pam_tally2 command is used to lock and unlock ssh failed logins in linux like operating system. To implment a security feature like a user’s account must be locked after a number of failed login attempts . We can achieve this security via pam module called pam_tally2. This module can display user’s login attempts,set counts on individual basis, unlock all user counts.
pam_tally2 comes in two parts: pam_tally2.so and pam_tally2. The former is the PAM module and the latter, a stand-alone program. pam_tally2 is an application which can be used to interrogate and manipulate the counter file
In this article we will discuss how to lock and unlock user’s account after reaching a fixed number of failed ssh attempts in RHEL 6.X / CentOS 6.X
By default pam_tally2 module is already installed in linux. To set the lock and unlock rules, edit the two files : ‘/etc/pam.d/system-auth‘ & ‘/etc/pam.d/password-auth‘ and add the below line at the starting of auth section in both the files
auth required pam_tally2.so file=/var/log/tallylog deny=3 even_deny_root unlock_time=120
And then add the below line in the account Section in both the files
account required pam_tally2.so
Sample File of /etc/pam.d/system-auth
Sample File of /etc/pam.d/password-auth
- file=/var/log/tallylog – Default log file whic keep login counts.
- deny=3 – Deny access after 3 attempts and lock down user.
- even_deny_root – Policy is also apply to root user.
- unlock_time=1200 – Account will be locked till 20 Min after that it will be unlocked
Now Try to Login linux box with incorrect password :
Now check user’s login attempts using pam_tally2 Command
[root@localhost ~]# pam_tally2 -u nextstep4it Login Failures Latest failure From nextstep4it 3 06/14/14 02:01:25 192.168.1.8
Now reset or unlock user’s account’s using pam_tally2 command :
[root@localhost ~]# pam_tally2 --user nextstep4it --reset Login Failures Latest failure From nextstep4it 4 06/14/14 02:20:42 192.168.1.8
Now Verify the login Attempt is reset or not
[root@localhost ~]# pam_tally2 --user nextstep4it Login Failures Latest failure From nextstep4it 0