Oct 032008
The lsof command can display all open files in Linux. With some filtering you can use it to show all open/utilized ports as well.
lsof -i TCP:443
This command will list all processes, their pids, and user under which the process is running, that are utilizing port 443.
To list all TCP ports, one could use
lsof -i TCP
Type lsof –help for more options.