I can currently login to my server via ssh as root. There may be some other users, however, that have ssh access. I want to block out any possible logins except from root. How can I do this?
Server Fault is a question and answer site for system and network administrators. It only takes a minute to sign up.Sign up to join this community
So you can achieve your stated desire with the AllowUsers directive in your sshd_config file, for example:
$ grep AllowUsers /etc/ssh/sshd_config AllowUsers root
However I would be wary of using the root account for ssh - consider instead an unprivileged account for normal use, using something like sudo to acquire root privileges only when needed.
From man sshd_config
AllowUsers This keyword can be followed by a list of user name patterns, separated by spaces. If specified, login is allowed only for user names that match one of the patterns. Only user names are valid; a numerical user ID is not recognized. By default, login is allowed for all users. If the pat‐ tern takes the form USER@HOST then USER and HOST are separately checked, restricting logins to particular users from particular hosts. The allow/deny directives are processed in the following order: DenyUsers, AllowUsers, DenyGroups, and finally AllowGroups. See PATTERNS in ssh_config(5) for more information on patterns.
Btw. please don't allow passwords login for your root user. Only allow ssh keys or even better just allow a specific user to login and change to root but not root directly.