NAT44: nat44_del_session and nat44_user_session_details API update (VPP-1271)
[vpp.git] / test / test_nat.py
index 34726ea..e2f3465 100644 (file)
@@ -7,7 +7,6 @@ import StringIO
 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.inet6 import IPv6, ICMPv6EchoRequest, ICMPv6EchoReply
@@ -26,114 +25,6 @@ from util import mactobinary
 class MethodHolder(VppTestCase):
     """ NAT create capture and verify method holder """
 
-    @classmethod
-    def setUpClass(cls):
-        super(MethodHolder, cls).setUpClass()
-
-    def tearDown(self):
-        super(MethodHolder, self).tearDown()
-
-    def check_ip_checksum(self, pkt):
-        """
-        Check IP checksum of the packet
-
-        :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)
-
-    def check_tcp_checksum(self, pkt):
-        """
-        Check TCP checksum in IP packet
-
-        :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)
-
-    def check_udp_checksum(self, pkt):
-        """
-        Check UDP checksum in IP packet
-
-        :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)
-
-    def check_icmp_errror_embedded(self, pkt):
-        """
-        Check ICMP error embeded packet checksum
-
-        :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):
-        """
-        Check ICMP checksum in IPv4 packet
-
-        :param pkt: Packet to check ICMP checksum
-        """
-        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):
-        """
-        Check ICMPv6 checksum in IPv4 packet
-
-        :param pkt: Packet to check ICMPv6 checksum
-        """
-        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)
-
     def create_stream_in(self, in_if, out_if, dst_ip=None, ttl=64):
         """
         Create packet stream for inside network
@@ -383,7 +274,7 @@ class MethodHolder(VppTestCase):
         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)
@@ -394,7 +285,7 @@ class MethodHolder(VppTestCase):
                         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)
@@ -408,10 +299,7 @@ class MethodHolder(VppTestCase):
                     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))
@@ -442,16 +330,14 @@ class MethodHolder(VppTestCase):
         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.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)
-                    self.check_icmp_checksum(packet)
             except:
                 self.logger.error(ppp("Unexpected or invalid packet "
                                       "(inside network):", packet))
@@ -471,16 +357,14 @@ class MethodHolder(VppTestCase):
             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)
-                    self.check_tcp_checksum(packet)
                 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)
-                    self.check_icmpv6_checksum(packet)
             except:
                 self.logger.error(ppp("Unexpected or invalid packet "
                                       "(inside network):", packet))
@@ -655,7 +539,7 @@ class MethodHolder(VppTestCase):
         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)
@@ -663,7 +547,7 @@ class MethodHolder(VppTestCase):
                 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
@@ -688,11 +572,55 @@ class MethodHolder(VppTestCase):
                   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()))
+        self.assert_packet_checksums_valid(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
@@ -910,6 +838,7 @@ 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.tcp_external_port = 80
 
             cls.create_pg_interfaces(range(10))
             cls.interfaces = list(cls.pg_interfaces[0:4])
@@ -922,6 +851,9 @@ class TestNAT44(MethodHolder):
             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)
@@ -1029,8 +961,10 @@ class TestNAT44(MethodHolder):
                 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)
 
         lb_static_mappings = self.vapi.nat44_lb_static_mapping_dump()
@@ -1041,6 +975,7 @@ class TestNAT44(MethodHolder):
                 lb_sm.protocol,
                 vrf_id=lb_sm.vrf_id,
                 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,
@@ -1071,7 +1006,8 @@ class TestNAT44(MethodHolder):
     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=""):
+                                 proto=0, twice_nat=0, self_twice_nat=0,
+                                 out2in_only=0, tag=""):
         """
         Add/delete NAT44 static mapping
 
