi.cli("show nat44 interface address"))
             self.logger.info(self.vapi.cli("show nat44 sessions detail"))
-            self.logger.info(self.vapi.cli("show nat virtual-reassembly"))
-            self.vapi.cli("nat addr-port-assignment-alg default")
+            self.logger.info(self.vapi.cli("show nat44 hash tables detail"))
+            self.logger.info(self.vapi.cli("show nat timeouts"))
             self.clear_nat44()
             self.clear_nat44()
+            self.vapi.cli("clear logging")
 
 
 class TestNAT44Out2InDPO(MethodHolder):
 
 
 class TestNAT44Out2InDPO(MethodHolder):
@@ -3928,6 +5096,7 @@ class TestNAT44Out2InDPO(MethodHolder):
     @classmethod
     def setUpClass(cls):
         super(TestNAT44Out2InDPO, cls).setUpClass()
     @classmethod
     def setUpClass(cls):
         super(TestNAT44Out2InDPO, cls).setUpClass()
+        cls.vapi.cli("set log class nat level debug")
 
         try:
             cls.tcp_port_in = 6303
 
         try:
             cls.tcp_port_in = 6303
@@ -3976,6 +5145,9 @@ class TestNAT44Out2InDPO(MethodHolder):
     def test_464xlat_ce(self):
         """ Test 464XLAT CE with NAT44 """
 
     def test_464xlat_ce(self):
         """ Test 464XLAT CE with NAT44 """
 
+        nat_config = self.vapi.nat_show_config()
+        self.assertEqual(1, nat_config.out2in_dpo)
+
         self.configure_xlat()
 
         self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
         self.configure_xlat()
 
         self.vapi.nat44_interface_add_del_feature(self.pg0.sw_if_index)
@@ -4045,6 +5217,7 @@ class TestDeterministicNAT(MethodHolder):
     @classmethod
     def setUpClass(cls):
         super(TestDeterministicNAT, cls).setUpClass()
     @classmethod
     def setUpClass(cls):
         super(TestDeterministicNAT, cls).setUpClass()
+        cls.vapi.cli("set log class nat level debug")
 
         try:
             cls.tcp_port_in = 6303
 
         try:
             cls.tcp_port_in = 6303
@@ -4155,67 +5328,6 @@ class TestDeterministicNAT(MethodHolder):
                                       "(outside network):", packet))
                 raise
 
                                       "(outside network):", packet))
                 raise
 
-    def initiate_tcp_session(self, in_if, out_if):
-        """
-        Initiates TCP session
-
-        :param in_if: Inside interface
-        :param out_if: Outside interface
-        """
-        try:
-            # SYN packet in->out
-            p = (Ether(src=in_if.remote_mac, dst=in_if.local_mac) /
-                 IP(src=in_if.remote_ip4, dst=out_if.remote_ip4) /
-                 TCP(sport=self.tcp_port_in, dport=self.tcp_external_port,
-                     flags="S"))
-            in_if.add_stream(p)
-            self.pg_enable_capture(self.pg_interfaces)
-            self.pg_start()
-            capture = out_if.get_capture(1)
-            p = capture[0]
-            self.tcp_port_out = p[TCP].sport
-
-            # SYN + ACK packet out->in
-            p = (Ether(src=out_if.remote_mac, dst=out_if.local_mac) /
-                 IP(src=out_if.remote_ip4, dst=self.nat_addr) /
-                 TCP(sport=self.tcp_external_port, dport=self.tcp_port_out,
-                     flags="SA"))
-            out_if.add_stream(p)
-            self.pg_enable_capture(self.pg_interfaces)
-            self.pg_start()
-            in_if.get_capture(1)
-
-            # ACK packet in->out
-            p = (Ether(src=in_if.remote_mac, dst=in_if.local_mac) /
-                 IP(src=in_if.remote_ip4, dst=out_if.remote_ip4) /
-                 TCP(sport=self.tcp_port_in, dport=self.tcp_external_port,
-                     flags="A"))
-            in_if.add_stream(p)
-            self.pg_enable_capture(self.pg_interfaces)
-            self.pg_start()
-            out_if.get_capture(1)
-
-        except:
-            self.logger.error("TCP 3 way handshake failed")
-            raise
-
-    def verify_ipfix_max_entries_per_user(self, data):
-        """
-        Verify IPFIX maximum entries per user exceeded event
-
-        :param data: Decoded IPFIX data records
-        """
-        self.assertEqual(1, len(data))
-        record = data[0]
-        # natEvent
-        self.assertEqual(ord(record[230]), 13)
-        # natQuotaExceededEvent
-        self.assertEqual('\x03\x00\x00\x00', record[466])
-        # maxEntriesPerUser
-        self.assertEqual('\xe8\x03\x00\x00', record[473])
-        # sourceIPv4Address
-        self.assertEqual(self.pg0.remote_ip4n, record[8])
-
     def test_deterministic_mode(self):
         """ NAT plugin run deterministic mode """
         in_addr = '172.16.255.0'
     def test_deterministic_mode(self):
         """ NAT plugin run deterministic mode """
         in_addr = '172.16.255.0'
@@ -4251,14 +5363,14 @@ class TestDeterministicNAT(MethodHolder):
 
     def test_set_timeouts(self):
         """ Set deterministic NAT timeouts """
 
     def test_set_timeouts(self):
         """ Set deterministic NAT timeouts """
-        timeouts_before = self.vapi.nat_det_get_timeouts()
+        timeouts_before = self.vapi.nat_get_timeouts()
 
