Merge branch 'nat-nftables' of github.com:c-po/vyos-1x into current

* 'nat-nftables' of github.com:c-po/vyos-1x: (27 commits)
  nat: T2198: remove "tcp_udp" from "show nat dest stat"x
  Debian: add required dependency on systemd
  nat: T2198: add common ip-protocol validator
  nat: T2198: use Jinja2 macro for common ruleset for SNAT and DNAT
  nat: T2198: restructure DNAT template part for less duplicated code
  nat: T2198: add support for SNAT based on source addresses
  nat: T2198: set default protocol to all to be backwards compatible
  nat: T2198: sync generated SNAT rules with VyOS 1.2
  nat: T2198: sync generated DNAT rules with VyOS 1.2
  nat: T2198: do not run DNAT rule if rule is disabled
  nat: T2198: restructure DNAT template
  nat: T2198: verify translation address for SNAT and DNAT
  nat: T2198: extend verify() for destination ports
  nat: T2198: migrate "log enable" node to only "log"
  nat: T2198: add protocol completion helper and regex constraint
  nat: T2198: migrate "show nat" commands to XML and Python
  nat: T2198: add some basic verify() rules
  nat: T2198: split nat-address-port include into individual files
  nat: T2198: add ipv4-{address,prefix,rage}-exclude validators
  nat: T2198: add new ipv4-range validator
  ...

