portnumbers

[Da-Nuka]

If I have got it right, I can use any portnumber for my program?
(In theory?)

Like if im making a chat server/client,
I can actually make my chat clients/servers speak to each other through port 80?

Or do I have to chose a "unserserved" portnumber?

[bithub]

Yes, you can bind to any port that is not already in use, and is less than 65356. To bind to a port under 1024 requires root access on most *nix setups though.

[kuphryn]

You can potentially bind to any port you want. The issue arises when it is a common port used for something else. Then other apps and services may not function correctly.

Kuphryn

[iain]

Ports are reverved for good reasons, you should not really use ports below 1024.
Common ports: (invalid link removed)

[Xipher]

You can use any port EXCEPT 0 (commonly used by OS's to give you a random port actually, and is considered reserved by IANA). As it was mentioned most *nix variants protect ports 1024 and below. I would suggest using an unreserved port any ways though, as you don't have to worry about steping on any toes (so to speak), incase it is being used.

Iain, I don't see any ports listed on that site, a beter choice would to just go to the source (IANA) any how, as they keep the up to date list on the web. This can be found at http://www.iana.org/assignments/port-numbers



Oh, and some trivia, can you guess who got the port 666 assigned to them?

[iain]

sorry, wrong link!