Forwarding interesting traffic

We've spent a working day trying to figure how to implement forwarding of selected traffic in netgraph. No result. So ... It took a couple hours to do one one very simple module: fixmac.

Fixmac overwrites destination mac. This is forwarding, actually - one small disadvantage - need to handle MAC of destination router or system manually (unlike with IPFW, which works with arp table, but even IPFW never initiates ARP lookup).

Fixmac has two hooks (in and out) and process all traffic both ways. Everything going in -> out gets it mac replaced, out->in is intact.

Supports one netgraph message: ngctl msg fixmac: setmac 01:02:03:04:05:06, and stats.

Never thought i'll ever need to remember or get any practical use of this (src: wikipedia):

This time it was quite helpful.
most of my workmates failed to guess which goes first - ether addresses or 802.1q header.