Port 43 Whois Lookup

From the Unix command line:

telnet whois.tld.xxx 43
Enter domain name <ENTER>

Can be done in windows too.

For a lookup program, best one is a python package: pythonwhois

Commands on Ubuntu Linux:
-----------------------------------------------
apt-get install python python-pip
pip install pythonwhois
-----------------------------------------------

Read here: cryto.net/pythonwhois

You need an outgoing connection to port 43. Unless you are using a third-party service (who.is for example)

Not all WHOIS servers are port 43, though most/practically-all are. rwhois.org.za uses port 4321.

You can do it in PHP with the fsockopen() function:

fsockopen("some.whois.server",43,$errno,$errstr,5);

More info from the PHP manual:

http://uk1.php.net/manual/en/function.fsockopen.php

I use the above method. I tried to do it with cURL which I normally like but couldn't get it to work properly with WHOIS servers.