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Setting up a "bridge" using Linux with 3 NIC in PC

U

ugh

Platinum Member
Hi all,

First of all, please ignore the lame duck message title. Have no idea how to describe it in one sentence. Anyway, on to the question. I have a DSL connection that I wish to share among my 3 machines. 1 Linux server and 2 desktop machines. I do not have the $$$ to purchase a switch for the time being, and I have an idea which I don't know will work or not.

Instead of using a switch (or a DSL router), I was thinking of installing 3 NICs in the Linux server (1 for the DSL modem and the other 2 for the desktop PCs). Will this setup be difficult to setup? Is this really possible?

TIA.
 
You mean you're trying to set up a PAT firewall.

Take a look at this canned Linux distribution for that purpose: http://www.smoothwall.org/
(that would require a reinstall though)
or go over to http://www.freshmeat.net and do a search on "Linux firewall"

It's not terribly hard to do by hand, but if you're new to it, it would be best to get a distribution or at least a configuration tool already set up for the purpose.
 
I know about NAT, but what's PAT? Actually I was thinking about Smoothwall. But I'm not sure if I can run any extra stuff in it like a full distro. Any ideas?
 
NAT is Network Address Translation. 1:1 mapping.
PAT is Port Address Translation (aka Protocol Address Translation). many:1 mapping. (in Linux, it's called IP Masquerading)

PAT is very often incorrectly called NAT. The thing your SOHO routers do, that's PAT, not NAT.

I'm not sure, but I would expect that Smoothwall is going to make it easy to be a firewall and hard to do server stuff. Contrast with a traditional distribution being easy to do server stuff and hard to be a firewall. The key about a free software system like Linux is that you CAN hack it do do what you want, not just what the people who made the system intended. But if you are planning on using your box as a Linux server also, then you probably are best off using a standard distribution and searching for an iptables-based firewall configuration program (there are several out there).
 
... actually PAT is m:n, and NAT is a simpler special case of PAT, technically speaking. At least in theory NAT is less work because you only have to mess with the IP headers and you can do it statelessly, but the difference between theory and practice means you have to do almost all the work for PAT anyway, which is how we got to full PAT. (NAT was originally intended to solve the renumbering problem, but PAT turns out to be really helpful for address space conservation)
 
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