(there may be many wrong saings in here, please correct me) How does mIrc get IRC running? Well it sets up "identd" to respond to a http request "AUTH" by entering something like a "username" in the connect dialog window. The result is that mIrc answers an "AUTH" request with: "whatever_entered_in_the_dialog_window@whatever_you_stated_in_hostname" ie. it sends a responce with what you said you are in the network configuration's "hostname" and the string you put in mIrc's "identd" reply.
Short answer: They don't do this! Usually in /etc/inetd.conf (the file that handles what the system should do when getting asked something over the network) "pidentd" is the program that answers to "AUTH" requests.
It does the same as mIrc does... almost... pidentd replies your hostname and the username but if you log on as a user that has a file called ".noident" in her/his homedir (/root or /home/whatever) then it will reply "UNKNOWN" and since most IRC servers doesn't accept "UNKNOWN" as username they won't let you in... so how do we get into IRC in Linux? Easy, if you can get into IRC from windows you configure you hostname to the same as in windows... (in slakware you use "netconfig" in redhat you use the "network" thingie in the controlpannel) and then you create a user with the same name as you entered in identd in mIrc. Then you log on as that user and start irc, and you will get in (IF YOU GOT IN FROM WINDOWS)
Well I got K-Lined on servers that let me in when i used windows 95 and mIrc, I decided to find out what the problem was, from the #Linux channel i learned about "AUTH" and "pident" then i read the pident man page, there it stated that if inetd.conf called for "pidentd" with a special parameter it didn't reply the correct username if a "~/.noident" is present. And the rest I just figured out by experience. I think that pidentd doesn't actually reply user@host it just replies the user part... But i dont know...
I'd like to know if there is another identd client that doesn't reply the correct username, coz i'd like to logon as "orvar" and have it reply something else, like "korvar" for an example. ie. more like mIrc does...