Add local IRC server post.

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+Tonight I've been looking into ways to set up a local chat system for
+students in one of my courses.  My initial thought was to use the
+NetKit `talk` at `talkd` programs, but I couldn't find an active
+homepage.  Maybe they are so mature that noone needs to touch the
+code, but I expect they are actually just quietly dying in the corners
+of assorted harddrives, without any users to love them.
+
+Since part of the goal of my course is to get the students up to speed
+on common open source development tools, my next thought was to go
+with a local [IRC][] server.  I know that there many wonderful public
+IRC servers (e.g. [freenode][]), but why use a free service when you
+can run the service locally?  Anyhow, here's my setup.
+
+Local IRC server
+================
+
+There seem to be a number of these out there.  I chose [ngIRCd][],
+because it's packaged for Gentoo (`net-irc/ngircd`), and it seems to
+be both cleanly coded and actively maintained (in [[Git]] ☺).
+Installation was a simple:
+
+    # emerge -av ngircd
+    # emacs /etc/ngircd/ngircd.conf
+               # cat /etc/ngircd/ngircd.conf
+               [Global]
+        Name = irc.example.com
+        AdminInfo1 = John Doe
+        AdminInfo2 = 123 Street Rd.
+        AdminEMail = jdoe@example.com
+        Info = bla bla bla
+        ServerGID = nogroup
+        ServerUID = ngircd
+               [Options]
+        PAM = no
+               # /etc/init.d/ngircd restart
+
+I didn't add `ngircd` to the default runlevel.  I'll just start it by
+hand whenever I want to use it.
+
+Local connections
+=================
+
+Using the excellent [irssi][] client (`net-irc/irssi` on Gentoo):
+
+    $ irssi -c localhost
+
+When you specify a server on the command line with `-c server`,
+`irssi` won't connect to any other servers for which you've configured
+automatic connection.  In my case, this is what I want.
+
+Exposing the IRC server on a remote host
+========================================
+
+Alright, I've got an IRC server running on my laptop, but I'm behind a
+firewall.  I can expose my IRC server to the students by forwarding
+the IRC port to our department server, where the students all have
+shell accounts.
+
+    $ ssh -R localhost:6667:localhost:6667 physics.uni.edu
+
+If someone else is already using port 6667 on the department server,
+it's easy to use another one:
+
+    $ ssh -R localhost:6668:localhost:6667 physics.uni.edu
+
+Students can then connect by [[SSHing|SSH]] into the department server
+and running `irssi` there:
+
+    student@home $ ssh physics.uni.edu
+    student@physics $ irssi -c localhost -p 6668
+
+And that's all there is too it!  An easy way to introduce people to a
+popular tool.
+
+[IRC]: http://en.wikipedia.org/wiki/Internet_Relay_Chat
+[freenode]: http://freenode.net/
+[ngIRCd]: http://ngircd.barton.de/
+[irssi]: http://irssi.org/
+
+[[!tag tags/web]]
+[[!tag tags/tools]]