Re: Rewrite MAC-adr on outgoing packages?

[Jörn Engel <joern@wohnheim.fh-wedel.de>]

Hi!

> What I want to do is simple:

At first sight, yes. :)

> All packeges leaving my eth0 interface shuld have the MAC-
> adress of my eth0-card. Regardles if they is orginating att
> another machine and only routed trhu this machine (who is
> a gateway).
> [...]

If you want to change the MAC address of a package without repackaging it,
you will have to write the patch yourself. And it is not trivial.
You have to change the MAC address of outgoing frames (trivial) and of
incoming ones (tough). So how do you know where to send the incoming packets
from you cablemodem. The IP might be a key, but an IP package might be split
up into several ethernet frames. So you will also need a table of fragmented
packages.
If you are willing to do that, you might find interesting code in the
bridging and NAT parts of the kernel. If not, there are easier and more
secure ways to do the job:
Set you linux box up as a router, thus repackaging all IP packets. With
squid and danted (socks) properly configured, the other boxes can access the
internet and you have a single firewall for every box.

-- 
``Plan to throw one away; you will, anyhow.'' 
(Fred Brooks, ``The Mythical Man-Month'', Chapter 11)