Many IRC servers expect to be able to query an ident server on computers that connect to them. This is obviously a problem when connecting from behind a firewall.
Many years ago, the Coyote Linux distribution had an option to install oidentd. It is a NAT-aware ident server that is capable of forwarding ident requests to the machine that opened the connection being queried. That feature disappeared from Coyote Linux sometime during 2.x development, probably because it opens a hole in the firewall (at port 113).
I've created an add on for BrazilFW from the oidentd-2.0.8 source. The source can be found at http://ojnk.sourceforge.net/. I'm currently running this add on on my personal BrazilFW, version 2.28.
If anyone is interested, I'd be happy to make this add on available to the BrazilFW community.