/me enters friendly-newb-mode
The use of an ip is to identify computers while connecting to other computers, kind of like a numerical name given to your computer that other computers can identify you as. Each is individully unique, given to your machine from your isp, as you probably already know. IP isn't a very complicated thing to understand, in my opinion, TCP, on the other hand, is a bit more complicated. If you're really interested about this sort of stuff then you probably already know from reading tuts that tcp has four layers: 1: Network Access Layer; 2: Internet Layer; 3: Transport Layer; and 4: Application Layer. ... just food for thought.
http://www.good-stuff.co.uk/useful/portfull.html
This is a pretty good tcp/udp port list. It will tell you what ports are used for what, if you don't already know.
You can't get this kind of knowledge just anywhere [alien]

What do gangs have anything to do with ip addresses and open ports? ... just curious.
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=~ s/boredom/ studies/g