FreeBSD-based firewall m0n0wall 1.33 brings IPv6 improvements
The latest stable release features a new image type for generic PCs with a serial console and better Realtek driver support. IPv6 improvements include support for LAN IPv6 prefix assignment using DHCP-PD, the addition of an MTU option and interface status page updates, as well as support for syslog destination and Firewall States diagnostics. A number of bugs found in 1.32 have also been addressed.
You don't need to be a genius to debug a pf.conf firewall ruleset, you just need the guts to run tcpdump