@@ -1084,6 +1020,9 @@ class TestNAT44(MethodHolder):
         :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
         """
@@ -1102,6 +1041,7 @@ class TestNAT44(MethodHolder):
             vrf_id,
             proto,
             twice_nat,
+            self_twice_nat,
             out2in_only,
             tag,
             is_add)
@@ -1362,6 +1302,19 @@ class TestNAT44(MethodHolder):
             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,
@@ -1533,14 +1486,12 @@ class TestNAT44(MethodHolder):
         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)
+            self.assert_packet_checksums_valid(p)
         except:
             self.logger.error(ppp("Unexpected or invalid packet:", p))
             raise
@@ -1577,8 +1528,7 @@ class TestNAT44(MethodHolder):
             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)
+            self.assert_packet_checksums_valid(p)
         except:
             self.logger.error(ppp("Unexpected or invalid packet:", p))
             raise
@@ -1610,14 +1560,12 @@ class TestNAT44(MethodHolder):
         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)
+            self.assert_packet_checksums_valid(p)
         except:
             self.logger.error(ppp("Unexpected or invalid packet:", p))
             raise
@@ -1636,8 +1584,7 @@ class TestNAT44(MethodHolder):
             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)
+            self.assert_packet_checksums_valid(p)
         except:
             self.logger.error(ppp("Unexpected or invalid packet:", p))
             raise
@@ -1730,8 +1677,7 @@ class TestNAT44(MethodHolder):
             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.assert_packet_checksums_valid(p)
         except:
             self.logger.error(ppp("Unexpected or invalid packet:", p))
             raise
@@ -1780,8 +1726,7 @@ class TestNAT44(MethodHolder):
             else:
                 server = server2
             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
@@ -1800,16 +1745,53 @@ class TestNAT44(MethodHolder):
             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)
+            self.assert_packet_checksums_valid(p)
         except:
             self.logger.error(ppp("Unexpected or invalid packet:", p))
             raise
 
-        # multiple clients
+        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},
+                  {'addr': server2.ip4n,
+                   'port': local_port,
+                   'probability': 10}]
+
+        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, 20)
+        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) /
@@ -1872,8 +1854,7 @@ class TestNAT44(MethodHolder):
             else:
                 server = server2
             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
@@ -1892,8 +1873,7 @@ class TestNAT44(MethodHolder):
             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)
+            self.assert_packet_checksums_valid(p)
         except:
             self.logger.error(ppp("Unexpected or invalid packet:", p))
             raise
@@ -1913,8 +1893,7 @@ class TestNAT44(MethodHolder):
             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)
+            self.assert_packet_checksums_valid(p)
         except:
             self.logger.error(ppp("Unexpected or invalid packet:", p))
             raise
@@ -1933,8 +1912,7 @@ class TestNAT44(MethodHolder):
             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)
+            self.assert_packet_checksums_valid(p)
         except:
             self.logger.error(ppp("Unexpected or invalid packet:", p))
             raise
@@ -2120,6 +2098,7 @@ class TestNAT44(MethodHolder):
                 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)
@@ -2179,7 +2158,7 @@ class TestNAT44(MethodHolder):
             self.assertEqual(ip.dst, server.ip4)
             self.assertNotEqual(tcp.sport, host_in_port)
             self.assertEqual(tcp.dport, server_in_port)
-            self.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))
@@ -2201,7 +2180,7 @@ class TestNAT44(MethodHolder):
             self.assertEqual(ip.dst, host.ip4)
             self.assertEqual(tcp.sport, server_out_port)
             self.assertEqual(tcp.dport, host_in_port)
-            self.check_tcp_checksum(p)
+            self.assert_packet_checksums_valid(p)
         except:
             self.logger.error(ppp("Unexpected or invalid packet:", p))
             raise
@@ -2252,7 +2231,7 @@ 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.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)
@@ -2289,7 +2268,7 @@ class TestNAT44(MethodHolder):
                 if packet.haslayer(TCP):
                     self.assertEqual(packet[TCP].dport, self.tcp_port_in)
                     self.assertEqual(packet[TCP].sport, server_tcp_port)
-                    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)
@@ -2325,7 +2304,7 @@ 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.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)
@@ -2362,7 +2341,7 @@ class TestNAT44(MethodHolder):
                 if packet.haslayer(TCP):
                     self.assertEqual(packet[TCP].dport, self.tcp_port_in)
                     self.assertEqual(packet[TCP].sport, server_tcp_port)
-                    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)
@@ -2398,6 +2377,31 @@ class TestNAT44(MethodHolder):
         # 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)
@@ -2437,15 +2441,44 @@ class TestNAT44(MethodHolder):
         # 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()
+        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):
@@ -2468,17 +2501,23 @@ class TestNAT44(MethodHolder):
         # 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()
-        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 """
@@ -2920,7 +2959,7 @@ class TestNAT44(MethodHolder):
             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)
+            self.assert_packet_checksums_valid(packet)
         except:
             self.logger.error(ppp("Unexpected or invalid packet:", packet))
             raise
@@ -2940,7 +2979,7 @@ 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.check_ip_checksum(packet)
+            self.assert_packet_checksums_valid(packet)
         except:
             self.logger.error(ppp("Unexpected or invalid packet:", packet))
             raise
@@ -2975,7 +3014,7 @@ class TestNAT44(MethodHolder):
             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)
+            self.assert_packet_checksums_valid(packet)
         except:
             self.logger.error(ppp("Unexpected or invalid packet:", packet))
             raise
@@ -2995,7 +3034,7 @@ class TestNAT44(MethodHolder):
             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
@@ -3030,7 +3069,7 @@ 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.check_ip_checksum(packet)
+            self.assert_packet_checksums_valid(packet)
         except:
             self.logger.error(ppp("Unexpected or invalid packet:", packet))
             raise
@@ -3050,7 +3089,7 @@ 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.check_ip_checksum(packet)
+            self.assert_packet_checksums_valid(packet)
         except:
             self.logger.error(ppp("Unexpected or invalid packet:", packet))
             raise
@@ -3060,8 +3099,6 @@ class TestNAT44(MethodHolder):
         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"
 
