How to DENY SSH access for certain user on Linux

Due to some security reason, you may require to block certain user SSH access to Linux box.

Edit the sshd_config file, the location will sometimes be different depend on Linux distribution, but it’s usually in /etc/ssh/.

Open the file up while logged on as root:

vi /etc/ssh/sshd_config

Insert a line:

DenyUsers username1 username2 username3 username4

Referring to #man sshd_config:

    DenyUsers
    separated by spaces. Login is disallowed for user names that
    match one of the patterns. â*â and â?â can be used as wildcards
    in the patterns. Only user names are valid; a numerical user ID
    is not recognized. By default, login is allowed for all users.
    If the pattern takes the form USER@HOST then USER and HOST are
    separately checked, restricting logins to particular users from
    particular hosts.

Save it and restart SSH services. Basically username1, username2, username3 & username4 SSH login is disallowed.

/etc/init.d/sshd restart

Reference: http://www.planetmy.com/blog/