The login banner is what comes up after you’ve entered your username (unless the client sends it automatically, then it’s the first thing you see), it can contain warnings, welcoming messages or ASCII art.
Okay, how can I change mine? To edit/change/enable the login banner you need root access to the system. open up /etc/ssh/sshd_config in your favorite text editor and find the line that says “Banner …” in some cases this line is commented out, make sure to uncomment it.
I recommend changing the file it points to, I usually put mine in /etc/ssh/banner(Banner /etc/ssh/banner) this is a plain text file, so you can pretty much enter anything you want, but be aware that not everyone runs their ssh client in full-screen. after you’ve changed the banner file, you will need to restart your SSH server, in debian-based systems this can be done with /etc/init.d/ssh restart don’t worry, users will not be kicked out.
Click here to download he Ascii of my Hypno Toad in the above image.