Oidentd
oidentd is a very small daemon which is designed to reply to incoming requests for a username. The practical difference is that you show up on IRC as yourname instead of ~yourname. It serves on port 113 aka "IDENT".
How to get oidentd working behind a firewall[edit]
A common problem with IPv4 is that most Internet service providers only give out you IP address and a firewall that is used to connect computers on your local area network. This causes problems when computers on your LAN needs to reply to outside connections. You can use oidentd to make your LAN boxes respond correctly to identity request.
Requirements: Port 113 must be forwarded to a computer where you can run oidentd.. This can be done by running oidentd on the server and oidentd with the --proxy= option on the client.
Use this oidentd (/etc/conf.d/oidentd) configuration on the gateway / server and make sure it's firewall allows connections to port 113:
USER="nobody" GROUP="nobody" OPTIONS="-f -m"
The clients on your LAN must also be running oidentd using a configuration like this:
USER="nobody" GROUP="nobody" OPTIONS="-q --proxy=192.168.0.1"
Replace 192.168.0.1 with the local IP of the machine you use as oidentd server.
Using nobody as a user and group is just a suggestion, just make sure you do not run it as root.
Gentoo users can start oidentd with /etc/init.d/oidentd start, run rc-update add oidentd default to make it start at boot.
On systemd machines it's started with systemd start oidentd.service