@@ -3096,7 +3133,7 @@ class TestNAT44(MethodHolder):
             self.assertEqual(packet[IP].src, self.nat_addr)
             self.assertEqual(packet[IP].dst, server.ip4)
             self.assertTrue(packet.haslayer(GRE))
-            self.check_ip_checksum(packet)
+            self.assert_packet_checksums_valid(packet)
         except:
             self.logger.error(ppp("Unexpected or invalid packet:", packet))
             raise
@@ -3116,7 +3153,7 @@ class TestNAT44(MethodHolder):
             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
@@ -3243,7 +3280,7 @@ class TestNAT44(MethodHolder):
             self.assertEqual(ip.dst, server.ip4)
             self.assertNotEqual(tcp.sport, host_in_port)
             self.assertEqual(tcp.dport, server_in_port)
-            self.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))
@@ -3265,151 +3302,321 @@ class TestNAT44(MethodHolder):
             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)
-        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.check_tcp_checksum(p)
-            self.check_ip_checksum(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.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
 
-    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]
+    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
-        eh_port_in = 0
 
         self.vapi.nat44_forwarding_enable_disable(1)
-        self.nat44_add_address(self.nat_addr, twice_nat=1)
-        self.nat44_add_static_mapping(local_host.ip4, self.nat_addr,
+        self.nat44_add_address(self.nat_addr)
+        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,
-                                      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,
+                                      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)
 
         # from client to service
-        p = (Ether(src=self.pg9.remote_mac, dst=self.pg9.local_mac) /
-             IP(src=remote_host.ip4, dst=self.nat_addr) /
+        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.pg9.add_stream(p)
+        self.pg1.add_stream(p)
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
-        capture = self.pg9.get_capture(1)
+        capture = self.pg0.get_capture(1)
         p = capture[0]
-        server = None
         try:
             ip = p[IP]
             tcp = p[TCP]
-            self.assertEqual(ip.dst, local_host.ip4)
-            self.assertEqual(ip.src, self.nat_addr)
+            self.assertEqual(ip.dst, self.pg0.remote_ip4)
             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
-        p = (Ether(src=self.pg9.remote_mac, dst=self.pg9.local_mac) /
-             IP(src=local_host.ip4, dst=self.nat_addr) /
-             TCP(sport=local_port, dport=eh_port_in))
-        self.pg9.add_stream(p)
+        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.pg9.get_capture(1)
+        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(ip.dst, remote_host.ip4)
+            self.assertEqual(ip.src, external_addr)
             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
 
-    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)
-
+        # 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()
+        capture = self.pg1.get_capture(len(pkts))
+        self.verify_capture_out(capture)
         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)
 
-        sessions = self.vapi.nat44_user_session_dump(self.pg0.remote_ip4n, 0)
-        nsessions = len(sessions)
+        # 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.verify_capture_in(capture, self.pg0)
 
-        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,
+    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)
+
+        # 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()
+        capture = self.pg1.get_capture(len(pkts))
+        self.verify_capture_out(capture)
+
+        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)
+
+        # session initiaded from remote host - do not translate
+        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()
+        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)
+
+    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_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)
+
+        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()
+        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, 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
+
+        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)
+        p = capture[0]
+        try:
+            ip = p[IP]
+            tcp = p[TCP]
+            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
+
+    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_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]
+        external_port = 80
+        local_port = 8080
+        eh_port_in = 0
+
+        self.vapi.nat44_forwarding_enable_disable(1)
+        self.nat44_add_address(self.nat_addr, twice_nat=1)
+        self.nat44_add_static_mapping(local_host.ip4, self.nat_addr,
+                                      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,
+                                                  is_inside=0)
+
+        # from client to service
+        p = (Ether(src=self.pg9.remote_mac, dst=self.pg9.local_mac) /
+             IP(src=remote_host.ip4, dst=self.nat_addr) /
+             TCP(sport=12345, 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.dst, local_host.ip4)
+            self.assertEqual(ip.src, self.nat_addr)
+            self.assertEqual(tcp.dport, local_port)
+            self.assertNotEqual(tcp.sport, 12345)
+            eh_port_in = tcp.sport
+            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.pg9.remote_mac, dst=self.pg9.local_mac) /
+             IP(src=local_host.ip4, dst=self.nat_addr) /
+             TCP(sport=local_port, dport=eh_port_in))
+        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.assertEqual(tcp.sport, external_port)
+            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()
+        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)
@@ -3489,10 +3696,8 @@ class TestNAT44(MethodHolder):
 
     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
@@ -3595,215 +3800,423 @@ class TestNAT44(MethodHolder):
             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.assert_packet_checksums_valid(p)
         except:
             self.logger.error(ppp("Unexpected or invalid packet:", p))
             raise
 
-    def test_twice_nat(self):
-        """ Twice NAT44 """
+    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
-        eh_port_in = 0
+
+        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)
-        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,
+        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},
+                      {'addr': server2.ip4n,
+                       'port': port_in2,
+                       'probability': 50}]
+            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)
 
-        p = (Ether(src=self.pg1.remote_mac, dst=self.pg1.local_mac) /
-             IP(src=self.pg1.remote_ip4, dst=self.nat_addr) /
+        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))
-        self.pg1.add_stream(p)
+        pg1.add_stream(p)
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
-        capture = self.pg0.get_capture(1)
+        capture = 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)
+            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
-            self.check_tcp_checksum(p)
-            self.check_ip_checksum(p)
+            saved_port_in = tcp.dport
+            self.assert_packet_checksums_valid(p)
         except:
             self.logger.error(ppp("Unexpected or invalid packet:", p))
             raise
 
-        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))
-        self.pg0.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()
-        capture = self.pg1.get_capture(1)
+        capture = 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.dst, client.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.assert_packet_checksums_valid(p)
         except:
             self.logger.error(ppp("Unexpected or invalid packet:", p))
             raise
 
