OpenVPN, IPv6 and a FreeBSD firewall

02 Nov 2006 • 1 min read

OK, so I run OpenVPN to secure everything. Which is good :)I also run IPv6 just for kicks, which is also good :)I'm starting to love FreeBSD more and more, which is always good :)So what's the bad part? Well, add any any firewall into the above mix (ipfw, pf - ipf didn't compile) and IPv6 connections just hang. After weeks of banging my head, scouring FreeBSD bug reports and firewall setups I was getting nowhere 😦 Infact I was just about to file a FreeBSD bug report when The_Paya mentioned that mss maybe too high. So lo and behold I experimented and he was right!After trying out many settings, using the OpenVPN setting of tun-mtu 1420 seemed to work the best.There's also this patch for an old beta, but I've not played with that yet.