 
-        self.vapi.nat_det_set_timeouts(timeouts_before.udp + 10,
-                                       timeouts_before.tcp_established + 10,
-                                       timeouts_before.tcp_transitory + 10,
-                                       timeouts_before.icmp + 10)
+        self.vapi.nat_set_timeouts(timeouts_before.udp + 10,
+                                   timeouts_before.tcp_established + 10,
+                                   timeouts_before.tcp_transitory + 10,
+                                   timeouts_before.icmp + 10)
 
 
-        timeouts_after = self.vapi.nat_det_get_timeouts()
+        timeouts_after = self.vapi.nat_get_timeouts()
 
         self.assertNotEqual(timeouts_before.udp, timeouts_after.udp)
         self.assertNotEqual(timeouts_before.icmp, timeouts_after.icmp)
 
         self.assertNotEqual(timeouts_before.udp, timeouts_after.udp)
         self.assertNotEqual(timeouts_before.icmp, timeouts_after.icmp)
@@ -4573,7 +5685,7 @@ class TestDeterministicNAT(MethodHolder):
                                                   is_inside=0)
 
         self.initiate_tcp_session(self.pg0, self.pg1)
                                                   is_inside=0)
 
         self.initiate_tcp_session(self.pg0, self.pg1)
-        self.vapi.nat_det_set_timeouts(5, 5, 5, 5)
+        self.vapi.nat_set_timeouts(5, 5, 5, 5)
         pkts = self.create_stream_in(self.pg0, self.pg1)
         self.pg0.add_stream(pkts)
         self.pg_enable_capture(self.pg_interfaces)
         pkts = self.create_stream_in(self.pg0, self.pg1)
         self.pg0.add_stream(pkts)
         self.pg_enable_capture(self.pg_interfaces)
@@ -4650,14 +5762,16 @@ class TestDeterministicNAT(MethodHolder):
         for p in capture:
             if p.haslayer(Data):
                 data = ipfix.decode_data_set(p.getlayer(Set))
         for p in capture:
             if p.haslayer(Data):
                 data = ipfix.decode_data_set(p.getlayer(Set))
-                self.verify_ipfix_max_entries_per_user(data)
+                self.verify_ipfix_max_entries_per_user(data,
+                                                       1000,
+                                                       self.pg0.remote_ip4n)
 
     def clear_nat_det(self):
         """
         Clear deterministic NAT configuration.
         """
         self.vapi.nat_ipfix(enable=0)
 
     def clear_nat_det(self):
         """
         Clear deterministic NAT configuration.
         """
         self.vapi.nat_ipfix(enable=0)
-        self.vapi.nat_det_set_timeouts()
+        self.vapi.nat_set_timeouts()
         deterministic_mappings = self.vapi.nat_det_map_dump()
         for dsm in deterministic_mappings:
             self.vapi.nat_det_add_del_map(dsm.in_addr,
         deterministic_mappings = self.vapi.nat_det_map_dump()
         for dsm in deterministic_mappings:
             self.vapi.nat_det_add_del_map(dsm.in_addr,
@@ -4676,10 +5790,9 @@ class TestDeterministicNAT(MethodHolder):
         super(TestDeterministicNAT, self).tearDown()
         if not self.vpp_dead:
             self.logger.info(self.vapi.cli("show nat44 interfaces"))
         super(TestDeterministicNAT, self).tearDown()
         if not self.vpp_dead:
             self.logger.info(self.vapi.cli("show nat44 interfaces"))
+            self.logger.info(self.vapi.cli("show nat timeouts"))
             self.logger.info(
                 self.vapi.cli("show nat44 deterministic mappings"))
             self.logger.info(
                 self.vapi.cli("show nat44 deterministic mappings"))
-            self.logger.info(
-                self.vapi.cli("show nat44 deterministic timeouts"))
             self.logger.info(
                 self.vapi.cli("show nat44 deterministic sessions"))
             self.clear_nat_det()
             self.logger.info(
                 self.vapi.cli("show nat44 deterministic sessions"))
             self.clear_nat_det()
@@ -4714,7 +5827,7 @@ class TestNAT64(MethodHolder):
             cls.ipfix_src_port = 4739
             cls.ipfix_domain_id = 1
 
             cls.ipfix_src_port = 4739
             cls.ipfix_domain_id = 1
 
-            cls.create_pg_interfaces(range(5))
+            cls.create_pg_interfaces(range(6))
             cls.ip6_interfaces = list(cls.pg_interfaces[0:1])
             cls.ip6_interfaces.append(cls.pg_interfaces[2])
             cls.ip4_interfaces = list(cls.pg_interfaces[1:2])
             cls.ip6_interfaces = list(cls.pg_interfaces[0:1])
             cls.ip6_interfaces.append(cls.pg_interfaces[2])
             cls.ip4_interfaces = list(cls.pg_interfaces[1:2])
@@ -4741,10 +5854,67 @@ class TestNAT64(MethodHolder):
             cls.pg3.config_ip6()
             cls.pg3.configure_ipv6_neighbors()
 
             cls.pg3.config_ip6()
             cls.pg3.configure_ipv6_neighbors()
 
