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I have an old Dell Dimension with two ethernet cards, and I need to turn it into a firewall. I've tried FireStarter and IPCop, but I don't think I'm setting them up right.

Here's the setup that I'm trying to accomplish: I need to have one ethernet card plugged directly into the modem, and the other ethernet card plugged into a 16-port switch/hub.

Part of the problem is that I've never done this before and despite hours of Googling, I'm still not sure where to start.

I don't need anything fancy or endlessly configurable - I just need some basic protection that I can tweak out later. The bottom line is that it's 10:45p, everyone else left the office at 5p, and I'm still trying to get this taken care of.

Thanks in advance for any help.

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Must head to bed — early morning tomorrow. But this pointer may help: ebtables.sourceforge.net – mattdm Mar 15 '11 at 2:54
I'll look into this - thanks. – kivetros Mar 15 '11 at 3:04
I've been running an old Compaq small-form-factor desktop with a Pentium-II 400 MHz processor for about 10 years. I use Fedora with a simple set of iptables rules. The nice thing about that system is it has no fan so it's very quiet, and 400MHz is plenty for a firewall serving only 4 internal systems :-) – Ex Umbris Mar 15 '11 at 5:47
up vote 2 down vote accepted

for sheer ease of use, I can recommend Smoothwall. I used it many years ago, and it was great then. Just install it following the prompts, and you're done. Of course, you can tweak it and fiddle with it if you want to, but you probably won't need to unless you have unusual requirements. It's very good. :)

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smoothwall is a fine choice - simple, lightweight and secure. You can run it easily off a USB key if necessary, too. – simon Mar 15 '11 at 5:36
It worked perfectly. Thank you so much! – kivetros Mar 15 '11 at 22:20

Basic routing:

echo 1 | sudo tee /proc/sys/net/ipv4/ip_forward

You'll probably want an iptables rule in place :

sudo iptables -t nat -A POSTROUTING -o other_ethernet_card -j MASQUERADE

For the rest, I'll refer you to a Server Fault question on the same topic that I answered.

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Great answer on Server Fault. I've decided to use Smoothwall for now; however, I have bookmarked your answer on Server Fault for if and when I need to get my hands dirty with manual configuration. Thanks for your help. – kivetros Mar 15 '11 at 22:22

I'm using IPCop at home just like you describes it. It is not really that updated, but it is stable and does it's work well.

  • Make sure that he recognise the hardware, the two network cards.
  • Red interface should be the one with the WAN / modem
  • Green interface is your home LAN.
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+1 - for pointing out the Red and Green. This is important :-) – Rory Alsop Mar 15 '11 at 21:36

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