A quick and dirty solution can be to use netcat:

nc -l port-number

-l for listening. May need admin privileges for listening on a port number lesser than 1024. Received data will be sent on stdout, so you may need redirection or piping to another command to use the data.

Also, the command should be active before some remote program connect to the port, otherwise the sending program will fail.

For more information, see netcat man page.