Problem statement:
-----------------

The task is to create customized Ident server specified in RFC 1413.

Instead of standard RFC 1413 reply, the username that the program should
reply with depends on the command line parameters passed when the server started. 
The operating system returned should always be "UNIX". The reply type must be chosen
by specifying one of the following command-line parameters:

* random
  Replies with the username of a randomly-chosen Unix user on the
  host running your program.

* uid
  Replies with the username of the user whose UID is equal to the
  "client port" parameter specified by the ident client. If there is no
  user matching the requested UID, the program should reply with an RFC
  1413 compliant "NO-USER" error.

* always <name>
  Always replies with the specified name.

The program should format the reply exactly as specified in RFC 1413,
however the username returned should be as specified above. Do not
need to determine the owner of the port specified by the client.
If the program is run with no parameters, it should default to
"random". If an unknown parameter is specified, the -always
parameter lacks a "name", or more than one of the above parameters are
specified, the program should exit with an error.

The program should have:
* Accepts and services multiple concurrent connections.

* Performs basic validation of the client's request. No need to
  follow the RFC exactly, but implement the validation procedures you
  feel are necessary. If the client sends you an invalid request, you
  must disconnect the client (and only that client) immediately without
  sending a reply.


Requirements:
------------
To run this program you need linux with perl installed on it.
Following external perl libraries should be installed:
Getopt::Long
Log::Log4perl
IPC::Shareable

This program is using port 113 as listening port.


How to start:
------------
To start the daemon:
$ sudo ./identd.pl

By default ident server will start in 'random' mode as specified in problem statement.
You can start it in 'always' mode as below:
$ sudo ./identd.pl --always john

To stop the daemon:
$ sudo ./identd.pl --kill

To see the help menu:
$ sude ./identd.pl --help

You can see the logs in /var/log/identd.log. The logfile is useful to understand what is happening with the daemon.


Verify server responses:
-----------------------
You can do verifications by connecting to server like:
$ telnet localhost 113
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
652, 232
652, 232 : USERID : UNIX : nscd
Connection closed by foreign host.


Author:
------
Anand Modh
[email protected]