What Network Services are Running

$ netstat -tanup

     or if you just want tcp services
 
          $ netstat -tanp

     or

          $ netstat -ap|grep LISTEN|less

     This can be helpful to determine the services running.

     Need stats on dropped UDP packets?

          $ netstat -s -u

     or TCP

          $ netstat -s -t

     or summary of everything

          $ netstat -s

     or looking for error rates on the interface?

          $ netstat -i

     Listening interfaces?

          $ netstat -l