T2898: add ndp-proxy service

VyOS CLI command
  set service ndp-proxy interface eth0 prefix 2001:db8::/64 mode 'static'

Will generate the following NDP proxy configuration

  $ cat /run/ndppd/ndppd.conf
  # autogenerated by service_ndp-proxy.py

  # This tells 'ndppd' how often to reload the route file /proc/net/ipv6_route
  route-ttl 30000

  # This sets up a listener, that will listen for any Neighbor Solicitation
  # messages, and respond to them according to a set of rules
  proxy eth0 {
      # Turn on or off the router flag for Neighbor Advertisements
      router no
      # Control how long to wait for a Neighbor Advertisment message before invalidating the entry (milliseconds)
      timeout 500
      # Control how long a valid or invalid entry remains in the cache (milliseconds)
      ttl 30000

      # This is a rule that the target address is to match against. If no netmask
      # is provided, /128 is assumed. You may have several rule sections, and the
      # addresses may or may not overlap.
      rule 2001:db8::/64 {
          static
      }
  }

1 files changed, 1 insertions, 11 deletions

diff --git a/src/conf_mode/nat66.py b/src/conf_mode/nat66.py
index 0ba08aef3..dee1551fe 100755
--- a/src/conf_mode/nat66.py
+++ b/src/conf_mode/nat66.py
@@ -1,6 +1,6 @@
 #!/usr/bin/env python3
 #
-# Copyright (C) 2020-2021 VyOS maintainers and contributors
+# Copyright (C) 2020-2023 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
@@ -36,7 +36,6 @@ airbag.enable()
 k_mod = ['nft_nat', 'nft_chain_nat']
 
 nftables_nat66_config = '/run/nftables_nat66.nft'
-ndppd_config = '/run/ndppd/ndppd.conf'
 
 def get_config(config=None):
     if config:
@@ -101,7 +100,6 @@ def generate(nat):
         nat['first_install'] = True
 
     render(nftables_nat66_config, 'firewall/nftables-nat66.j2', nat, permission=0o755)
-    render(ndppd_config, 'ndppd/ndppd.conf.j2', nat, permission=0o755)
     return None
 
 def apply(nat):
@@ -109,14 +107,6 @@ def apply(nat):
         return None
 
     cmd(f'nft -f {nftables_nat66_config}')
-
-    if 'deleted' in nat or not dict_search('source.rule', nat):
-        cmd('systemctl stop ndppd')
-        if os.path.isfile(ndppd_config):
-            os.unlink(ndppd_config)
-    else:
-        cmd('systemctl restart ndppd')
-
     call_dependents()
 
     return None