Using SSH banners is not exactly troubleshooting in its purest form (and yes, we are dipping into the subject of hardening). However, as it is often considered to be a good idea that all servers carry some form of legal banner, notice, or security warning that should be displayed to a user before and after the SSH authentication process is started and finished, it is an area we should explore. Troubleshooters do not build systems, but they do fix them and, for this reason, it is something you will be expected to know. Moreover, as this provides an entry into the world of SSH, learning how to develop your very own (and unique) SSH login banners will be a nice place to start.

To display a banner prior to SSH authentication, you should open the following file in your favorite editor:

# nano /etc/issue.net

Now, add the desired message, notice, or security notice as required, but remember, try to keep it short and simple.

For example, you may want to say:

Warning! You are entering a...