Allowed Port Range for TCP

Question

I am trying to generate a random port number for a TCP connection. From : http://en.wikipedia.org/wiki/List_of_TCP_and_UDP_port_numbers I know that the range of ports is from 1024 to 49151 are not reserved, but some of them are UDP only, how can I generate only valid TCP port numbers?

Answer 1

If you bind to port 0, the OS will select a valid, not-in-use port.

If you need random as opposed to arbitrary, anything from 49152–65535 should be safe for automatic use like this, so just select a random number within that range. (you may have to retry if that port turns out to be in use, however.)