The Unity IRC channel is #unity3d on freenode.
The server name is irc.freenode.net and the channel name is #unity3d.
If you are new to IRC, you will need an IRC client. Here are some free Mac friendly ones:
Because it's stable, economical in terms of resources, and provides moderation if needed.
Firewall and Router Settings
You may need to open some or all of these ports on your firewall, or set up port forwarding on your router, to get IRC to work:
- 6665-6669 (may or may not be necessary, outgoing only I believe)
- If you want to use DCC to transfer files, open 32768-32788 too.
- Finally, you can speed up your initial connection to freenode by opening the Ident port, 113.
When you connect, freenode runs a port-scan on your machine to make sure you're not running an open proxy which could threaten their network. This is harmless, but it can make weird things appear in your access logs. If you prevent them from doing the port scan (by blocking their IP, for example), they may block you in return, so it's best to tolerate their scanning.
If you need help connecting, there is a thread on the Unity forum about IRC here.