17 files changed, 1469 insertions, 0 deletions

diff --git a/data/templates/firewall/nftables-nat.tmpl b/data/templates/firewall/nftables-nat.tmpl
new file mode 100644
index 000000000..abb32ddc6
--- /dev/null
+++ b/data/templates/firewall/nftables-nat.tmpl
@@ -0,0 +1,139 @@
+#!/usr/sbin/nft -f
+
+# Start with clean NAT table
+flush table nat
+
+{% if helper_functions == 'remove' %}
+{# NAT if going to be disabled - remove rules and targets from nftables #}
+
+{% set base_command = "delete rule ip raw" %}
+{{ base_command }} PREROUTING handle {{ pre_ct_ignore }}
+{{ base_command }} OUTPUT     handle {{ out_ct_ignore }}
+{{ base_command }} PREROUTING handle {{ pre_ct_conntrack }}
+{{ base_command }} OUTPUT     handle {{ out_ct_conntrack }}
+
+delete chain ip raw NAT_CONNTRACK
+
+{% elif helper_functions == 'add' %}
+{# NAT if enabled - add targets to nftables #}
+add chain ip raw NAT_CONNTRACK
+add rule ip raw NAT_CONNTRACK counter accept
+
+{% set base_command = "add rule ip raw" %}
+
+{{ base_command }} PREROUTING position {{ pre_ct_ignore }}    counter jump VYATTA_CT_HELPER
+{{ base_command }} OUTPUT     position {{ out_ct_ignore }}    counter jump VYATTA_CT_HELPER
+{{ base_command }} PREROUTING position {{ pre_ct_conntrack }} counter jump NAT_CONNTRACK
+{{ base_command }} OUTPUT     position {{ out_ct_conntrack }} counter jump NAT_CONNTRACK
+{% endif %}
+
+{% macro nat_rule(rule, chain) %}
+{%   set src_addr  = "ip saddr " + rule.source_address if rule.source_address %}
+{%   set src_port  = "sport { " + rule.source_port +" }" if rule.source_port %}
+{%   set dst_addr  = "ip daddr " + rule.dest_address if rule.dest_address %}
+{%   set dst_port  = "dport { " + rule.dest_port +" }" if rule.dest_port %}
+{%   set comment   = "DST-NAT-" + rule.number %}
+
+{%   if chain == "PREROUTING" %}
+{%     set interface = " iifname \"" + rule.interface_in + "\"" %}
+{%     set trns_addr = "dnat to " + rule.translation_address %}
+{%   elif chain == "POSTROUTING" %}
+{%     set interface = " oifname \"" + rule.interface_out + "\"" %}
+{%     set trns_addr = rule.translation_address %}
+{%     if rule.translation_address != 'masquerade' %}
+{%       set trns_addr = "snat to " + trns_addr %}
+{%     endif %}
+{%   endif %}
+{%   set trns_port = ":" + rule.translation_port if rule.translation_port %}
+
+{%   if rule.protocol == "tcp_udp" %}
+{%     set protocol  = "tcp" %}
+{%     set comment   = comment + " tcp_udp" %}
+{%   else %}
+{%     set protocol  = rule.protocol %}
+{%   endif %}
+
+{%   if rule.log %}
+{%     set base_log = "[NAT-DST-" + rule.number %}
+{%     if rule.exclude %}
+{%       set log = base_log + "-EXCL]" %}
+{%     elif rule.translation_address == 'masquerade' %}
+{%       set log = base_log + "-MASQ]" %}
+{%     else %}
+{%       set log = base_log + "]" %}
+{%     endif %}
+{%   endif %}
+
+{%   if rule.exclude %}
+{#     rule has been marked as "exclude" thus we simply return here #}
+{%     set trns_addr = "return" %}
+{%     set trns_port = "" %}
+{%   endif %}
+
+{%   set output = "add rule ip nat " + chain + interface %}
+
+{%   if protocol != "all" %}
+{%     set output = output + " ip protocol " + protocol %}
+{%   endif %}
+
+{%   if src_addr %}
+{%     set output = output + " " + src_addr %}
+{%   endif %}
+{%   if src_port %}
+{%     set output = output + " " + protocol + " " + src_port %}
+{%   endif %}
+
+{%   if dst_addr %}
+{%     set output = output + " " + dst_addr %}
+{%   endif %}
+{%   if dst_port %}
+{%     set output = output + " " + protocol + " " + dst_port %}
+{%   endif %}
+
+{#   Count packets #}
+{%     set output = output + " counter" %}
+
+{#   Special handling of log option, we must repeat the entire rule before the #}
+{#   NAT translation options are added, this is essential                      #}
+{%   if log %}
+{%     set log_output = output + " log prefix \"" + log + "\" comment \"" + comment + "\"" %}
+{%   endif %}
+
+{%   if trns_addr %}
+{%     set output = output + " " + trns_addr %}
+{%   endif %}
+
+{%   if trns_port %}
+{#     Do not add a whitespace here, translation port must be directly added after IP address #}
+{#     e.g. 192.0.2.10:3389                                                                   #}
+{%     set output = output + trns_port %}
+{%   endif %}
+
+{%   if comment %}
+{%     set output = output + " comment \"" + comment + "\"" %}
+{%   endif %}
+
+{{ log_output if log_output }}
+{{ output }}
+
+{#   Special handling if protocol is tcp_udp, we must repeat the entire rule with udp as protocol #}
+{%   if rule.protocol == "tcp_udp" %}
+{#     Beware of trailing whitespace, without it the comment tcp_udp will be changed to udp_udp   #}
+{{ log_output | replace("tcp ", "udp ") if log_output }}
+{{ output | replace("tcp ", "udp ") }}
+{%   endif %}
+{% endmacro %}
+
+#
+# Destination NAT rules build up here
+#
+{% for rule in destination if not rule.disabled -%}
+{{ nat_rule(rule, 'PREROUTING') }}
+{% endfor %}
+
+#
+# Source NAT rules build up here
+#
+{% for rule in source if not rule.disabled -%}
+{{ nat_rule(rule, 'POSTROUTING') }}
+{% endfor %}
diff --git a/debian/control b/debian/control
index ab0fc0b29..bd6e445ee 100644
--- a/debian/control
+++ b/debian/control
@@ -32,7 +32,9 @@ Depends: python3,
   python3-waitress,
   python3-netaddr,
   python3-zmq,
+  python3-jmespath,
   cron,
+  systemd,
   easy-rsa,
   ipaddrcheck,
   tcpdump,
@@ -90,8 +92,11 @@ Depends: python3,
   pmacct (>= 1.6.0),
   python3-certbot-nginx,
   pppoe,
+  libxml-simple-perl,
   salt-minion,
   vyos-utils,
+  nftables (>= 0.9.3),
+  conntrack,
   ${shlibs:Depends},
   ${misc:Depends}
 Description: VyOS configuration scripts and data
diff --git a/interface-definitions/include/nat-address.xml.i b/interface-definitions/include/nat-address.xml.i
new file mode 100644
index 000000000..933dae07b
--- /dev/null
+++ b/interface-definitions/include/nat-address.xml.i
@@ -0,0 +1,37 @@
+<leafNode name="address">
+  <properties>
+    <help>IP address, subnet, or range</help>
+    <valueHelp>
+      <format>ipv4</format>
+      <description>IPv4 address to match</description>
+    </valueHelp>
+    <valueHelp>
+      <format>ipv4net</format>
+      <description>IPv4 prefix to match</description>
+    </valueHelp>
+    <valueHelp>
+      <format>ipv4range</format>
+      <description>IPv4 address range to match</description>
+    </valueHelp>
+    <valueHelp>
+      <format>!ipv4</format>
+      <description>Match everything except the specified address</description>
+    </valueHelp>
+    <valueHelp>
+      <format>!ipv4net</format>
+      <description>Match everything except the specified prefix</description>
+    </valueHelp>
+    <valueHelp>
+      <format>!ipv4range</format>
+      <description>Match everything except the specified range</description>
+    </valueHelp>
+    <constraint>
+      <validator name="ipv4-address"/>
+      <validator name="ipv4-prefix"/>
+      <validator name="ipv4-range"/>
+      <validator name="ipv4-address-exclude"/>
+      <validator name="ipv4-prefix-exclude"/>
+      <validator name="ipv4-range-exclude"/>
+    </constraint>
+  </properties>
+</leafNode>
diff --git a/interface-definitions/include/nat-port.xml.i b/interface-definitions/include/nat-port.xml.i
new file mode 100644
index 000000000..24803ae05
--- /dev/null
+++ b/interface-definitions/include/nat-port.xml.i
@@ -0,0 +1,17 @@
+<leafNode name="port">
+  <properties>
+    <help>Port number</help>
+    <valueHelp>
+      <format>1-65535</format>
+      <description>Numeric IP port</description>
+    </valueHelp>
+    <valueHelp>
+      <format>start-end</format>
+      <description>Numbered port range (e.g., 1001-1005)</description>
+    </valueHelp>
+    <valueHelp>
+      <format> </format>
+      <description>\n\nMultiple destination ports can be specified as a comma-separated list.\nThe whole list can also be negated using '!'.\nFor example: '!22,telnet,http,123,1001-1005'</description>
+    </valueHelp>
+  </properties>
+</leafNode>
diff --git a/interface-definitions/include/nat-rule.xml.i b/interface-definitions/include/nat-rule.xml.i
new file mode 100644
index 000000000..f62a08987
--- /dev/null
