4.5.4. openssh

openssh (Port 22) encrypts communication sessions over a computer network using the SSH protocol.

Banner grabbing with netcat will give you the version back:

$ nc -v 10.0.0.65 22
Ncat: Version 6.25 ( http://nmap.org/ncat )
Ncat: Connected to 10.0.0.65:22.
SSH-2.0-OpenSSH_6.1

There are two other ways to retrieve the version with nmap. The first is

$ nmap -sV -p 22 10.0.0.65
[...]
Host is up (0.00053s latency).
PORT   STATE SERVICE VERSION
22/tcp open  ssh     OpenSSH 6.1 (protocol 2.0)

The second is

$ nmap -sV -p 22 --script=banner 10.0.0.65
[...]
Host is up (0.00061s latency).
PORT   STATE SERVICE VERSION
22/tcp open  ssh     OpenSSH 6.1 (protocol 2.0)
|_banner: SSH-2.0-OpenSSH_6.1