The Secure Shell (SSH) by default uses port 22. Leaving it as port 22 does not make your system insecure, nor will changing the port provide a significant increase in security. However, we do advise you to change the default SSH port, this will stop many automated attacks and a bit harder for other people to guess which port SSH is listening on. In other words, a little security though obscurity.
As root, use a text editor (eg. nano) to edit the sshd configuration file.
# nano /etc/ssh/sshd_configStep 2
# What ports, IPs and protocols we listen for Port 50683(Dynamic and/or Private Ports are those from 49152 through 65535 and can be used. Though nothing is stopping you from using reserved port numbers, our suggestion may help avoid technical issues with port allocation in the future.)
# /etc/init.d/ssh restart
ssh firstname.lastname@example.org -p 50683