+            cls.pg5.admin_up()
+            cls.pg5.config_ip6()
+
         except Exception:
             super(TestNAT64, cls).tearDownClass()
             raise
 
         except Exception:
             super(TestNAT64, cls).tearDownClass()
             raise
 
+    def test_nat64_inside_interface_handles_neighbor_advertisement(self):
+        """ NAT64 inside interface handles Neighbor Advertisement """
+
+        self.vapi.nat64_add_del_interface(self.pg5.sw_if_index)
+
+        # Try to send ping
+        ping = (Ether(dst=self.pg5.local_mac, src=self.pg5.remote_mac) /
+                IPv6(src=self.pg5.remote_ip6, dst=self.pg5.local_ip6) /
+                ICMPv6EchoRequest())
+        pkts = [ping]
+        self.pg5.add_stream(pkts)
+        self.pg_enable_capture(self.pg_interfaces)
+        self.pg_start()
+
+        # Wait for Neighbor Solicitation
+        capture = self.pg5.get_capture(len(pkts))
+        self.assertEqual(1, len(capture))
+        packet = capture[0]
+        try:
+            self.assertEqual(packet[IPv6].src, self.pg5.local_ip6)
+            self.assertTrue(packet.haslayer(ICMPv6ND_NS))
+            tgt = packet[ICMPv6ND_NS].tgt
+        except:
+            self.logger.error(ppp("Unexpected or invalid packet:", packet))
+            raise
+
+        # Send Neighbor Advertisement
+        p = (Ether(dst=self.pg5.local_mac, src=self.pg5.remote_mac) /
+             IPv6(src=self.pg5.remote_ip6, dst=self.pg5.local_ip6) /
+             ICMPv6ND_NA(tgt=tgt) /
+             ICMPv6NDOptDstLLAddr(lladdr=self.pg5.remote_mac))
+        pkts = [p]
+        self.pg5.add_stream(pkts)
+        self.pg_enable_capture(self.pg_interfaces)
+        self.pg_start()
+
+        # Try to send ping again
+        pkts = [ping]
+        self.pg5.add_stream(pkts)
+        self.pg_enable_capture(self.pg_interfaces)
+        self.pg_start()
+
+        # Wait for ping reply
+        capture = self.pg5.get_capture(len(pkts))
+        self.assertEqual(1, len(capture))
+        packet = capture[0]
+        try:
+            self.assertEqual(packet[IPv6].src, self.pg5.local_ip6)
+            self.assertEqual(packet[IPv6].dst, self.pg5.remote_ip6)
+            self.assertTrue(packet.haslayer(ICMPv6EchoReply))
+        except:
+            self.logger.error(ppp("Unexpected or invalid packet:", packet))
+            raise
+
     def test_pool(self):
         """ Add/delete address to NAT64 pool """
         nat_addr = socket.inet_pton(socket.AF_INET, '1.2.3.4')
     def test_pool(self):
         """ Add/delete address to NAT64 pool """
         nat_addr = socket.inet_pton(socket.AF_INET, '1.2.3.4')
@@ -4831,22 +6001,20 @@ class TestNAT64(MethodHolder):
     def test_set_timeouts(self):
         """ Set NAT64 timeouts """
         # verify default values
     def test_set_timeouts(self):
         """ Set NAT64 timeouts """
         # verify default values
-        timeouts = self.vapi.nat64_get_timeouts()
+        timeouts = self.vapi.nat_get_timeouts()
         self.assertEqual(timeouts.udp, 300)
         self.assertEqual(timeouts.icmp, 60)
         self.assertEqual(timeouts.udp, 300)
         self.assertEqual(timeouts.icmp, 60)
-        self.assertEqual(timeouts.tcp_trans, 240)
-        self.assertEqual(timeouts.tcp_est, 7440)
-        self.assertEqual(timeouts.tcp_incoming_syn, 6)
+        self.assertEqual(timeouts.tcp_transitory, 240)
+        self.assertEqual(timeouts.tcp_established, 7440)
 
         # set and verify custom values
 
         # set and verify custom values
-        self.vapi.nat64_set_timeouts(udp=200, icmp=30, tcp_trans=250,
-                                     tcp_est=7450, tcp_incoming_syn=10)
-        timeouts = self.vapi.nat64_get_timeouts()
+        self.vapi.nat_set_timeouts(udp=200, icmp=30, tcp_transitory=250,
+                                   tcp_established=7450)
+        timeouts = self.vapi.nat_get_timeouts()
         self.assertEqual(timeouts.udp, 200)
         self.assertEqual(timeouts.icmp, 30)
         self.assertEqual(timeouts.udp, 200)
         self.assertEqual(timeouts.icmp, 30)
-        self.assertEqual(timeouts.tcp_trans, 250)
-        self.assertEqual(timeouts.tcp_est, 7450)
-        self.assertEqual(timeouts.tcp_incoming_syn, 10)
+        self.assertEqual(timeouts.tcp_transitory, 250)
+        self.assertEqual(timeouts.tcp_established, 7450)
 
