NMAP

Scan machine for open ports (simple)

To simply scan an ip address for open ports with nmap, all you have to do is type the command below in your terminal:

nmap ip_address

and you will get an answer like this from nmap:

Starting Nmap 5.21 ( http://nmap.org ) at 2011-12-22 03:21 PST
Nmap scan report for x.x.x.x
Host is up (0.026s latency).
Not shown: 995 filtered ports
PORT     STATE SERVICE
139/tcp  open  netbios-ssn
443/tcp  open  https
445/tcp  open  microsoft-ds
912/tcp  open  unknown
3389/tcp open  ms-term-serv

Nmap done: 1 IP address (1 host up) scanned in 47.62 seconds