How to configure Xchat and IRC server to transfer files?

Question

How do I configure Xchat to send files?

My setup:

hardware router: xxx.xxx.xxx.xxx example.com
       |
Ubuntu Server with IRC server: 192.168.1.2

Local machines: 192.168.1.x

My aim is to allow to send files between the local machines. By now, they are able to talk on the local IRC channel.

• which ports do I need to open on the router?
• what do I need to configure on the server?
• how to configure XChat on the clients?
• how to troubleshoot/debug the problems?

Solution

The method by which files are sent in Xchat, and on IRC in general, is via Direct Client to Client (DCC). A direct connection is established between the two relevant machines and the file is sent. While IRC protocol allows any non-privileged ports to be used, Xchat uses ports 4990 to 5000 for DCC.

If you were sending files to machines on the Internet, since you have network address translation, you would need ports 4990 to 5000 forwarded to the machines doing the DCCs. But since you are transferring files on your LAN, it is not necessary in this case. If all internal routing on your LAN is open (which odds are it is, although I don't know), then the files should transfer without a problem, and without need for port forwarding or anything.

To send a file, I simply right-click a user name within Xchat and send the file. To receive a file, I see in my main console Xchat window (usually) something like "Dennis has offered motd (122 bytes)". I type "/dcc get Dennis motd" and the file is pulled.

The DCC file transfer in Xchat is a little buggy, if your Xchat window crashes during a file send/receive attempt, file a bug at Launchpad. If that happens, your ~/.xsession-errors file would have be dated at or after the crash, and a line near the bottom would mention an xchat failure.