Port Numbers (was Re: use-revolution digest, Vol 1 #398 - 16 msgs)

[Shao Sean]

as per the IANA < http://www.iana.org/ >

"The System (Well-Known) Ports are those from 0 through 1023"..
these are usually blocked by your ISP so you can not run those types of servers.. some ISPs only block the specific ports (ie. 80 for HTTP).. these ports are the ones all the really old and established internet protocols run on (as mentioned previously: 80 for HTTP; 21 FTP; 23 Telnet; 25 SMTP; 110 POP3)

"The User (Registered) Ports are those from 1024 through 49151"
these are ports that are registered to private internet applications, even though some of the 'well-known' protocols use these (6667 IRC)..

"The Dynamic and/or Private Ports are those from 49152 through 65535"
use these ones for your application if it's to be used inhouse or of limited use in the outside world, or you just don't care to register them..

http://www.iana.org/assignments/port-numbers
a rather lengthy and geeky read of all the assigned port numbers (yes, i'm almost done ;-)