+        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 """
-        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]
+        self.twice_nat_common(lb=True)
 
-        locals = [{'addr': server1.ip4n,
-                   'port': local_port,
-                   'probability': 50},
-                  {'addr': server2.ip4n,
-                   'port': local_port,
-                   'probability': 50}]
+    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)
 
-        self.nat44_add_address(self.nat_addr)
-        self.nat44_add_address(twice_nat_addr, twice_nat=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)
 
-        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)
+    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)
+
+        # 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.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)
+
+        # remove interface address and check NAT address pool
+        self.pg7.unconfig_ip4()
+        adresses = self.vapi.nat44_address_dump()
+        self.assertEqual(0, len(adresses))
+
+    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)
 
-        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)
+        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()
-        capture = self.pg0.get_capture(1)
-        p = capture[0]
-        server = None
+        frags = self.pg1.get_capture(0)
+        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_tcp_session_close_in(self):
+        """ Close TCP session from inside network """
+        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)
+
+        sessions = self.vapi.nat44_user_session_dump(self.pg0.remote_ip4n, 0)
+        start_sessnum = len(sessions)
+
+        self.initiate_tcp_session(self.pg0, self.pg1)
+
+        # close the session from inside
         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(tcp.dport, local_port)
-            self.check_tcp_checksum(p)
-            self.check_ip_checksum(p)
+            # 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)
+
+            self.initiate_tcp_session(self.pg0, self.pg1)
+            sessions = self.vapi.nat44_user_session_dump(self.pg0.remote_ip4n,
+                                                         0)
+            self.assertEqual(len(sessions) - start_sessnum, 1)
         except:
-            self.logger.error(ppp("Unexpected or invalid packet:", p))
+            self.logger.error("TCP session termination failed")
             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)
-        self.pg_enable_capture(self.pg_interfaces)
-        self.pg_start()
-        capture = self.pg1.get_capture(1)
-        p = capture[0]
+    def test_tcp_session_close_out(self):
+        """ Close TCP session from outside network """
+        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)
+
+        sessions = self.vapi.nat44_user_session_dump(self.pg0.remote_ip4n, 0)
+        start_sessnum = len(sessions)
+
+        self.initiate_tcp_session(self.pg0, self.pg1)
+
+        # close the session from outside
         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)
-        except:
-            self.logger.error(ppp("Unexpected or invalid packet:", p))
-            raise
+            # 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)
 
-    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)
+            # 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))
 
-        # no address in NAT pool
-        adresses = self.vapi.nat44_address_dump()
-        self.assertEqual(0, len(adresses))
+            self.pg0.add_stream(p)
+            self.pg_enable_capture(self.pg_interfaces)
+            self.pg_start()
+            self.pg1.get_capture(1)
 
-        # 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)
+            # 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)
 
-        # remove interface address and check NAT address pool
-        self.pg7.unconfig_ip4()
-        adresses = self.vapi.nat44_address_dump()
-        self.assertEqual(0, len(adresses))
+            self.initiate_tcp_session(self.pg0, self.pg1)
+            sessions = self.vapi.nat44_user_session_dump(self.pg0.remote_ip4n,
+                                                         0)
+            self.assertEqual(len(sessions) - start_sessnum, 1)
+        except:
+            self.logger.error("TCP session termination failed")
+            raise
 
