Some organizations configure servers to print an obnoxious banner message that is displayed everytime someone logs in via SSH. This message will typically say something along the lines of unauthorized access is forbidden and that actions will be monitored, etc. This is likely as effective in preventing unauthorized access as the equally obnoxious e-mail footers that say that this email is only for the recipient and reading it is forbidden if you are not the intended recipient, etc are at preventing unauthorized reading of emails.

Fortuneately, it is rather easy to suppress these banners by adjusting the LogLevel in your SSH client.

In OpenSSH this is how to do it:

ssh -o LogLevel=error user@example.com

Using the ssh -q option will also work but this will suppress a lot of other messages as well.