+++ b/interface-definitions/include/nat-rule.xml.i
@@ -0,0 +1,303 @@
+<tagNode name="rule">
+  <properties>
+    <help>Rule number for NAT</help>
+    <valueHelp>
+      <format>1-9999</format>
+      <description>Number for this NAT rule</description>
+    </valueHelp>
+    <constraint>
+      <validator name="numeric" argument="--range 1-9999"/>
+    </constraint>
+    <constraintErrorMessage>NAT rule number must be between 1 and 9999</constraintErrorMessage>
+  </properties>
+  <children>
+    <leafNode name="description">
+      <properties>
+        <help>Rule description</help>
+      </properties>
+    </leafNode>
+    <node name="destination">
+      <properties>
+        <help>NAT destination parameters</help>
+      </properties>
+      <children>
+        #include <include/nat-address.xml.i>
+        #include <include/nat-port.xml.i>
+      </children>
+    </node>
+    <leafNode name="disable">
+      <properties>
+        <help>Disable NAT rule</help>
+        <valueless/>
+      </properties>
+    </leafNode>
+    <leafNode name="exclude">
+      <properties>
+        <help>Exclude packets matching this rule from NAT</help>
+        <valueless/>
+      </properties>
+    </leafNode>
+    <leafNode name="log">
+      <properties>
+        <help>NAT rule logging</help>
+        <valueless/>
+      </properties>
+    </leafNode>
+    <leafNode name="protocol">
+      <properties>
+        <help>Protocol to NAT</help>
+        <completionHelp>
+          <list>all ip hopopt icmp igmp ggp ipencap st tcp egp igp pup udp tcp_udp hmp xns-idp rdp iso-tp4 dccp xtp ddp idpr-cmtp ipv6 ipv6-route ipv6-frag idrp rsvp gre esp ah skip ipv6-icmp ipv6-nonxt ipv6-opts rspf vmtp eigrp ospf ax.25 ipip etherip encap 99 pim ipcomp vrrp l2tp isis sctp fc mobility-header udplite mpls-in-ip manet hip shim6 wesp rohc</list>
+        </completionHelp>
+        <valueHelp>
+          <format>all</format>
+          <description>All IP protocols</description>
+        </valueHelp>
+        <valueHelp>
+          <format>ip</format>
+          <description>Internet Protocol, pseudo protocol number</description>
+        </valueHelp>
+        <valueHelp>
+          <format>hopopt</format>
+          <description>IPv6 Hop-by-Hop Option [RFC1883]</description>
+        </valueHelp>
+        <valueHelp>
+          <format>icmp</format>
+          <description>internet control message protocol</description>
+        </valueHelp>
+        <valueHelp>
+          <format>igmp</format>
+          <description>Internet Group Management</description>
+        </valueHelp>
+        <valueHelp>
+          <format>ggp</format>
+          <description>gateway-gateway protocol</description>
+        </valueHelp>
+        <valueHelp>
+          <format>ipencap</format>
+          <description>IP encapsulated in IP (officially IP)</description>
+        </valueHelp>
+        <valueHelp>
+          <format>st</format>
+          <description>ST datagram mode</description>
+        </valueHelp>
+        <valueHelp>
+          <format>tcp</format>
+          <description>transmission control protocol</description>
+        </valueHelp>
+        <valueHelp>
+          <format>egp</format>
+          <description>exterior gateway protocol</description>
+        </valueHelp>
+        <valueHelp>
+          <format>igp</format>
+          <description>any private interior gateway (Cisco)</description>
+        </valueHelp>
+        <valueHelp>
+          <format>pup</format>
+          <description>PARC universal packet protocol</description>
+        </valueHelp>
+        <valueHelp>
+          <format>udp</format>
+          <description>user datagram protocol</description>
+        </valueHelp>
+        <valueHelp>
+          <format>tcp_udp</format>
+          <description>Both TCP and UDP</description>
+        </valueHelp>
+        <valueHelp>
+          <format>hmp</format>
+          <description>host monitoring protocol</description>
+        </valueHelp>
+        <valueHelp>
+          <format>xns-idp</format>
+          <description>Xerox NS IDP</description>
+        </valueHelp>
+        <valueHelp>
+          <format>rdp</format>
+          <description>"reliable datagram" protocol</description>
+        </valueHelp>
+        <valueHelp>
+          <format>iso-tp4</format>
+          <description>ISO Transport Protocol class 4 [RFC905]</description>
+        </valueHelp>
+        <valueHelp>
+          <format>dccp</format>
+          <description>Datagram Congestion Control Prot. [RFC4340]</description>
+        </valueHelp>
+        <valueHelp>
+          <format>xtp</format>
+          <description>Xpress Transfer Protocol</description>
+        </valueHelp>
+        <valueHelp>
+          <format>ddp</format>
+          <description>Datagram Delivery Protocol</description>
+        </valueHelp>
+        <valueHelp>
+          <format>idpr-cmtp</format>
+          <description>IDPR Control Message Transport</description>
+        </valueHelp>
+        <valueHelp>
+          <format>Ipv6</format>
+          <description>Internet Protocol, version 6</description>
+        </valueHelp>
+        <valueHelp>
+          <format>ipv6-route</format>
+          <description>Routing Header for IPv6</description>
+        </valueHelp>
+        <valueHelp>
+          <format>ipv6-frag</format>
+          <description>Fragment Header for IPv6</description>
+        </valueHelp>
+        <valueHelp>
+          <format>idrp</format>
+          <description>Inter-Domain Routing Protocol</description>
+        </valueHelp>
+        <valueHelp>
+          <format>rsvp</format>
+          <description>Reservation Protocol</description>
+        </valueHelp>
+        <valueHelp>
+          <format>gre</format>
+          <description>General Routing Encapsulation</description>
+        </valueHelp>
+        <valueHelp>
+          <format>esp</format>
+          <description>Encap Security Payload [RFC2406]</description>
+        </valueHelp>
+        <valueHelp>
+          <format>ah</format>
+          <description>Authentication Header [RFC2402]</description>
+        </valueHelp>
+        <valueHelp>
+          <format>skip</format>
+          <description>SKIP</description>
+        </valueHelp>
+        <valueHelp>
+          <format>ipv6-icmp</format>
+          <description>ICMP for IPv6</description>
+        </valueHelp>
+        <valueHelp>
+          <format>ipv6-nonxt</format>
+          <description>No Next Header for IPv6</description>
+        </valueHelp>
+        <valueHelp>
+          <format>ipv6-opts</format>
+          <description>Destination Options for IPv6</description>
+        </valueHelp>
+        <valueHelp>
+          <format>rspf</format>
+          <description>Radio Shortest Path First (officially CPHB)</description>
+        </valueHelp>
+        <valueHelp>
+          <format>vmtp</format>
+          <description>Versatile Message Transport</description>
+        </valueHelp>
+        <valueHelp>
+          <format>eigrp</format>
+          <description>Enhanced Interior Routing Protocol (Cisco)</description>
+        </valueHelp>
+        <valueHelp>
+          <format>ospf</format>
+          <description>Open Shortest Path First IGP</description>
+        </valueHelp>
+        <valueHelp>
+          <format>ax.25</format>
+          <description>AX.25 frames</description>
+        </valueHelp>
+        <valueHelp>
+          <format>ipip</format>
+          <description>IP-within-IP Encapsulation Protocol</description>
+        </valueHelp>
+        <valueHelp>
+          <format>etherip</format>
+          <description>Ethernet-within-IP Encapsulation [RFC3378]</description>
+        </valueHelp>
+        <valueHelp>
+          <format>encap</format>
+          <description>Yet Another IP encapsulation [RFC1241]</description>
+        </valueHelp>
+        <valueHelp>
+          <format>99</format>
+          <description>Any private encryption scheme</description>
+        </valueHelp>
+        <valueHelp>
+          <format>pim</format>
+          <description>Protocol Independent Multicast</description>
+        </valueHelp>
+        <valueHelp>
+          <format>ipcomp</format>
