How to reconnect to Ethernet interface on Linux computer?

best starting kit for a dual-lan linux gateway machine

• I use a second computer set up with Ubuntu server as a gateway/firewall (NAT box) and email server. It has finally died. I'd like to replace it with a new machine. I checked on newegg a bit, but I'm not a hardware geek so I'd like to query the hivemind for their ideas. Specifics: 1) The new machine can be fairly bare-bones, I run it headless 99.9% of the time and it mostly just collects email and passes packets. This means I don't care very much about memory, CPU, or graphics processing. 2) Ideally a dual-LAN motherboard, but I'll buy a five dollar PCI card to add the second ethernet interface if I have to. Only one interface needs to be gigabit ethernet. 3) Ideally x86, but AMD is fine if the price is significantly lower. 4) Has a RAID controller (RAID 1 specifically, but I've never heard of one that didn't support that). I want to add a pair of drives (already have them) as backup storage, in RAID 1. 5) Price is the main factor subject to the above, but I'm willing to pay a teeny bit more for something that will last longer (i.e., something with better-quality components). Maximum ~$300, ideally less. I've assembled systems from components before, so I can put anything together that needs be.

• Answer:

  The http://diynas.com/ site might have some helpful information about choosing hardware. Given your price/power requirements, have you considered small embedded linux systems such as the Raspberry Pi and Beaglebone? With an http://www.newegg.com/RAID-Enclosure-Subsystems/SubCategory/ID-509?Order=PRICE, they might make more sense than building a full-fledged system.