dch-gw: Allow outbound DHCP

Connection Tracking does not work for DHCP messages, since many are
broadcast. As such, the firewall must explicitly allow datagrams
destined for the DHCP client port.

group_vars/dch-gw/dch-network.yml

@@ -100,6 +100,8 @@ allow_outgoing:
   port: dhcpv6-server
 - protocol: udp
   port: bootps
+- protocol: udp
+  port: bootpc
 - protocol: tcp
   port: https
 - protocol: tcp