+          <description>IP Payload Compression Protocol</description>
+        </valueHelp>
+        <valueHelp>
+          <format>vrrp</format>
+          <description>Virtual Router Redundancy Protocol [RFC5798]</description>
+        </valueHelp>
+        <valueHelp>
+          <format>l2tp</format>
+          <description>Layer Two Tunneling Protocol [RFC2661]</description>
+        </valueHelp>
+        <valueHelp>
+          <format>isis</format>
+          <description>IS-IS over IPv4</description>
+        </valueHelp>
+        <valueHelp>
+          <format>sctp</format>
+          <description>Stream Control Transmission Protocol</description>
+        </valueHelp>
+        <valueHelp>
+          <format>fc</format>
+          <description>Fibre Channel</description>
+        </valueHelp>
+        <valueHelp>
+          <format>mobility-header</format>
+          <description>Mobility Support for IPv6 [RFC3775]</description>
+        </valueHelp>
+        <valueHelp>
+          <format>udplite</format>
+          <description>UDP-Lite [RFC3828]</description>
+        </valueHelp>
+        <valueHelp>
+          <format>mpls-in-ip</format>
+          <description>MPLS-in-IP [RFC4023]</description>
+        </valueHelp>
+        <valueHelp>
+          <format>manet</format>
+          <description>MANET Protocols [RFC5498]</description>
+        </valueHelp>
+        <valueHelp>
+          <format>hip</format>
+          <description>Host Identity Protocol</description>
+        </valueHelp>
+        <valueHelp>
+          <format>shim6</format>
+          <description>Shim6 Protocol</description>
+        </valueHelp>
+        <valueHelp>
+          <format>wesp</format>
+          <description>Wrapped Encapsulating Security Payload</description>
+        </valueHelp>
+        <valueHelp>
+          <format>rohc</format>
+          <description>Robust Header Compression</description>
+        </valueHelp>
+        <valueHelp>
+          <format>0-255</format>
+          <description>IP protocol number</description>
+        </valueHelp>
+        <constraint>
+          <validator name="ip-protocol"/>
+        </constraint>
+      </properties>
+    </leafNode>
+    <node name="source">
+      <properties>
+        <help>NAT source parameters</help>
+      </properties>
+      <children>
+        #include <include/nat-address.xml.i>
+        #include <include/nat-port.xml.i>
+      </children>
+    </node>
+  </children>
+</tagNode>
diff --git a/interface-definitions/include/nat-translation-port.xml.i b/interface-definitions/include/nat-translation-port.xml.i
new file mode 100644
index 000000000..93de471e3
--- /dev/null
+++ b/interface-definitions/include/nat-translation-port.xml.i
@@ -0,0 +1,13 @@
+<leafNode name="port">
+  <properties>
+    <help>Port number</help>
+    <valueHelp>
+      <format>1-65535</format>
+      <description>Numeric IP port</description>
+    </valueHelp>
+    <valueHelp>
+      <format>&lt;start&gt;-&lt;end&gt;</format>
+      <description>Numbered port range (e.g., 1001-1005)</description>
+    </valueHelp>
+  </properties>
+</leafNode>
diff --git a/interface-definitions/nat.xml.in b/interface-definitions/nat.xml.in
new file mode 100644
index 000000000..af9dd1eff
--- /dev/null
+++ b/interface-definitions/nat.xml.in
@@ -0,0 +1,115 @@
+<?xml version="1.0"?>
+<interfaceDefinition>
+  <node name="nat" owner="sudo ${vyos_conf_scripts_dir}/nat.py">
+    <properties>
+      <help>Network Address Translation (NAT) parameters</help>
+      <priority>220</priority>
+    </properties>
+    <children>
+      <node name="destination">
+        <properties>
+          <help>Destination NAT settings</help>
+        </properties>
+        <children>
+          #include <include/nat-rule.xml.i>
+          <tagNode name="rule">
+            <children>
+              <leafNode name="inbound-interface">
+                <properties>
+                  <help>Inbound interface of NAT traffic</help>
+                  <completionHelp>
+                    <script>${vyos_completion_dir}/list_interfaces.py</script>
+                  </completionHelp>
+                </properties>
+              </leafNode>
+              <node name="translation">
+                <properties>
+                  <help>Inside NAT IP (destination NAT only)</help>
+                </properties>
+                <children>
+                  <leafNode name="address">
+                    <properties>
+                      <help>IP address, subnet, or range</help>
+                      <valueHelp>
+                        <format>ipv4</format>
+                        <description>IPv4 address to match</description>
+                      </valueHelp>
+                      <valueHelp>
+                        <format>ipv4net</format>
+                        <description>IPv4 prefix to match</description>
+                      </valueHelp>
+                      <valueHelp>
+                        <format>ipv4range</format>
+                        <description>IPv4 address range to match</description>
+                      </valueHelp>
+                      <!-- TODO: add general iptables constraint script -->
+                    </properties>
+                  </leafNode>
+                  #include <include/nat-translation-port.xml.i>
+                </children>
+              </node>
+            </children>
+          </tagNode>
+        </children>
+      </node>
+      <node name="source">
+        <properties>
+          <help>Source NAT settings</help>
+        </properties>
+        <children>
+          #include <include/nat-rule.xml.i>
+          <tagNode name="rule">
+            <children>
+              <leafNode name="outbound-interface">
+                <properties>
+                  <help>Outbound interface of NAT traffic</help>
+                  <completionHelp>
+                    <script>${vyos_completion_dir}/list_interfaces.py</script>
+                  </completionHelp>
+                </properties>
+              </leafNode>
+              <node name="translation">
+                <properties>
+                  <help>Outside NAT IP (source NAT only)</help>
+                </properties>
+                <children>
+                  <leafNode name="address">
+                    <properties>
+                      <help>IP address, subnet, or range</help>
+                      <completionHelp>
+                        <list>masquerade</list>
+                      </completionHelp>
+                      <valueHelp>
+                        <format>ipv4</format>
+                        <description>IPv4 address to match</description>
+                      </valueHelp>
+                      <valueHelp>
+                        <format>ipv4net</format>
+                        <description>IPv4 prefix to match</description>
+                      </valueHelp>
+                      <valueHelp>
+                        <format>ipv4range</format>
+                        <description>IPv4 address range to match</description>
+                      </valueHelp>
+                      <valueHelp>
+                        <format>masquerade</format>
+                        <description>NAT to the primary address of outbound-interface</description>
+                      </valueHelp>
+                      <constraint>
+                        <validator name="ipv4-prefix"/>
+                        <validator name="ipv4-address"/>
+                        <validator name="ipv4-range"/>
+                        <regex>(masquerade)</regex>
+                      </constraint>
+                    </properties>
+                  </leafNode>
+                  #include <include/nat-translation-port.xml.i>
+                </children>
+              </node>
+            </children>
+          </tagNode>
+        </children>
+      </node>
+    </children>
+  </node>
+</interfaceDefinition>
diff --git a/op-mode-definitions/nat.xml b/op-mode-definitions/nat.xml
new file mode 100644
index 000000000..ffaa2cba3
--- /dev/null
+++ b/op-mode-definitions/nat.xml
@@ -0,0 +1,98 @@
+<?xml version="1.0" encoding="UTF-8"?>

