# nmap -O 192.168.84.10         # (for example)

Example output:

Starting Nmap 6.47 ( http://nmap.org ) at 2015-09-24 22:30 CEST
Nmap scan report for 192.168.84.10
Host is up (0.000078s latency).
Not shown: 997 closed ports
PORT    STATE SERVICE
25/tcp  open  http
80/tcp  open  http
111/tcp open  rpcbind
443/tcp open  https
Device type: general purpose
Running: Linux 3.X
OS CPE: cpe:/o:linux:linux_kernel:3
OS details: Linux 3.7 - 3.15
Network Distance: 0 hops

OS detection performed. Please report any incorrect results at http://nmap.org/submit/ .
Nmap done: 1 IP address (1 host up) scanned in 92.05 seconds