Quick question for enabling NAT in LTSP (or edubuntu) - iptables details

[Gavin McCullagh]

Hi,

On Fri, 14 Aug 2009, Patrick McKnight wrote:

> While writing my script, I noticed a difference between the HOWTO specs
> and my interfaces file.  I have my LTSP network on eth1 and so I used up
> iptables-restore < /etc/ltsp/nat for eth1 and NOT eth0 as specified in
> the HOWTO.  That got me thinking.  Is eth0 the proper interface to
> restore the iptables setting or is eth1?  

https://help.ubuntu.com/community/UbuntuLTSP/ThinClientHowtoNAT

What it actually says is:
 
 "add the extra line 'up iptables-restore < /etc/ltsp/nat' to the bottom of
  the eth0 (or whichever is your LTSP interface) stanza of
  /etc/network/interfaces "

so it does say that you should put it against the interface which LTSP runs
on.

> If it matters then I am confused.  My eth0 is my NIC that goes to the
> internet; eth1 is my LTSP NIC.  Can anyone help clear up my confusion if
> I am truly confused?

I must say I didn't ever check if the order was important but imagined it
likely would be (hence the statement).  If you try to load a bunch of
iptables rules which relate to interfaces which are not yet up you may find
those rules fail to load.  I'm not sure, but it sounds plausible.

Gavin