$ sudo apt-get install ddclient

PORT FORWARDING ROUTER:

Name: ssh_obscure
Protocol: TCP
Source port: 2121 (or whatever you choose)
Destination IP: (enter the client PC's IP)
Destination Port: 22

$ sudo apt-get install openssh-server

CONFIG
/etc/ssh/sshd_config
     >> Port 2121

$ sudo /etc/init.d/ssh force-reload

$ sudo apt-get install fail2ban

$ nano /etc/fail2ban/jail.local
>>>>>>>>>>
[ssh]
enabled = true
port = ssh   #(or port = 2121)
filter = sshd
logpath = /var/log/auth.log
maxretry = 3
bantime = 600
>>>>>>>>>>>>>>>>>>

$ sudo /etc/init.d/fail2ban force-reload

$ ssh -p 2121 username@daddy.dyndns.xyz

https://chrisjrob.com/2011/04/05/dynamic-dns-and-remote-ssh-and-vnc/