+<interfaceDefinition>

+  <node name="show">

+    <children>

+      <node name="nat">

+        <properties>

+          <help>Show Network Address Translation (NAT) information</help>

+        </properties>

+        <children>

+          <node name="source">

+            <properties>

+              <help>Show source Network Address Translation (NAT) information</help>

+            </properties>

+            <children>

+              <node name="rules">

+                <properties>

+                  <help>Show configured source NAT rules</help>

+                </properties>

+                <command>echo To be migrated to Python - https://phabricator.vyos.net/T2459</command>

+              </node>

+              <node name="statistics">

+                <properties>

+                  <help>Show statistics for configured source NAT rules</help>

+                </properties>

+                <command>${vyos_op_scripts_dir}/show_nat_statistics.py --source</command>

+              </node>

+              <node name="translations">

+                <properties>

+                  <help>Show active source NAT translations</help>

+                </properties>

+                <children>

+                  <tagNode name="address">

+                    <properties>

+                      <help>Show active source NAT translations for an IP address</help>

+                      <completionHelp>

+                        <list>&lt;x.x.x.x&gt;</list>

+                      </completionHelp>

+                    </properties>

+                    <command>${vyos_op_scripts_dir}/to_be_migrated/vyatta-nat-translations.pl --type=source --verbose --ipaddr="$6"</command>

+                  </tagNode>

+                  <node name="detail">

+                    <properties>

+                      <help>Show active source NAT translations detail</help>

+                    </properties>

+                    <command>${vyos_op_scripts_dir}/to_be_migrated/vyatta-nat-translations.pl --type=source --verbose</command>

+                  </node>

+                </children>

+                <command>${vyos_op_scripts_dir}/to_be_migrated/vyatta-nat-translations.pl --type=source</command>

+              </node>

+            </children>

+          </node>

+          <node name="destination">

+            <properties>

+              <help>Show destination Network Address Translation (NAT) information</help>

+            </properties>

+            <children>

+              <node name="rules">

+                <properties>

+                  <help>Show configured destination NAT rules</help>

+                </properties>

+                <command>echo To be migrated to Python - https://phabricator.vyos.net/T2459</command>

+              </node>

+              <node name="statistics">

+                <properties>

+                  <help>Show statistics for configured destination NAT rules</help>