-    def test_ipfix_max_frags(self):
-        """ IPFIX logging maximum fragments pending reassembly exceeded """
+    def test_tcp_session_close_simultaneous(self):
+        """ Close TCP session from inside network """
         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()
-        frags = self.pg1.get_capture(0)
-        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)
+        sessions = self.vapi.nat44_user_session_dump(self.pg0.remote_ip4n, 0)
+        start_sessnum = len(sessions)
+
+        self.initiate_tcp_session(self.pg0, self.pg1)
+
+        # close the session from inside
+        try:
+            # 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)
+
+            # 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.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)
+
+            self.initiate_tcp_session(self.pg0, self.pg1)
+            sessions = self.vapi.nat44_user_session_dump(self.pg0.remote_ip4n,
+                                                         0)
+            self.assertEqual(len(sessions) - start_sessnum, 1)
+        except:
+            self.logger.error("TCP session termination failed")
+            raise
 
     def tearDown(self):
         super(TestNAT44, self).tearDown()
@@ -4056,50 +4469,6 @@ class TestDeterministicNAT(MethodHolder):
                                       "(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
@@ -4906,8 +5275,6 @@ class TestNAT64(MethodHolder):
         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)
@@ -4950,7 +5317,7 @@ class TestNAT64(MethodHolder):
                 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):
@@ -4979,7 +5346,7 @@ class TestNAT64(MethodHolder):
                 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):
@@ -5041,15 +5408,14 @@ class TestNAT64(MethodHolder):
             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)
-                    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)
-                    self.check_udp_checksum(packet)
                     client_udp_out_port = packet[UDP].sport
             except:
                 self.logger.error(ppp("Unexpected or invalid packet:", packet))
@@ -5073,14 +5439,13 @@ class TestNAT64(MethodHolder):
             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)
-                    self.check_tcp_checksum(packet)
                 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
@@ -5104,7 +5469,7 @@ class TestNAT64(MethodHolder):
                 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,
@@ -5227,7 +5592,7 @@ 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.check_ip_checksum(packet)
+            self.assert_packet_checksums_valid(packet)
         except:
             self.logger.error(ppp("Unexpected or invalid packet:", packet))
             raise
@@ -5365,8 +5730,7 @@ class TestNAT64(MethodHolder):
             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
@@ -5387,7 +5751,7 @@ class TestNAT64(MethodHolder):
             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
@@ -5445,7 +5809,6 @@ class TestNAT64(MethodHolder):
     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)
@@ -5871,7 +6234,7 @@ 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.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) /
@@ -5888,7 +6251,7 @@ 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.check_ip_checksum(capture)
+        self.assert_packet_checksums_valid(capture)
 
         # TCP
         p = (Ether(dst=self.pg1.local_mac, src=self.pg1.remote_mac) /
@@ -5905,8 +6268,7 @@ 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.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) /
@@ -5923,8 +6285,7 @@ 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.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) /
@@ -5940,8 +6301,7 @@ 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.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) /
@@ -5957,8 +6317,7 @@ 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.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) /
@@ -6045,7 +6404,7 @@ 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.check_ip_checksum(capture)
+        self.assert_packet_checksums_valid(capture)
 
         # UDP decapsulation
         p = (Ether(dst=self.pg1.local_mac, src=self.pg1.remote_mac) /
@@ -6062,7 +6421,7 @@ 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.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) /
@@ -6086,5 +6445,150 @@ class TestDSliteCE(MethodHolder):
             self.logger.info(
                 self.vapi.cli("show dslite b4-tunnel-endpoint-address"))
 
