Information
The Banner parameter specifies a file whose contents must be sent to the remote user before authentication is permitted. By default, no banner is displayed.
Rationale:
Banners are used to warn connecting users of the particular site's policy regarding connection. Presenting a warning message prior to the normal user login may assist the prosecution of trespassers on the computer system.
Solution
Edit the /etc/ssh/sshd_config file to set the parameter above any Include entries as follows:
Banner /etc/issue.net
Note: First occurrence of a option takes precedence, Match set statements withstanding. If Include locations are enabled, used, and order of precedence is understood in your environment, the entry may be created in a file in Include location.