+                </properties>

+                <command>${vyos_op_scripts_dir}/show_nat_statistics.py --destination</command>

+              </node>

+              <node name="translations">

+                <properties>

+                  <help>Show active destination NAT translations</help>

+                </properties>

+                <children>

+                  <tagNode name="address">

+                    <properties>

+                      <help>Show active NAT destination translations for an IP address</help>

+                      <completionHelp>

+                        <list>&lt;x.x.x.x&gt;</list>

+                      </completionHelp>

+                    </properties>

+                    <command>${vyos_op_scripts_dir}/to_be_migrated/vyatta-nat-translations.pl --type=destination --verbose --ipaddr="$6"</command>

+                  </tagNode>

+                  <node name="detail">

+                    <properties>

+                      <help>Show active destination NAT translations detail</help>

+                    </properties>

+                    <command>${vyos_op_scripts_dir}/to_be_migrated/vyatta-nat-translations.pl --type=destination --verbose</command>

+                  </node>

+                </children>

+                <command>${vyos_op_scripts_dir}/to_be_migrated/vyatta-nat-translations.pl --type=destination</command>

+              </node>

+            </children>

+          </node>

+        </children>

+      </node>

+    </children>

+  </node>

+</interfaceDefinition>

diff --git a/src/conf_mode/nat.py b/src/conf_mode/nat.py
new file mode 100755
index 000000000..5cb1af1f1
--- /dev/null
+++ b/src/conf_mode/nat.py
@@ -0,0 +1,259 @@
+#!/usr/bin/env python3
+#
+# Copyright (C) 2020 VyOS maintainers and contributors
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License version 2 or later as
+# published by the Free Software Foundation.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+import jmespath
+import json
+import os
+
+from copy import deepcopy
+from sys import exit
+from netifaces import interfaces
+
+from vyos.config import Config
+from vyos.template import render
+from vyos.util import call, cmd
+from vyos.validate import is_addr_assigned
+from vyos import ConfigError
+
+default_config_data = {
+    'deleted': False,
+    'destination': [],
+    'helper_functions': None,
+    'pre_ct_helper': '',
+    'pre_ct_conntrack': '',
+    'out_ct_helper': '',
+    'out_ct_conntrack': '',
+    'source': []
+}
+
+iptables_nat_config = '/tmp/vyos-nat-rules.nft'
+
+def _check_kmod():
+    """ load required Kernel modules """
+    modules = ['nft_nat', 'nft_chain_nat_ipv4']
+    for module in modules:
+        if not os.path.exists(f'/sys/module/{module}'):
+            if call(f'modprobe {module}') != 0:
+                raise ConfigError(f'Loading Kernel module {module} failed')
+
+
+def get_handler(json, chain, target):
+    """ Get nftable rule handler number of given chain/target combination.
+    Handler is required when adding NAT/Conntrack helper targets """
+    for x in json:
+        if x['chain'] != chain:
+            continue
+        if x['target'] != target:
+            continue
+        return x['handle']
+
+    return None
+
+
+def verify_rule(rule, err_msg):
+    """ Common verify steps used for both source and destination NAT """
+    if rule['translation_port'] or rule['dest_port'] or rule['source_port']:
+        if rule['protocol'] not in ['tcp', 'udp', 'tcp_udp']:
+            proto = rule['protocol']
+            raise ConfigError(f'{err_msg} ports can only be specified when protocol is "tcp", "udp" or "tcp_udp" (currently "{proto}")')
+
+        if '/' in rule['translation_address']:
+            raise ConfigError(f'{err_msg}\n' \
+                             'Cannot use ports with an IPv4net type translation address as it\n' \
+                             'statically maps a whole network of addresses onto another\n' \
+                             'network of addresses')
+
+    if not rule['translation_address']:
+        raise ConfigError(f'{err_msg} translation address not specified')
+    else:
+        addr = rule['translation_address']
+        if addr != 'masquerade' and not is_addr_assigned(addr):
+            print(f'Warning: IP address {addr} does not exist on the system!')
+
+
+def parse_source_destination(conf, source_dest):
+    """ Common wrapper to read in both NAT source and destination CLI """
+    tmp = []
+    base_level = ['nat', source_dest]
+    conf.set_level(base_level)
+    for number in conf.list_nodes(['rule']):
+        rule = {
+            'description': '',
+            'dest_address': '',
+            'dest_port': '',
+            'disabled': False,
+            'exclude': False,
+            'interface_in': '',
+            'interface_out': '',
+            'log': False,
+            'protocol': 'all',
+            'number': number,
+            'source_address': '',
+            'source_port': '',
+            'translation_address': '',
+            'translation_port': ''
+        }
+        conf.set_level(base_level + ['rule', number])
+
+        if conf.exists(['description']):
+            rule['description'] = conf.return_value(['description'])
+
+        if conf.exists(['destination', 'address']):
+            rule['dest_address'] = conf.return_value(['destination', 'address'])
+
+        if conf.exists(['destination', 'port']):
+            rule['dest_port'] = conf.return_value(['destination', 'port'])
+
+        if conf.exists(['disable']):
+            rule['disabled'] = True
+
+        if conf.exists(['exclude']):
+            rule['exclude'] = True
+
+        if conf.exists(['inbound-interface']):
+            rule['interface_in'] = conf.return_value(['inbound-interface'])
+
+        if conf.exists(['outbound-interface']):
+            rule['interface_out'] = conf.return_value(['outbound-interface'])
+
+        if conf.exists(['log']):
+            rule['log'] = True
+
+        if conf.exists(['protocol']):
+            rule['protocol'] = conf.return_value(['protocol'])
+
+        if conf.exists(['source', 'address']):
+            rule['source_address'] = conf.return_value(['source', 'address'])
+
+        if conf.exists(['source', 'port']):
+            rule['source_port'] = conf.return_value(['source', 'port'])
+
+        if conf.exists(['translation', 'address']):
+            rule['translation_address'] = conf.return_value(['translation', 'address'])
+
+        if conf.exists(['translation', 'port']):
+            rule['translation_port'] = conf.return_value(['translation', 'port'])
+
+        tmp.append(rule)
+
+    return tmp
+
+def get_config():
+    nat = deepcopy(default_config_data)
+    conf = Config()
+
+    # read in current nftable (once) for further processing
+    tmp = cmd('nft -j list table raw')
+    nftable_json = json.loads(tmp)
+
+    # condense the full JSON table into a list with only relevand informations
+    pattern = 'nftables[?rule].rule[?expr[].jump].{chain: chain, handle: handle, target: expr[].jump.target | [0]}'
+    condensed_json = jmespath.search(pattern, nftable_json)
+
+    if not conf.exists(['nat']):
+        nat['helper_functions'] = 'remove'
+
+        # Retrieve current table handler positions
+        nat['pre_ct_ignore'] = get_handler(condensed_json, 'PREROUTING', 'VYATTA_CT_HELPER')
+        nat['pre_ct_conntrack'] = get_handler(condensed_json, 'PREROUTING', 'NAT_CONNTRACK')
+        nat['out_ct_ignore'] = get_handler(condensed_json, 'OUTPUT', 'VYATTA_CT_HELPER')
+        nat['out_ct_conntrack'] = get_handler(condensed_json, 'OUTPUT', 'NAT_CONNTRACK')
+
+        nat['deleted'] = True
+
+        return nat
+
+    # check if NAT connection tracking helpers need to be set up - this has to
+    # be done only once
+    if not get_handler(condensed_json, 'PREROUTING', 'NAT_CONNTRACK'):
+        nat['helper_functions'] = 'add'
+
+        # Retrieve current table handler positions
+        nat['pre_ct_ignore'] = get_handler(condensed_json, 'PREROUTING', 'VYATTA_CT_IGNORE')
+        nat['pre_ct_conntrack'] = get_handler(condensed_json, 'PREROUTING', 'VYATTA_CT_PREROUTING_HOOK')
+        nat['out_ct_ignore'] = get_handler(condensed_json, 'OUTPUT', 'VYATTA_CT_IGNORE')
