dhclient exit script for dhcpv6 prefix delegation, used on google fiber with debian 9

dhclient-ipv6

#!/bin/bash

# vim:tw=80:tabstop=2:shiftwidth=2

# Copyright (c) 2012-present, Phil Dibowitz <phil@ipom.com>
#
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#
# You can find the latest version of this at:
#   https://github.com/jaymzh/v6-gw-scripts

# This is a dhclient exit script for dhcpv6 prefix delegation, used on google fiber with debian 9
# This script is a fork of the original at https://github.com/jaymzh/v6-gw-scripts
# Place it in /etc/dhcp/dhclient-exit-hooks.d

INT_IFACE='enp3s0'  # Edit this
EXT_IFACE='enp1s0.2' # Edit this

ipv6_prefix_setup() {
  current_ip=$(/sbin/ip -6 addr show dev ${INT_IFACE} scope global |\
               /usr/bin/awk '/inet6/ {print $2}')
  current_prefix=$(echo ${current_ip} | /bin/sed -e 's@::1/64@::/56@')
  if [ "${current_prefix}" = "${new_ip6_prefix}" ] ; then
    return
  fi

  # Setup the new IP
  new_ip=$(echo ${new_ip6_prefix} | /bin/sed -e 's@::/56@::1/64@g')
  if [ ! -z "${current_ip}" ] ; then
    /bin/ip -6 addr del ${current_ip} dev ${INT_IFACE}
  fi
  /bin/ip link set dev ${INT_IFACE} up
  /bin/ip -6 addr add ${new_ip} dev ${INT_IFACE}

}

if [ "${interface}" != "${EXT_IFACE}" ] ; then
  return
fi

case "${reason}" in
  BOUND6|REBIND6)
    # We will get called twice here - once for the temp address
    # and once for the prefix. We only care about the prefix.
    if [ ! -z "${new_ip6_prefix}" ] ; then
      ipv6_prefix_setup
    fi
    ;;
esac