I'm setting up the more restrictive filtering "deny all but those explicitly
allowed", and I've discovered that DHCP is failing to function with the
filters enabled.

With the restrictive filters loaded, new workstations plugged into the
intranet are unable to contact the DHCP server and receive an IP address and
the network mask.

If I disable the packet forwarding filters and reinitialize, I am able to
renew the workstation and instantly get the address/netmask.

How am I to allow DHCP to function on the intranet, and have it cooperate
with the packet filters? There is no predefined filter for DHCP...