Re: simple iptables rules

[Frederik Rousseau <fred@cmelectronics.be>]

Re> adsl router (internal ip 192.168.1.254)
Re> 	-> me (192.168.1.245)
Re> 	-> flatmate (192.168.1.dhcp)
Re> 	-> second flatmate (192.168.1.dhcp)

I guess your ADSL router is on the same network as your first nic as your 
second nic. This is bad.
Use for example 192.168.1.0/24 for nic 1 and 192.168.2.0/24 for nic 2.
Give your ADSL modem an IP from 192.168.1.0/24 and your flatmates an IP from 
192.168.2.0/24.

When this is done, check `sysctl -a|grep forward` and look if your network 
forwarding is set to '1'. If not, change 'ip_forward=no' to 'ip_forward=yes' 
in /etc/network/options.

Then you place some FORWARDing rules in the iptables and maybe you need to 
MASQUERADE the traffic of your flatmates, if the ADSL router doesn't do 
it ...

Re> does this help?

Yes, but more is better :)

Fred
-- 
Frederik Rousseau (fred-at-cmelectronics-dot-be)   http://www.cmelectronics.be
   Is GNU/Linux the future?  Hell, it's the present:
     http://www.dwheeler.com/oss_fs_why.html