+        nat['out_ct_conntrack'] = get_handler(condensed_json, 'OUTPUT', 'VYATTA_CT_OUTPUT_HOOK')
+
+    # set config level for parsing in NAT configuration
+    conf.set_level(['nat'])
+
+    # use a common wrapper function to read in the source / destination
+    # tree from the config - thus we do not need to replicate almost the
+    # same code :-)
+    for tgt in ['source', 'destination']:
+        nat[tgt] = parse_source_destination(conf, tgt)
+
+    return nat
+
+def verify(nat):
+    if nat['deleted']:
+        # no need to verify the CLI as NAT is going to be deactivated
+        return None
+
+    if nat['helper_functions']:
+        if not (nat['pre_ct_ignore'] or nat['pre_ct_conntrack'] or nat['out_ct_ignore'] or nat['out_ct_conntrack']):
+            raise Exception('could not determine nftable ruleset handlers')
+
+    for rule in nat['source']:
+        interface = rule['interface_out']
+        err_msg = f"Source NAT configuration error in rule {rule['number']}:"
+
+        if interface and interface not in interfaces():
+            print(f'NAT configuration warning: interface {interface} does not exist on this system')
+
+        if not rule['interface_out']:
+            raise ConfigError(f'{err_msg} outbound-interface not specified')
+
+        # common rule verification
+        verify_rule(rule, err_msg)
+
+    for rule in nat['destination']:
+        interface = rule['interface_in']
+        err_msg = f"Destination NAT configuration error in rule {rule['number']}:"
+
+        if interface and interface not in interfaces():
+            print(f'NAT configuration warning: interface {interface} does not exist on this system')
+
+        if not rule['interface_in']:
+            raise ConfigError(f'{err_msg} inbound-interface not specified')
+
+        # common rule verification
+        verify_rule(rule, err_msg)
+
+    return None
+
+def generate(nat):
+    render(iptables_nat_config, 'firewall/nftables-nat.tmpl', nat, trim_blocks=True, permission=0o755)
+
+    return None
+
+def apply(nat):
+    cmd(f'{iptables_nat_config}')
+    if os.path.isfile(iptables_nat_config):
+        os.unlink(iptables_nat_config)
+
+    return None
+
+if __name__ == '__main__':
+    try:
+        _check_kmod()
+        c = get_config()
+        verify(c)
+        generate(c)
+        apply(c)
+    except ConfigError as e:
+        print(e)
+        exit(1)
diff --git a/src/migration-scripts/nat/4-to-5 b/src/migration-scripts/nat/4-to-5
new file mode 100755
index 000000000..dda191719
--- /dev/null
+++ b/src/migration-scripts/nat/4-to-5
@@ -0,0 +1,58 @@
+#!/usr/bin/env python3
+#
+# Copyright (C) 2020 VyOS maintainers and contributors
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License version 2 or later as
+# published by the Free Software Foundation.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+# Drop the enable/disable from the nat "log" node. If log node is specified
+# it is "enabled"
+
+from sys import argv,exit
+from vyos.configtree import ConfigTree
+
+if (len(argv) < 1):
+    print("Must specify file name!")
+    exit(1)
+
+file_name = argv[1]
+
+with open(file_name, 'r') as f:
+    config_file = f.read()
+
+config = ConfigTree(config_file)
+
+if not config.exists(['nat']):
+    # Nothing to do
+    exit(0)
+else:
+    for direction in ['source', 'destination']:
+        if not config.exists(['nat', direction]):
+            continue
+
+        for rule in config.list_nodes(['nat', direction, 'rule']):
+            base = ['nat', direction, 'rule', rule]
+
+            # Check if the log node exists and if log is enabled,
+            # migrate it to the new valueless 'log' node
+            if config.exists(base + ['log']):
+                tmp = config.return_value(base + ['log'])
+                config.delete(base + ['log'])
+                if tmp == 'enable':
+                    config.set(base + ['log'])
+
+    try:
+        with open(file_name, 'w') as f:
+            f.write(config.to_string())
+    except OSError as e:
+        print("Failed to save the modified config: {}".format(e))
+        exit(1)
diff --git a/src/op_mode/show_nat_statistics.py b/src/op_mode/show_nat_statistics.py
new file mode 100755
index 000000000..0b53112f2
--- /dev/null
+++ b/src/op_mode/show_nat_statistics.py
@@ -0,0 +1,63 @@
+#!/usr/bin/env python3
+#
+# Copyright (C) 2018 VyOS maintainers and contributors
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License version 2 or later as
+# published by the Free Software Foundation.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+import jmespath
+import json
+
+from argparse import ArgumentParser
+from jinja2 import Template
+from sys import exit
+from vyos.util import cmd
+
+OUT_TMPL_SRC="""
+rule      pkts        bytes   interface
+----      ----        -----   ---------
+{% for r in output %}
+{%- if r.comment -%}
+{%- set packets   = r.counter.packets -%}
+{%- set bytes     = r.counter.bytes -%}
+{%- set interface = r.interface -%}
+{# remove rule comment prefix #}
+{%- set comment   = r.comment | replace('SRC-NAT-', '') | replace('DST-NAT-', '') | replace(' tcp_udp', '') -%}
+{{ "%-4s" | format(comment) }} {{ "%9s" | format(packets) }} {{ "%12s" | format(bytes) }}   {{ interface }}
+{%- endif %}
+{% endfor %}
+"""
+
+parser = ArgumentParser()
+group = parser.add_mutually_exclusive_group()
+group.add_argument("--source", help="Show statistics for configured source NAT rules", action="store_true")
+group.add_argument("--destination", help="Show statistics for configured destination NAT rules", action="store_true")
+args = parser.parse_args()
+
+if args.source or args.destination:
+    tmp = cmd('sudo nft -j list table nat')
+    tmp = json.loads(tmp)
+
+    source = r"nftables[?rule.chain=='POSTROUTING'].rule.{chain: chain, handle: handle, comment: comment, counter: expr[].counter | [0], interface: expr[].match.right | [0] }"
+    destination = r"nftables[?rule.chain=='PREROUTING'].rule.{chain: chain, handle: handle, comment: comment, counter: expr[].counter | [0], interface: expr[].match.right | [0] }"
+    data = {
+        'output' : jmespath.search(source if args.source else destination, tmp),
+        'direction' : 'source' if args.source else 'destination'
+    }
+
+    tmpl = Template(OUT_TMPL_SRC, lstrip_blocks=True)
+    print(tmpl.render(data))
+    exit(0)
+else:
+    parser.print_help()
+    exit(1)
+
diff --git a/src/op_mode/to_be_migrated/vyatta-nat-translations.pl b/src/op_mode/to_be_migrated/vyatta-nat-translations.pl
new file mode 100755
index 000000000..94ed74bad
--- /dev/null
+++ b/src/op_mode/to_be_migrated/vyatta-nat-translations.pl
@@ -0,0 +1,267 @@
+#!/usr/bin/perl
+#
+# Module: vyatta-nat-translate.pl
+# 
+# **** License ****
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License version 2 as
+# published by the Free Software Foundation.
+# 
+# This program is distributed in the hope that it will be useful, but
+# WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+# General Public License for more details.
+# 
+# This code was originally developed by Vyatta, Inc.
+# Portions created by Vyatta are Copyright (C) 2007 Vyatta, Inc.
+# All Rights Reserved.
+# 
+# Author: Stig Thormodsrud
+# Date: July 2008
+# Description: Script to display nat translations
+# 
+# **** End License ****
+#
+
+use Getopt::Long;
+use XML::Simple;
+use Data::Dumper;
+use POSIX;
+
+use warnings;
+use strict;
+
+my $dump = 0;
+my ($xml_file, $verbose, $proto, $stats, $ipaddr, $pipe);
+my $type;
+my $verbose_format = "%-20s %-18s %-20s %-18s\n";
+my $format         = "%-20s %-20s %-4s  %-8s";
+
+sub add_xml_root {
+    my $xml = shift;
+
+    $xml = '<data>' . $xml . '</data>';
+    return $xml;
+}
+
+
+sub read_xml_file {
+    my $file = shift;
+
+    local($/, *FD);  # slurp mode
+    open FD, "<", $file or die "Couldn't open $file\n";
+    my $xml = <FD>;
+    close FD;
+    return $xml;
+}
+
+sub print_xml {
+    my $data = shift;
+    print Dumper($data); 
+}
+
+sub guess_snat_dnat {
+    my ($src, $dst) = @_;
+
+    if ($src->{original} eq $dst->{reply}) {
+	return "dnat";
+    }
+    if ($dst->{original} eq $src->{reply}) {
+	return "snat";
+    }
+    return "unkn";
+}
+
+sub nat_print_xml {
+    my ($data, $type) = @_;
+
+    my $flow = 0;
+
+    my %flowh;
+    while (1) {
+	my $meta = 0;
