On our IPFilter 4.1.17 (Solaris 10/x64) firewall, I've got the following config to enable OpenVPN.
There's definitely no problems with load and it routinely transfers hundreds of megabytes per session without issue: ipf.conf pass in quick on <interface> proto udp from any to a.b.c.d port = 1194 keep state and ipnat.conf rdr <interface> w.x.y.z port 1194 -> a.b.c.d port 1194 udp Hope this helps.
