I recently moved into a building with a shared internet connection where I can only connect one computer directly into an Ethernet port in the wall, and not a router. What I'd like to do is connect a computer with two network cards, plug the internet into eth1, and connect my router to eth0. I'd like the other computers connected to the router to be able to both access the Internet and share files with each other, so that I have the same functionality I did before when I had a cable modem and all my computers connected to the router.

I'm using Crunchbang, based on Debian 7.1, on the computer with the two network cards. I've been using Linux for a long time and I'm not afraid of using a command line or editing config files but I've never needed a network configuration that hasn't "just worked" without extra setup so I'm not really sure where to start.

Edit: If it matters, I generally route all my traffic through an offshore VPN to stop Big Brother from watching my Internet traffic, except when I occasionally disable it to use websites that treat visitors from outside the US differently.

i would consider http://www.ipfire.org/ its a hardware firewall setup. the wall jack should treat it as a computer instead of a "router".

then with the 2nd NIC you could just run the LAN side NIC into a switch and be set. IPFire will handle your internal DNS and DHCP if you dont wish to run static IPs.

I installed IPFire on an old netbook I wasn't using and this works great, except that my VPN is being blocked by IPFire. I can connect to the VPN fine, but once I'm connected, I can't access the Internet. This happens whether I'm using OpenVPN or PPTP, both of which my VPN provider supports. I've done some searching but all I can find are instructions for how to set up IPFire as a VPN client which isn't really what I'm looking for - I'd prefer to have individual computers connect to and disconnect from the VPN as needed. Any idea how I can reconfigure IPFire to fix this? I realize this question might be better asked on the IPFire forums but I thought you might know.

sadly Im an IPCop user, and have not upgraded to IPFire yet. There should be a way to allow for VPN pass through. I'd hit up either their forums or their mailing list.

Im glad the IPFire box is working for the LAN though. Ive been an IPCop user since 1998 or so. If its not broke im not going to fix it. I will upgrade to IPFire when my ISP starts rolling out IPv6 as IPCop does not handle IPv6.