+	last if ! defined $data->{flow}[$flow];
+	my $flow_ref = $data->{flow}[$flow];
+	my $flow_type = $flow_ref->{type};
+	my (%src, %dst, %sport, %dport, %proto);
+	my (%packets, %bytes);
+	my $timeout = undef;
+	my $uses = undef;
+	while (1) {
+	    my $meta_ref = $flow_ref->{meta}[$meta];
+	    last if ! defined $meta_ref;
+	    my $dir = $meta_ref->{direction};
+	    if ($dir eq 'original' or $dir eq 'reply') {
+		my $l3_ref    = $meta_ref->{layer3}[0];
+		my $l4_ref    = $meta_ref->{layer4}[0];
+		my $count_ref = $meta_ref->{counters}[0];
+		if (defined $l3_ref) {
+		    $src{$dir} = $l3_ref->{src}[0];
+		    $dst{$dir} = $l3_ref->{dst}[0];
+		    if (defined $l4_ref) {
+			$sport{$dir} = $l4_ref->{sport}[0];
+			$dport{$dir} = $l4_ref->{dport}[0];
+			$proto{$dir} = $l4_ref->{protoname};
+		    }
+		}
+		if (defined $stats and defined $count_ref) {
+		    $packets{$dir} = $count_ref->{packets}[0];
+		    $bytes{$dir}   = $count_ref->{bytes}[0];
+		}
+	    } elsif ($dir eq 'independent') {
+		$timeout = $meta_ref->{timeout}[0];
+		$uses    = $meta_ref->{'use'}[0];
+	    }
+	    $meta++;
+	}
+	my ($proto, $in_src, $in_dst, $out_src, $out_dst);
+	$proto    = $proto{original};
+	$in_src   = "$src{original}";
+	$in_src  .= ":$sport{original}" if defined $sport{original};
+	$in_dst   = "$dst{original}";
+	$in_dst  .= ":$dport{original}" if defined $dport{original};
+	$out_src  = "$dst{reply}";
+	$out_src .= ":$dport{reply}" if defined $dport{reply};
+	$out_dst  = "$src{reply}";
+	$out_dst .= ":$sport{reply}" if defined $sport{reply};
+	if (defined $verbose) {
+	    printf($verbose_format, $in_src, $in_dst, $out_src, $out_dst);
+	}
+#	if (! defined $type) {
+#	    $type = guess_snat_dnat(\%src, \%dst);
+#	}
+	if (defined $type) {
+	    my ($from, $to);
+	    if ($type eq 'source') {
+		$from = "$src{original}";
+		$to   = "$dst{reply}";
+		if (defined $sport{original} and defined $dport{reply}) {
+		    if ($sport{original} ne $dport{reply}) {
+			$from .= ":$sport{original}";
+			$to   .= ":$dport{reply}";
+		    }
+		}
+	    } else {
+		$from = "$dst{original}";
+		$to   = "$src{reply}";
+		if (defined $dport{original} and defined $sport{reply}) {
+		    if ($dport{original} ne $sport{reply}) {
+			$from .= ":$dport{original}";
+			$to   .= ":$sport{reply}";
+		    }
+		}
+	    }
+	    if (defined $verbose) {
+		print "  $proto: $from ==> $to";
+	    } else {
+		my $timeout2 = "";
+		if (defined $timeout) {
+		    $timeout2 = $timeout;
+		}
+		printf($format, $from, $to, $proto, $timeout2);
+		print " $flow_type" if defined $flow_type;
+		print "\n";
+	    }
+	}
+	if (defined $verbose) {
+	    print "  timeout: $timeout" if defined $timeout;
+	    print " use: $uses " if defined $uses;
+	    print " type: $flow_type" if defined $flow_type;
+	    print "\n";
+	}
+	if (defined $stats) {
+	    foreach my $dir ('original', 'reply') {
+		if (defined $packets{$dir}) {
+                    printf("  %-8s: packets %s, bytes %s\n",
+		           $dir, $packets{$dir}, $bytes{$dir});
+		}
+	    }
+	}
+	$flow++;
+    }
+    return $flow;
+}
+
+
+#
+# main
+#
+GetOptions("verbose"  => \$verbose,
+	   "proto=s"  => \$proto,
+	   "file=s"   => \$xml_file,
+	   "stats"    => \$stats,
+	   "type=s"   => \$type,
+	   "ipaddr=s" => \$ipaddr,
+	   "pipe"     => \$pipe,
+);
+
+my $conntrack = '/usr/sbin/conntrack';
+if  (! -f $conntrack) {
+    die "Package [conntrack] not installed";
+}
+
+die "Must specify NAT type!" if !defined($type);
+die "Unknown NAT type!" if (($type ne 'source') && ($type ne 'destination'));
+
+my $xs = XML::Simple->new(ForceArray => 1, KeepRoot => 0);
+my ($xml, $data);
+
+# flush stdout after every write for pipe mode
+$| = 1 if defined $pipe; 
+
+if (defined $verbose) {
+    printf($verbose_format, 'Pre-NAT src', 'Pre-NAT dst', 
+	   'Post-NAT src', 'Post-NAT dst');
+} else {
+    printf($format, 'Pre-NAT', 'Post-NAT', 'Prot', 'Timeout');
+    print " Type" if defined $pipe;
+    print "\n";
+}
+
+if (defined $xml_file) {
+    $xml = read_xml_file($xml_file);
+    $data = $xs->XMLin($xml);
+    if ($dump) {
+	print_xml($data);
+	exit;
+    }
+    nat_print_xml($data, 'snat');
+
+} elsif (defined $pipe) {
+    while ($xml = <STDIN>) {
+	$xml =~ s/\<\?xml version=\"1\.0\" encoding=\"utf-8\"\?\>//;
+	$xml =~ s/\<conntrack\>//;
+	$xml = add_xml_root($xml);
+	$data = $xs->XMLin($xml);
+	nat_print_xml($data, $type);
+    }
+} else {
+    if (defined $proto) {
+	$proto = "-p $proto" 
+    } else {
+	$proto = "";
+    }
+    if ($type eq 'source') {
+	my $ipopt = "";
+	if (defined $ipaddr) {
+	    $ipopt = "--orig-src $ipaddr";
+	} 
+	$xml = `sudo $conntrack -L -n $ipopt -o xml $proto 2>/dev/null`;
+	chomp $xml;
+	$data = undef;
+	$data = $xs->XMLin($xml) if ! $xml eq '';
+    }
+    if ($type eq 'destination') {
+	my $ipopt = "";
+	if (defined $ipaddr) {
+	    $ipopt = "--orig-dst $ipaddr";
+	} 
+	$xml = `sudo $conntrack -L -g $ipopt -o xml $proto 2>/dev/null`;
+	chomp $xml;
+	$data = undef;
+	$data = $xs->XMLin($xml) if ! $xml eq '';
+    }
+    nat_print_xml($data, $type) if defined $data;
+}
+
+# end of file
diff --git a/src/validators/ip-protocol b/src/validators/ip-protocol
new file mode 100755
index 000000000..078f8e319
--- /dev/null
+++ b/src/validators/ip-protocol
@@ -0,0 +1,41 @@
+#!/usr/bin/env python3
+#
+# Copyright (C) 2020 VyOS maintainers and contributors
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License version 2 or later as
+# published by the Free Software Foundation.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+import re
+from sys import argv,exit
+
+if __name__ == '__main__':
+    if len(argv) != 2:
+        exit(1)
+
+    input = argv[1]
+    try:
+        # IP protocol can be in the range 0 - 255, thus the range must end with 256
+        if int(input) in range(0, 256):
+            exit(0)
+    except ValueError:
+        pass
+
+    pattern = "!?\\b(all|ip|hopopt|icmp|igmp|ggp|ipencap|st|tcp|egp|igp|pup|udp|" \
+              "tcp_udp|hmp|xns-idp|rdp|iso-tp4|dccp|xtp|ddp|idpr-cmtp|ipv6|" \
+              "ipv6-route|ipv6-frag|idrp|rsvp|gre|esp|ah|skip|ipv6-icmp|" \
+              "ipv6-nonxt|ipv6-opts|rspf|vmtp|eigrp|ospf|ax.25|ipip|etherip|" \
+              "encap|99|pim|ipcomp|vrrp|l2tp|isis|sctp|fc|mobility-header|" \
+              "udplite|mpls-in-ip|manet|hip|shim6|wesp|rohc)\\b"
+    if re.match(pattern, input):
+        exit(0)
+
+    exit(1)
diff --git a/src/validators/ipv4-address-exclude b/src/validators/ipv4-address-exclude
new file mode 100755
index 000000000..80ad17d45
--- /dev/null
+++ b/src/validators/ipv4-address-exclude
@@ -0,0 +1,7 @@
+#!/bin/sh
+arg="$1"
+if [ "${arg:0:1}" != "!" ]; then
+  exit 1
+fi
+path=$(dirname "$0")
+${path}/ipv4-address "${arg:1}"
diff --git a/src/validators/ipv4-prefix-exclude b/src/validators/ipv4-prefix-exclude
new file mode 100755
index 000000000..4f7de400a
--- /dev/null
+++ b/src/validators/ipv4-prefix-exclude
@@ -0,0 +1,7 @@
+#!/bin/sh
+arg="$1"
+if [ "${arg:0:1}" != "!" ]; then
+  exit 1
+fi
+path=$(dirname "$0")
+${path}/ipv4-prefix "${arg:1}"
diff --git a/src/validators/ipv4-range b/src/validators/ipv4-range
new file mode 100755
index 000000000..ae3f3f163
--- /dev/null
+++ b/src/validators/ipv4-range
@@ -0,0 +1,33 @@
+#!/bin/bash
+
+# snippet from https://stackoverflow.com/questions/10768160/ip-address-converter
+ip2dec () {
+    local a b c d ip=$@
+    IFS=. read -r a b c d <<< "$ip"
+    printf '%d\n' "$((a * 256 ** 3 + b * 256 ** 2 + c * 256 + d))"
+}
+
+# Only run this if there is a hypen present in $1
+if [[ "$1" =~ "-" ]]; then
+  # This only works with real bash (<<<) - split IP addresses into array with
+  # hyphen as delimiter
+  readarray -d - -t strarr <<< $1
+
+  ipaddrcheck --is-ipv4-single ${strarr[0]}
+  if [ $? -gt 0 ]; then
+    exit 1
+  fi
+
+  ipaddrcheck --is-ipv4-single ${strarr[1]}
+  if [ $? -gt 0 ]; then
+    exit 1
+  fi
+
+  start=$(ip2dec ${strarr[0]})
+  stop=$(ip2dec ${strarr[1]})
+  if [ $start -ge $stop ]; then
+    exit 1
+  fi
+fi
+
+exit 0
diff --git a/src/validators/ipv4-range-exclude b/src/validators/ipv4-range-exclude
new file mode 100755
index 000000000..3787b4dec
--- /dev/null
+++ b/src/validators/ipv4-range-exclude
@@ -0,0 +1,7 @@
+#!/bin/sh
+arg="$1"
+if [ "${arg:0:1}" != "!" ]; then
+  exit 1
+fi
+path=$(dirname "$0")
+${path}/ipv4-range "${arg:1}"