There are various places that discussion relating to Amateur Radio and Linux take place. They take place in the comp.os.linux.* newsgroups, they also take place on the linux-hams list on vger.kernel.org. Other places where they are held include the tcp-group mailing list at ucsd.edu (the home of amateur radio TCP/IP discussions), and you might also try the #linpeople channel on the linuxnet irc network.
To join the Linux linux-hams channel on the mail list server, send mail to email@example.com with the line subscribe linux-hams in the message body. The subject line is ignored.
The linux-hams mailing list is archived at: http://hes.iki.fi/archive/linux-hams/ and http://web.gnu.walfield.org/mail-archive/linux-hams. Please use the archives when you are first starting, because many common questions are answered there.
To join the tcp-group send mail to firstname.lastname@example.org with the line subscribe tcp-group in the body of the text.
Please remember that the tcp-group is primarily for discussion of the use of advanced protocols, of which TCP/IP is one, in Amateur Radio. Linux specific questions should not ordinarily go there.