http://superuser.com/a/529844 (net-stat is deprecated) http://www.cyberciti.biz/faq/how-do-i-find-out-what-ports-are-listeningopen-on-my-linuxfreebsd-server/
# nmap -sS -O 127.0.0.1 # lsof -i # netstat -lptu # netstat -tulpn