It's only a 3 port system though.
I'm with you about the GPL though. It's my biggest complaint about it. Apart from the proprietary hardware (which OK, I guess I can forgive it), they definitely seem to be playing it pretty loose with the terms of the GPL.
Pf is indeed nice and it'd be cool to run OpenBSD on it. That said, as I mentioned I really like their configuration tools and they make iptables actually quite easy to configure.
Your best bet for a BSD router is probably to pick up a cheapish computer and put in one of the Intel or HP quad-port ethernet cards and then plug into a dumb switch. They can be had for surprisingly reasonable prices, I saw some on Amazon for ~$80 (the quad-port cards, that is).
[0]: http://www.maxxwave.com/solutions/security/routermaxx-6-port...
http://www.mikrotik.com/downloadterms.html
I mean, sure, asking for 45 USD for a CD with the source is technically complying with the GPL -- but it does seem a bit strange in this day and age. Not to mention that for the source code to be useful, one would hope one could build a working routerOS image from it -- and it doesn't appear that the CD will enable a user to build a running image -- and therefore not facilitate changing the product.
But apart from that, my first thought was -- can this thing run BSD -- because pf is quite a bit friendlier than iptables (even if the latter has gotten a lot better lately).
Does anyone know if there are any recommended alternatives to soekris for running a bsd switch/router (preferably running at ~gigabit speeds) ?