Limit_SSH_logins

Purpose

To prevent (read make more difficult) brute force attacks to your ssh server exposed on the internet, you can limit which logins can be used to log in with ssh protocol.

Steps

1. Edit file /etc/pam.d/sshd, add the following line as the first line: auth required pam_listfile.so sense=allow item=user file=/etc/ssh/ssh_allow_users onerr=fail

2. Create a new file /etc/ssh/ssl_allow_users, in which put the user id that is allowed for SSH login. -- You may actually put multiple user ids in this file, each in a separate line, for example:

jihe
lucy
other_user

3. Do /sbin/service sshd restart

Credits

This TIP is a copy of information from : http://www.jihe.net/technical/my_linux_whitebox/stop_ssh_brute_force_attack.php Thank you, Ji He.