ipmasq + port filtering recipe?

[Luke Scharf <lscharf@ee.vt.edu>]

I've searched http://groups.google.com and and the web for a quick
recipe.  I've also scanned the general documentation, but I haven't
figured out exactly how to do this yet.

I have a machine that's running Debian Potato a web server and an
ipmasq.  The machine has an "internal" and "external" network card.  The
internal network runs on 10.0.0.0/24 and the external network has a
static IP address.

I've apt-get install'd the ipmasq package and the IPMasq functionality
works great.  What I'd like to do now is to use ipchains to do the
following:
1. On the external interface, I would like to only accept traffic from
port 22 and port 80.
2. The internal interface should be wide open - the internal network we
trust the users who are physically in the room not to be malicious.

Can you all point me to a recipe on how to do this?  Is there any
documentation that applies to this specific situation?

Thanks in advance!
-Luke



-- 
Luke Scharf, Jack of Several Trades
http://www.ccm.ece.vt.edu/~lscharf