SSH is a great way to remotely administer a server. However, it still has a number of issues when you open it up to the world. The server and client communications are secure but that doesn
First things first, sshd_config. In Ubuntu this is usually found in /etc/ssh and can be used to configure a great number of features. The simplest ones to deal with are always the best. Restricting the users who can login via SSH is a first principle. This can be done in one of two ways, by user or by group. AllowGroups allows any user in this group authenticated access to the server via SSH. A more fine grained approach is to use the AllowUsers option.

The link for this article located at ubuntugeek is no longer available.