I have often suffered this painful thing.When I start a service but the destination port is always used.So I should list all open ports and kill the occupied application.
So This is a short tip for how to list open ports on Linux
Note sometimes you should grant the command for a enough access.
For a better understanding,please
or navigate to http://linux.about.com/od/commands/l/blcmdl8_netstat.htm
For Mac Users