     def test_dynamic(self):
         """ NAT64 dynamic translation test """
 
     def test_dynamic(self):
         """ NAT64 dynamic translation test """
@@ -4983,7 +6151,7 @@ class TestNAT64(MethodHolder):
                                                 self.nat_addr_n)
         self.vapi.nat64_add_del_interface(self.pg0.sw_if_index)
         self.vapi.nat64_add_del_interface(self.pg1.sw_if_index, is_inside=0)
                                                 self.nat_addr_n)
         self.vapi.nat64_add_del_interface(self.pg0.sw_if_index)
         self.vapi.nat64_add_del_interface(self.pg1.sw_if_index, is_inside=0)
-        self.vapi.nat64_set_timeouts(icmp=5)
+        self.vapi.nat_set_timeouts(icmp=5, tcp_transitory=5, tcp_established=5)
 
         pkts = self.create_stream_in_ip6(self.pg0, self.pg1)
         self.pg0.add_stream(pkts)
 
         pkts = self.create_stream_in_ip6(self.pg0, self.pg1)
         self.pg0.add_stream(pkts)
@@ -4995,9 +6163,9 @@ class TestNAT64(MethodHolder):
 
         sleep(15)
 
 
         sleep(15)
 
-        # ICMP session after timeout
+        # ICMP and TCP session after timeout
         ses_num_after_timeout = self.nat64_get_ses_num()
         ses_num_after_timeout = self.nat64_get_ses_num()
-        self.assertNotEqual(ses_num_before_timeout, ses_num_after_timeout)
+        self.assertEqual(ses_num_before_timeout - ses_num_after_timeout, 2)
 
     def test_icmp_error(self):
         """ NAT64 ICMP Error message translation """
 
     def test_icmp_error(self):
         """ NAT64 ICMP Error message translation """
@@ -5005,8 +6173,6 @@ class TestNAT64(MethodHolder):
         self.udp_port_in = 6304
         self.icmp_id_in = 6305
 
