How can I display a banner when someone attempts to ssh to my server?

This can be set with the Banner directive in sshd_config.

First create a banner to display upon connection:

root@root [~]# vi /etc/sshd_banner.txt
Set the Banner directive to point to this file and restart sshd:
root@root [~]# cd /etc/ssh/
root@root [/etc/ssh]# cp sshd_config sshd_config.save
root@root [/etc/ssh]# vi sshd_config
root@root [/etc/ssh]# diff sshd_config sshd_config.save
93c93
< Banner /etc/sshd_banner.txt
—
> #Banner /some/path
root@root [/etc/ssh]# /etc/init.d/sshd restart
Stopping sshd: [ OK ]
Starting sshd: [ OK ]
Test your new configuration:
root@root [/etc/ssh]# ssh 127.0.0.1

This is a test banner.
Your message/warning etc here.

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