If you want to stick with perl, I would suggest to read chromatic's Modern Perl book.

http://onyxneon.com/books/mode...

Model A cost $25 and model B cost $35

What does licensing have anything to do with promoting standard? If the original TCP/IP stack was GPLed, people will still able to write the code from scratch using the TCP/IP standard.
Look at Linux, does it use the BSD'ed TCP/IP stack. Nope, it was written from scratch. It does not need to copy the BSD'ed TCP/IP stack. If Linux can do it, then other people should be able to do the same (i.e.: if TCP/IP stack was GPL'ed, people still can create TCP/IP stack from scratch using whatever license they want, it's a bloody standard).