Simple port scan
Periodically, I will read something that makes me want to check open ports on this or that server in order to sleep better at night. I use nmap infrequently and always forget how easy it is to quickly run a port scan on a server.
Scan with “fast mode” – only the top 100 most common open ports:
$ nmap -F server.domain.com
Starting Nmap 6.47 ( http://nmap.org ) at 2015-08-27 21:41 CDT
Nmap scan report for server.domain.com (50.51.52.153)
Host is up (0.11s latency).
Not shown: 96 filtered ports
PORT STATE SERVICE
22/tcp open ssh
25/tcp open smtp
80/tcp open http
443/tcp open https
Nmap done: 1 IP address (1 host up) scanned in 3.19 seconds
Additional nmap sites: