List all listening TCP & UDP connections: netstat -tupl
-t Show TCP connections
-u Show UDP connections
-p Show the program name listening on that port (may require sudo)
-l Show all Listening connections
-n Show numeric values rather than service names
-r Shows the system routing table.
-c <adapter name> Show all connections for the specified adapter
-m Show statistics recorded by the memory management routines
Read the man pages at https://computing.llnl.gov/tutorials/performance_tools/man/netstat.txt for more info.