Which linux-based firewall? [closed]

Solution 1:

PFsense is easier solution for you. you may want to check monowall, ipfire (ipcop with 2.6 kernel) or untangle but all of them except pfsense has no web gui for multiwan setup. in fact most of them is not supporting multiwan solutions.

but pfsense has different options for multiwan. because multiwan is not an easy to setup. it has many restrictions on connection.
here is some sources
http://doc.pfsense.org/index.php/Multi-WAN_Version_1.2.x

(Andrew, this thing is not allowing me to vote up or comment. that's why i wrote as new answer)

Solution 2:

pfSense is what I'm trialling at the moment, based on a similar question I had. It's FreeBSD based but seems to do everything we need (and I think it does everything you want). You can also look at things like Endian Firewall, SmoothWall, eBox Platform, etc.

Solution 3:

Untangle is free and OSS, with premium subscriptions for load balancing and more robust web filtering - http://www.untangle.com - available on 14-day free trials.

Recommended top Content filter by Spiceworks community, too.

Disclaimer: I work for Untangle, so please try it out for yourself, don't take my word for it.