         self.udp_port_in = 6304
         self.icmp_id_in = 6305
 
-        ses_num_start = self.nat64_get_ses_num()
-
         self.vapi.nat64_add_del_pool_addr_range(self.nat_addr_n,
                                                 self.nat_addr_n)
         self.vapi.nat64_add_del_interface(self.pg0.sw_if_index)
         self.vapi.nat64_add_del_pool_addr_range(self.nat_addr_n,
                                                 self.nat_addr_n)
         self.vapi.nat64_add_del_interface(self.pg0.sw_if_index)
@@ -5049,7 +6215,7 @@ class TestNAT64(MethodHolder):
                 inner = packet[IPerror]
                 self.assertEqual(inner.src, self.pg1.remote_ip4)
                 self.assertEqual(inner.dst, self.nat_addr)
                 inner = packet[IPerror]
                 self.assertEqual(inner.src, self.pg1.remote_ip4)
                 self.assertEqual(inner.dst, self.nat_addr)
-                self.check_icmp_checksum(packet)
+                self.assert_packet_checksums_valid(packet)
                 if inner.haslayer(TCPerror):
                     self.assertEqual(inner[TCPerror].dport, self.tcp_port_out)
                 elif inner.haslayer(UDPerror):
                 if inner.haslayer(TCPerror):
                     self.assertEqual(inner[TCPerror].dport, self.tcp_port_out)
                 elif inner.haslayer(UDPerror):
@@ -5078,7 +6244,7 @@ class TestNAT64(MethodHolder):
                 inner = icmp[IPerror6]
                 self.assertEqual(inner.src, self.pg0.remote_ip6)
                 self.assertEqual(inner.dst, ip.src)
                 inner = icmp[IPerror6]
                 self.assertEqual(inner.src, self.pg0.remote_ip6)
                 self.assertEqual(inner.dst, ip.src)
-                self.check_icmpv6_checksum(packet)
+                self.assert_icmpv6_checksum_valid(packet)
                 if inner.haslayer(TCPerror):
                     self.assertEqual(inner[TCPerror].sport, self.tcp_port_in)
                 elif inner.haslayer(UDPerror):
                 if inner.haslayer(TCPerror):
                     self.assertEqual(inner[TCPerror].sport, self.tcp_port_in)
                 elif inner.haslayer(UDPerror):
@@ -5140,15 +6306,14 @@ class TestNAT64(MethodHolder):
             try:
                 self.assertEqual(packet[IPv6].src, nat_addr_ip6)
                 self.assertEqual(packet[IPv6].dst, server.ip6)
             try:
                 self.assertEqual(packet[IPv6].src, nat_addr_ip6)
                 self.assertEqual(packet[IPv6].dst, server.ip6)
+                self.assert_packet_checksums_valid(packet)
                 if packet.haslayer(TCP):
                     self.assertNotEqual(packet[TCP].sport, client_tcp_in_port)
                     self.assertEqual(packet[TCP].dport, server_tcp_in_port)
                 if packet.haslayer(TCP):
                     self.assertNotEqual(packet[TCP].sport, client_tcp_in_port)
                     self.assertEqual(packet[TCP].dport, server_tcp_in_port)
-                    self.check_tcp_checksum(packet)
                     client_tcp_out_port = packet[TCP].sport
                 else:
                     self.assertNotEqual(packet[UDP].sport, client_udp_in_port)
                     self.assertEqual(packet[UDP].dport, server_udp_in_port)
                     client_tcp_out_port = packet[TCP].sport
                 else:
                     self.assertNotEqual(packet[UDP].sport, client_udp_in_port)
                     self.assertEqual(packet[UDP].dport, server_udp_in_port)
-                    self.check_udp_checksum(packet)
                     client_udp_out_port = packet[UDP].sport
             except:
                 self.logger.error(ppp("Unexpected or invalid packet:", packet))
                     client_udp_out_port = packet[UDP].sport
             except:
                 self.logger.error(ppp("Unexpected or invalid packet:", packet))
@@ -5172,14 +6337,13 @@ class TestNAT64(MethodHolder):
             try:
                 self.assertEqual(packet[IPv6].src, nat_addr_ip6)
                 self.assertEqual(packet[IPv6].dst, client.ip6)
             try:
                 self.assertEqual(packet[IPv6].src, nat_addr_ip6)
                 self.assertEqual(packet[IPv6].dst, client.ip6)
+                self.assert_packet_checksums_valid(packet)
                 if packet.haslayer(TCP):
                     self.assertEqual(packet[TCP].sport, server_tcp_out_port)
                     self.assertEqual(packet[TCP].dport, client_tcp_in_port)
                 if packet.haslayer(TCP):
                     self.assertEqual(packet[TCP].sport, server_tcp_out_port)
                     self.assertEqual(packet[TCP].dport, client_tcp_in_port)
-                    self.check_tcp_checksum(packet)
                 else:
                     self.assertEqual(packet[UDP].sport, server_udp_out_port)
                     self.assertEqual(packet[UDP].dport, client_udp_in_port)
                 else:
                     self.assertEqual(packet[UDP].sport, server_udp_out_port)
                     self.assertEqual(packet[UDP].dport, client_udp_in_port)
-                    self.check_udp_checksum(packet)
             except:
                 self.logger.error(ppp("Unexpected or invalid packet:", packet))
                 raise
             except:
                 self.logger.error(ppp("Unexpected or invalid packet:", packet))
                 raise
@@ -5203,7 +6367,7 @@ class TestNAT64(MethodHolder):
                 inner = icmp[IPerror6]
                 self.assertEqual(inner.src, server.ip6)
                 self.assertEqual(inner.dst, nat_addr_ip6)
                 inner = icmp[IPerror6]
                 self.assertEqual(inner.src, server.ip6)
                 self.assertEqual(inner.dst, nat_addr_ip6)
-                self.check_icmpv6_checksum(packet)
+                self.assert_packet_checksums_valid(packet)
                 if inner.haslayer(TCPerror):
                     self.assertEqual(inner[TCPerror].sport, server_tcp_in_port)
                     self.assertEqual(inner[TCPerror].dport,
                 if inner.haslayer(TCPerror):
                     self.assertEqual(inner[TCPerror].sport, server_tcp_in_port)
                     self.assertEqual(inner[TCPerror].dport,
@@ -5326,7 +6490,7 @@ class TestNAT64(MethodHolder):
             self.assertEqual(packet[IP].src, self.nat_addr)
             self.assertEqual(packet[IP].dst, self.pg1.remote_ip4)
             self.assertTrue(packet.haslayer(GRE))
             self.assertEqual(packet[IP].src, self.nat_addr)
             self.assertEqual(packet[IP].dst, self.pg1.remote_ip4)
             self.assertTrue(packet.haslayer(GRE))
-            self.check_ip_checksum(packet)
+            self.assert_packet_checksums_valid(packet)
         except:
             self.logger.error(ppp("Unexpected or invalid packet:", packet))
             raise
         except:
             self.logger.error(ppp("Unexpected or invalid packet:", packet))
             raise
@@ -5464,8 +6628,7 @@ class TestNAT64(MethodHolder):
             self.assertNotEqual(tcp.sport, 12345)
             external_port = tcp.sport
             self.assertEqual(tcp.dport, 80)
             self.assertNotEqual(tcp.sport, 12345)
             external_port = tcp.sport
             self.assertEqual(tcp.dport, 80)
-            self.check_tcp_checksum(p)
-            self.check_ip_checksum(p)
+            self.assert_packet_checksums_valid(p)
         except:
             self.logger.error(ppp("Unexpected or invalid packet:", p))
             raise
         except:
             self.logger.error(ppp("Unexpected or invalid packet:", p))
             raise
@@ -5486,7 +6649,7 @@ class TestNAT64(MethodHolder):
             self.assertEqual(ip.dst, self.pg3.remote_ip6)
             self.assertEqual(tcp.sport, 80)
             self.assertEqual(tcp.dport, 12345)
             self.assertEqual(ip.dst, self.pg3.remote_ip6)
             self.assertEqual(tcp.sport, 80)
             self.assertEqual(tcp.dport, 12345)
-            self.check_tcp_checksum(p)
+            self.assert_packet_checksums_valid(p)
         except:
             self.logger.error(ppp("Unexpected or invalid packet:", p))
             raise
         except:
             self.logger.error(ppp("Unexpected or invalid packet:", p))
             raise
@@ -5544,7 +6707,6 @@ class TestNAT64(MethodHolder):
     def test_reass_hairpinning(self):
         """ NAT64 fragments hairpinning """
         data = 'a' * 200
     def test_reass_hairpinning(self):
         """ NAT64 fragments hairpinning """
         data = 'a' * 200
-        client = self.pg0.remote_hosts[0]
         server = self.pg0.remote_hosts[1]
         server_in_port = random.randint(1025, 65535)
         server_out_port = random.randint(1025, 65535)
         server = self.pg0.remote_hosts[1]
         server_in_port = random.randint(1025, 65535)
         server_out_port = random.randint(1025, 65535)
@@ -5686,7 +6848,8 @@ class TestNAT64(MethodHolder):
         self.pg0.add_stream(p)
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
         self.pg0.add_stream(p)
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
-        self.pg1.get_capture(0)
+        self.pg1.assert_nothing_captured()
+        sleep(1)
         self.vapi.cli("ipfix flush")  # FIXME this should be an API call
         capture = self.pg3.get_capture(9)
         ipfix = IPFIXDecoder()
         self.vapi.cli("ipfix flush")  # FIXME this should be an API call
         capture = self.pg3.get_capture(9)
         ipfix = IPFIXDecoder()
@@ -5713,7 +6876,8 @@ class TestNAT64(MethodHolder):
         self.pg0.add_stream(p)
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
         self.pg0.add_stream(p)
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
-        self.pg1.get_capture(0)
+        self.pg1.assert_nothing_captured()
+        sleep(1)
         self.vapi.cli("ipfix flush")  # FIXME this should be an API call
         capture = self.pg3.get_capture(1)
         # verify events in data set
         self.vapi.cli("ipfix flush")  # FIXME this should be an API call
         capture = self.pg3.get_capture(1)
         # verify events in data set
@@ -5749,7 +6913,8 @@ class TestNAT64(MethodHolder):
         self.pg0.add_stream(pkts[-1])
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
         self.pg0.add_stream(pkts[-1])
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
-        self.pg1.get_capture(0)
+        self.pg1.assert_nothing_captured()
+        sleep(1)
         self.vapi.cli("ipfix flush")  # FIXME this should be an API call
         capture = self.pg3.get_capture(9)
         ipfix = IPFIXDecoder()
         self.vapi.cli("ipfix flush")  # FIXME this should be an API call
         capture = self.pg3.get_capture(9)
         ipfix = IPFIXDecoder()
@@ -5872,7 +7037,7 @@ class TestNAT64(MethodHolder):
         self.ipfix_src_port = 4739
         self.ipfix_domain_id = 1
 
