Network Port mumbo-jumbo (terminologies)

[rizboy]

Hey, everyone! I'm planning to use windows XP firewall, since my comp is kinda strange and norton stuff don't really work on my computer.

well anywho. i am behind a router, and i was able to open some range of port for few file sharing programs.

but what are "internal" and "external" ports? and what are TCP and UDP stuff? and i can't seems to have my Outlook Express 6 to check my email (POP3) and there was some sort of POP3 option on my router setting, but i'm just so confused :(

i just want to use my regular winXP firewall, and i want my POP3 mail, msn messenger, bit-torrent, and access to FTP sites to work.

i've just gone hacker-paranoid recently, i thought it wasn't possible to get hacker behind a router, but just incase ;)

any help will be appreciated!

[rizboy]

if this topic was already posted, can someone post a link to that thread? thaaanks!

[gtaylor]

but what are "internal" and "external" ports?

Internal ports are those on your computer, not like USB, but software channels through which data can flow. There are thousands, but a few are always used for some things like pop3 or smtp. External ports are those that another computer would try to connect to on your computer. Remote ports are those of another computer. e.g. when you send mail (SMTP), your computer opens internal port 25. This then requests opening of external port 25. When a success code is returned, the remote port 25 on the smtp server is requested to be openend. When successful, data can pass between the computers. The ports are then closed.

and what are TCP and UDP stuff?

TCP = Transport Control Protocol (generally it is TCP/IP, the IP being Internet Protocol). It's basically a language that computers talk to each other in.
UDP = User Datagram Protocol, another language for computers to talk to each other.

and i can't seems to have my Outlook Express 6 to check my email (POP3) and there was some sort of POP3 option on my router setting, but i'm just so confused

When did it go wrong? What changed between the last time it worked, and now when it doesn't?

i've just gone hacker-paranoid recently, i thought it wasn't possible to get hacker behind a router, but just incase

You're right to be paranoid. In theory, if the router has a firewall or NAT, it should be quite difficult for the hackers to get in, but certainly not impossible. My advise is to always run a firewall if you use the internet a lot, or have a broadband connection. Theoretically, you should be able to close all external ports. When you need to do something, your computer will request opening the port for the data flow and response. It should close it again after it has recieved the response, keeping it secure. I obviously can't say what your equipment will do, but that is a quick guide on how it is really supposed to work.

Hope this helps a little bit.

[tantone]

and what are TCP and UDP stuff?
TCP is connection-oriented
UDP is not

Check THIS out (http://compnetworking.about.com/cs/protocolstcpudp/)