Network problems

[Timothy Murphy]

Reindl Harald wrote:

>> I've found from this that I don't really understand how networking works,
>> and I'm writing now to ask for some help with this.

> google for POSTROUTING / MASQUERADE (iptables)

Thanks for your response;
but I think I do understand what IP masquerading is.

Just to repeat the gist of my question (slightly re-worded):
-------------------------------
I have the lines
  #INTERFACE SOURCE ADDRESS PROTO PORT(S) IPSEC MARK
  eth0       eth1
in /etc/shorewall/masq on my server.
-------------------------------
My question is: what exactly is the effect of this?
Does IP masquerading by default only apply 
to the firewall server to modem interface (eth0 in my case)?
And does the above line mean that it will also be applied
to packets reaching the firewall server on the eth1 LAN?

I couldn't find a clear account of the effect of the line
anywhere in the shorewall documentation.

-- 
Timothy Murphy  
e-mail: gayleard /at/ eircom.net
tel: +353-86-2336090, +353-1-2842366
s-mail: School of Mathematics, Trinity College Dublin