If you like to change the default welcome message for SSH login for your VPS or dedicated Linux based server, you need to first login in to you server as root via SSH. Then next step you open the file:
/etc/motd
Then you type the security SSH login message you like to appear for all users once they login to your VPS hosting server or dedicated server through SSH.
You may use some SSH login message like this as a start:
This computer system is for authorized users only. All activity is logged and regularly checked by systems personal. Individuals using this system without authority or in excess of their authority are subject to having all their services revoked. Any illegal services run by user or attempts to take down this server or its services will be reported to local law enforcement, and said user will be punished to the full extent of the law. Anyone using this system consents to these terms.
Final step is logout of SSH terminal then log in back to SSH and you should see your new SSH login welcome message for your VPS hosting or dedicated server.