identd and irc servers

[warlord at MIT.EDU (Derek Atkins)]

Scott Lanning <slanning at buphy.bu.edu> writes:

> On 28 Nov 1999 18:25:47 -0000, subb3 at ibm.net wrote:
> >Most of the irc servers try to resolve the client identd. Some
> >of them do not even allow a connection. How can I fix this problem?
> >Where is identd invoked from? Are there any security issues with it?
> 
> man identd :)
> It can be invoked manually or through inetd.
> I never used it and don't know security issues, but I'm sure there
> are some.

identd is run from inetd, usually.  The purpose of identd is for a
remote machine to be able to ask who is actually using a service.  In
other words, IRC want's to know your "real" username.  Basically, it's
a privacy violation.  Luckily, there is absolutely no security in
identd, so you can write your own.  I recommend this source code:

#include <stdio.h>

#define NAME "me"

main(argc,argv)
  int argc;
  char *argv[];
{
	int lport, fport;

	/* Get the local/foreign port pair from the luser */
	if (scanf("%d , %d", &lport, &fport) != 2) {
		printf("%d, %d: ERROR: UNKNOWN-ERROR\r\n", lport, fport);
		exit(1);
	}

	printf("%d, %d: USERID: UNIX: %s\r\n", lport, fport, NAME);
	exit(0);
}


-- 
       Derek Atkins, SB '93 MIT EE, SM '95 MIT Media Laboratory
       Member, MIT Student Information Processing Board  (SIPB)
       URL: http://web.mit.edu/warlord/      PP-ASEL      N1NWH
       warlord at MIT.EDU                        PGP key available
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