         self.ipfix_src_port = 4739
         self.ipfix_domain_id = 1
 
-        self.vapi.nat64_set_timeouts()
+        self.vapi.nat_set_timeouts()
 
         interfaces = self.vapi.nat64_interface_dump()
         for intf in interfaces:
 
         interfaces = self.vapi.nat64_interface_dump()
         for intf in interfaces:
@@ -5947,6 +7112,9 @@ class TestDSlite(MethodHolder):
 
     def test_dslite(self):
         """ Test DS-Lite """
 
     def test_dslite(self):
         """ Test DS-Lite """
+        nat_config = self.vapi.nat_show_config()
+        self.assertEqual(0, nat_config.dslite_ce)
+
         self.vapi.dslite_add_del_pool_addr_range(self.nat_addr_n,
                                                  self.nat_addr_n)
         aftr_ip4 = '192.0.0.1'
         self.vapi.dslite_add_del_pool_addr_range(self.nat_addr_n,
                                                  self.nat_addr_n)
         aftr_ip4 = '192.0.0.1'
@@ -5970,7 +7138,7 @@ class TestDSlite(MethodHolder):
         self.assertEqual(capture[IP].dst, self.pg0.remote_ip4)
         self.assertNotEqual(capture[UDP].sport, 20000)
         self.assertEqual(capture[UDP].dport, 10000)
         self.assertEqual(capture[IP].dst, self.pg0.remote_ip4)
         self.assertNotEqual(capture[UDP].sport, 20000)
         self.assertEqual(capture[UDP].dport, 10000)
-        self.check_ip_checksum(capture)
+        self.assert_packet_checksums_valid(capture)
         out_port = capture[UDP].sport
 
         p = (Ether(dst=self.pg0.local_mac, src=self.pg0.remote_mac) /
         out_port = capture[UDP].sport
 
         p = (Ether(dst=self.pg0.local_mac, src=self.pg0.remote_mac) /
@@ -5987,7 +7155,7 @@ class TestDSlite(MethodHolder):
         self.assertEqual(capture[IP].dst, '192.168.1.1')
         self.assertEqual(capture[UDP].sport, 10000)
         self.assertEqual(capture[UDP].dport, 20000)
         self.assertEqual(capture[IP].dst, '192.168.1.1')
         self.assertEqual(capture[UDP].sport, 10000)
         self.assertEqual(capture[UDP].dport, 20000)
-        self.check_ip_checksum(capture)
+        self.assert_packet_checksums_valid(capture)
 