+
+class TestNAT66(MethodHolder):
+    """ NAT66 Test Cases """
+
+    @classmethod
+    def setUpClass(cls):
+        super(TestNAT66, cls).setUpClass()
+
+        try:
+            cls.nat_addr = 'fd01:ff::2'
+            cls.nat_addr_n = socket.inet_pton(socket.AF_INET6, cls.nat_addr)
+
+            cls.create_pg_interfaces(range(2))
+            cls.interfaces = list(cls.pg_interfaces)
+
+            for i in cls.interfaces:
+                i.admin_up()
+                i.config_ip6()
+                i.configure_ipv6_neighbors()
+
+        except Exception:
+            super(TestNAT66, cls).tearDownClass()
+            raise
+
+    def test_static(self):
+        """ 1:1 NAT66 test """
+        self.vapi.nat66_add_del_interface(self.pg0.sw_if_index)
+        self.vapi.nat66_add_del_interface(self.pg1.sw_if_index, is_inside=0)
+        self.vapi.nat66_add_del_static_mapping(self.pg0.remote_ip6n,
+                                               self.nat_addr_n)
+
+        # in2out
+        pkts = []
+        p = (Ether(dst=self.pg0.local_mac, src=self.pg0.remote_mac) /
+             IPv6(src=self.pg0.remote_ip6, dst=self.pg1.remote_ip6) /
+             TCP())
+        pkts.append(p)
+        p = (Ether(dst=self.pg0.local_mac, src=self.pg0.remote_mac) /
+             IPv6(src=self.pg0.remote_ip6, dst=self.pg1.remote_ip6) /
+             UDP())
+        pkts.append(p)
+        p = (Ether(dst=self.pg0.local_mac, src=self.pg0.remote_mac) /
+             IPv6(src=self.pg0.remote_ip6, dst=self.pg1.remote_ip6) /
+             ICMPv6EchoRequest())
+        pkts.append(p)
+        p = (Ether(dst=self.pg0.local_mac, src=self.pg0.remote_mac) /
+             IPv6(src=self.pg0.remote_ip6, dst=self.pg1.remote_ip6) /
+             GRE() / IP() / TCP())
+        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))
+        for packet in capture:
+            try:
+                self.assertEqual(packet[IPv6].src, self.nat_addr)
+                self.assertEqual(packet[IPv6].dst, self.pg1.remote_ip6)
+                self.assert_packet_checksums_valid(packet)
+            except:
+                self.logger.error(ppp("Unexpected or invalid packet:", packet))
+                raise
+
+        # out2in
+        pkts = []
+        p = (Ether(dst=self.pg1.local_mac, src=self.pg1.remote_mac) /
+             IPv6(src=self.pg1.remote_ip6, dst=self.nat_addr) /
+             TCP())
+        pkts.append(p)
+        p = (Ether(dst=self.pg1.local_mac, src=self.pg1.remote_mac) /
+             IPv6(src=self.pg1.remote_ip6, dst=self.nat_addr) /
+             UDP())
+        pkts.append(p)
+        p = (Ether(dst=self.pg1.local_mac, src=self.pg1.remote_mac) /
+             IPv6(src=self.pg1.remote_ip6, dst=self.nat_addr) /
+             ICMPv6EchoReply())
+        pkts.append(p)
+        p = (Ether(dst=self.pg1.local_mac, src=self.pg1.remote_mac) /
+             IPv6(src=self.pg1.remote_ip6, dst=self.nat_addr) /
+             GRE() / IP() / TCP())
+        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 packet in capture:
+            try:
+                self.assertEqual(packet[IPv6].src, self.pg1.remote_ip6)
+                self.assertEqual(packet[IPv6].dst, self.pg0.remote_ip6)
+                self.assert_packet_checksums_valid(packet)
+            except:
+                self.logger.error(ppp("Unexpected or invalid packet:", packet))
+                raise
+
+        sm = self.vapi.nat66_static_mapping_dump()
+        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.
+        """
+        interfaces = self.vapi.nat66_interface_dump()
+        for intf in interfaces:
+            self.vapi.nat66_add_del_interface(intf.sw_if_index,
+                                              intf.is_inside,
+                                              is_add=0)
+
+        static_mappings = self.vapi.nat66_static_mapping_dump()
+        for sm in static_mappings:
+            self.vapi.nat66_add_del_static_mapping(sm.local_ip_address,
+                                                   sm.external_ip_address,
+                                                   sm.vrf_id,
+                                                   is_add=0)
+
+    def tearDown(self):
+        super(TestNAT66, self).tearDown()
+        if not self.vpp_dead:
+            self.logger.info(self.vapi.cli("show nat66 interfaces"))
+            self.logger.info(self.vapi.cli("show nat66 static mappings"))
+            self.clear_nat66()
+
+
 if __name__ == '__main__':
     unittest.main(testRunner=VppTestRunner)