         # TCP
         p = (Ether(dst=self.pg1.local_mac, src=self.pg1.remote_mac) /
 
         # TCP
         p = (Ether(dst=self.pg1.local_mac, src=self.pg1.remote_mac) /
@@ -6004,8 +7172,7 @@ class TestDSlite(MethodHolder):
         self.assertEqual(capture[IP].dst, self.pg0.remote_ip4)
         self.assertNotEqual(capture[TCP].sport, 20001)
         self.assertEqual(capture[TCP].dport, 10001)
         self.assertEqual(capture[IP].dst, self.pg0.remote_ip4)
         self.assertNotEqual(capture[TCP].sport, 20001)
         self.assertEqual(capture[TCP].dport, 10001)
-        self.check_ip_checksum(capture)
-        self.check_tcp_checksum(capture)
+        self.assert_packet_checksums_valid(capture)
         out_port = capture[TCP].sport
 
         p = (Ether(dst=self.pg0.local_mac, src=self.pg0.remote_mac) /
         out_port = capture[TCP].sport
 
         p = (Ether(dst=self.pg0.local_mac, src=self.pg0.remote_mac) /
@@ -6022,8 +7189,7 @@ class TestDSlite(MethodHolder):
         self.assertEqual(capture[IP].dst, '192.168.1.1')
         self.assertEqual(capture[TCP].sport, 10001)
         self.assertEqual(capture[TCP].dport, 20001)
         self.assertEqual(capture[IP].dst, '192.168.1.1')
         self.assertEqual(capture[TCP].sport, 10001)
         self.assertEqual(capture[TCP].dport, 20001)
-        self.check_ip_checksum(capture)
-        self.check_tcp_checksum(capture)
+        self.assert_packet_checksums_valid(capture)
 
         # ICMP
         p = (Ether(dst=self.pg1.local_mac, src=self.pg1.remote_mac) /
 
         # ICMP
         p = (Ether(dst=self.pg1.local_mac, src=self.pg1.remote_mac) /
@@ -6039,8 +7205,7 @@ class TestDSlite(MethodHolder):
         self.assertEqual(capture[IP].src, self.nat_addr)
         self.assertEqual(capture[IP].dst, self.pg0.remote_ip4)
         self.assertNotEqual(capture[ICMP].id, 4000)
         self.assertEqual(capture[IP].src, self.nat_addr)
         self.assertEqual(capture[IP].dst, self.pg0.remote_ip4)
         self.assertNotEqual(capture[ICMP].id, 4000)
-        self.check_ip_checksum(capture)
-        self.check_icmp_checksum(capture)
+        self.assert_packet_checksums_valid(capture)
         out_id = capture[ICMP].id
 
         p = (Ether(dst=self.pg0.local_mac, src=self.pg0.remote_mac) /
         out_id = capture[ICMP].id
 
         p = (Ether(dst=self.pg0.local_mac, src=self.pg0.remote_mac) /
@@ -6056,8 +7221,7 @@ class TestDSlite(MethodHolder):
         self.assertEqual(capture[IP].src, self.pg0.remote_ip4)
         self.assertEqual(capture[IP].dst, '192.168.1.1')
         self.assertEqual(capture[ICMP].id, 4000)
         self.assertEqual(capture[IP].src, self.pg0.remote_ip4)
         self.assertEqual(capture[IP].dst, '192.168.1.1')
         self.assertEqual(capture[ICMP].id, 4000)
-        self.check_ip_checksum(capture)
-        self.check_icmp_checksum(capture)
+        self.assert_packet_checksums_valid(capture)
 
         # ping DS-Lite AFTR tunnel endpoint address
         p = (Ether(dst=self.pg1.local_mac, src=self.pg1.remote_mac) /
 
         # ping DS-Lite AFTR tunnel endpoint address
         p = (Ether(dst=self.pg1.local_mac, src=self.pg1.remote_mac) /
@@ -6111,6 +7275,9 @@ class TestDSliteCE(MethodHolder):
     def test_dslite_ce(self):
         """ Test DS-Lite CE """
 
     def test_dslite_ce(self):
         """ Test DS-Lite CE """
 
+        nat_config = self.vapi.nat_show_config()
+        self.assertEqual(1, nat_config.dslite_ce)
+
         b4_ip4 = '192.0.0.2'
         b4_ip4_n = socket.inet_pton(socket.AF_INET, b4_ip4)
         b4_ip6 = '2001:db8:62aa::375e:f4c1:1'
         b4_ip4 = '192.0.0.2'
         b4_ip4_n = socket.inet_pton(socket.AF_INET, b4_ip4)
         b4_ip6 = '2001:db8:62aa::375e:f4c1:1'
@@ -6144,7 +7311,7 @@ class TestDSliteCE(MethodHolder):
         self.assertEqual(capture[IP].dst, self.pg1.remote_ip4)
         self.assertEqual(capture[UDP].sport, 10000)
         self.assertEqual(capture[UDP].dport, 20000)
         self.assertEqual(capture[IP].dst, self.pg1.remote_ip4)
         self.assertEqual(capture[UDP].sport, 10000)
         self.assertEqual(capture[UDP].dport, 20000)
-        self.check_ip_checksum(capture)
+        self.assert_packet_checksums_valid(capture)
 
         # UDP decapsulation
         p = (Ether(dst=self.pg1.local_mac, src=self.pg1.remote_mac) /
 
         # UDP decapsulation
         p = (Ether(dst=self.pg1.local_mac, src=self.pg1.remote_mac) /
@@ -6161,7 +7328,7 @@ class TestDSliteCE(MethodHolder):
         self.assertEqual(capture[IP].dst, self.pg0.remote_ip4)
         self.assertEqual(capture[UDP].sport, 20000)
         self.assertEqual(capture[UDP].dport, 10000)
         self.assertEqual(capture[IP].dst, self.pg0.remote_ip4)
         self.assertEqual(capture[UDP].sport, 20000)
         self.assertEqual(capture[UDP].dport, 10000)
-        self.check_ip_checksum(capture)
+        self.assert_packet_checksums_valid(capture)
 
         # ping DS-Lite B4 tunnel endpoint address
         p = (Ether(dst=self.pg1.local_mac, src=self.pg1.remote_mac) /
 
         # ping DS-Lite B4 tunnel endpoint address
         p = (Ether(dst=self.pg1.local_mac, src=self.pg1.remote_mac) /
@@ -6242,12 +7409,7 @@ class TestNAT66(MethodHolder):
             try:
                 self.assertEqual(packet[IPv6].src, self.nat_addr)
                 self.assertEqual(packet[IPv6].dst, self.pg1.remote_ip6)
             try:
                 self.assertEqual(packet[IPv6].src, self.nat_addr)
                 self.assertEqual(packet[IPv6].dst, self.pg1.remote_ip6)
-                if packet.haslayer(TCP):
-                    self.check_tcp_checksum(packet)
-                elif packet.haslayer(UDP):
-                    self.check_udp_checksum(packet)
-                elif packet.haslayer(ICMPv6EchoRequest):
-                    self.check_icmpv6_checksum(packet)
+                self.assert_packet_checksums_valid(packet)
             except:
                 self.logger.error(ppp("Unexpected or invalid packet:", packet))
                 raise
             except:
                 self.logger.error(ppp("Unexpected or invalid packet:", packet))
                 raise
@@ -6278,12 +7440,7 @@ class TestNAT66(MethodHolder):
             try:
                 self.assertEqual(packet[IPv6].src, self.pg1.remote_ip6)
                 self.assertEqual(packet[IPv6].dst, self.pg0.remote_ip6)
             try:
                 self.assertEqual(packet[IPv6].src, self.pg1.remote_ip6)
                 self.assertEqual(packet[IPv6].dst, self.pg0.remote_ip6)
-                if packet.haslayer(TCP):
-                    self.check_tcp_checksum(packet)
-                elif packet.haslayer(UDP):
-                    self.check_udp_checksum(packet)
-                elif packet.haslayer(ICMPv6EchoReply):
-                    self.check_icmpv6_checksum(packet)
+                self.assert_packet_checksums_valid(packet)
             except:
                 self.logger.error(ppp("Unexpected or invalid packet:", packet))
                 raise
             except:
                 self.logger.error(ppp("Unexpected or invalid packet:", packet))
                 raise
@@ -6292,6 +7449,29 @@ class TestNAT66(MethodHolder):
         self.assertEqual(len(sm), 1)
         self.assertEqual(sm[0].total_pkts, 8)
 
         self.assertEqual(len(sm), 1)
         self.assertEqual(sm[0].total_pkts, 8)
 
+    def test_check_no_translate(self):
+        """ NAT66 translate only when egress interface is outside interface """
+        self.vapi.nat66_add_del_interface(self.pg0.sw_if_index)
+        self.vapi.nat66_add_del_interface(self.pg1.sw_if_index)
+        self.vapi.nat66_add_del_static_mapping(self.pg0.remote_ip6n,
+                                               self.nat_addr_n)
+
+        # in2out
+        p = (Ether(dst=self.pg0.local_mac, src=self.pg0.remote_mac) /
+             IPv6(src=self.pg0.remote_ip6, dst=self.pg1.remote_ip6) /
+             UDP())
+        self.pg0.add_stream([p])
+        self.pg_enable_capture(self.pg_interfaces)
+        self.pg_start()
+        capture = self.pg1.get_capture(1)
+        packet = capture[0]
+        try:
+            self.assertEqual(packet[IPv6].src, self.pg0.remote_ip6)
+            self.assertEqual(packet[IPv6].dst, self.pg1.remote_ip6)
+        except:
+            self.logger.error(ppp("Unexpected or invalid packet:", packet))
+            raise
+
     def clear_nat66(self):
         """
         Clear NAT66 configuration.
     def clear_nat66(self):
         """
         Clear NAT66 configuration.
@@ -6316,5 +7496,6 @@ class TestNAT66(MethodHolder):
             self.logger.info(self.vapi.cli("show nat66 static mappings"))
             self.clear_nat66()
 
             self.logger.info(self.vapi.cli("show nat66 static mappings"))
             self.clear_nat66()
 
+
 if __name__ == '__main__':
     unittest.main(testRunner=VppTestRunner)
 if __name__ == '__main__':
     unittest.main(testRunner=VppTestRunner)