How to configure pam_tally2 to lock user account after certain number of failed login attempts ?
문제
- How to configure
pam_tally2
to lock user account after certain number of failed login attempts ?
환경
- Red Hat Enterprise Linux 6
- pam
해결
To configure pam_tally2 to lock a user account after certain number of failed login attempts, refer the steps below :
1. Add the following line in auth and account section of /etc/pam.d/system-auth
and/etc/pam.d/password-auth
files.
auth required pam_tally2.so deny=3 onerr=fail unlock_time=500
account required pam_tally2.so
2. The sample system-auth file will looks as follows :
#%PAM-1.0
# This file is auto-generated.
# User changes will be destroyed the next time authconfig is run.
auth required pam_env.so
auth required pam_tally2.so deny=3 onerr=fail unlock_time=300
auth sufficient pam_unix.so nullok try_first_pass
auth requisite pam_succeed_if.so uid >= 500 quiet
auth required pam_deny.so
account required pam_tally2.so
account required pam_unix.so broken_shadow
account sufficient pam_succeed_if.so uid < 500 quiet
account required pam_permit.so
password requisite pam_cracklib.so try_first_pass retry=3
password sufficient pam_unix.so sha512 shadow nullok try_first_pass use_authtok
password required pam_deny.so
session optional pam_keyinit.so revoke
session required pam_limits.so
session [success=1 default=ignore] pam_succeed_if.so service in crond quiet use_uid
session required pam_unix.so
The order of the pam rules are important. auth required pam_tally2.so
should be above ofauth sufficient pam_unix.so
.
On RHEL6, pam_tally2 entries needs to be present in both system-auth
and password-auth
files.
3. The pam_tally2 is not compatible with the old pam_tally faillog file format. By default the file that keeps the failed login counter is /var/log/tallylog.
Make sure tallylog permission is 600.
# chmod 600 /var/log/tallylog ; chown root:root /var/log/tallylog
else It will log error message like below in /var/log/secure
.
var/log/secure:Nov 20 18:43:17 localhost login: pam_tally2(login:auth): /var/log/tallylog is either world writable or not a normal file
var/log/secure:Nov 20 18:43:23 localhost login: pam_tally2(login:auth): /var/log/tallylog is either world writable or not a normal file
To check the list of users hitting maximum attempts command is "pam_tally2".
# pam_tally2
# pam_tally2 -u testuser
To reset the number of fail login counter by following command.
# pam_tally2 -r -u testuser
*If you want to lock root user, please add "even_deny_root" to the pam_tally2.so line in the auth section of the /etc/pam.d/system-auth file (and also the password-auth file if needed).
auth required pam_tally2.so deny=3 onerr=fail unlock_time=60 even_deny_root
account required pam_tally2.so
Note: no_magic_root
option is not required to be configured in pam_tally2
in RHEL 6 since normally, failed attempts to access root will not cause the root account to become blocked.
For more detail of pam_tally2:
/usr/share/doc/pam-{Version}/txts/README.pam_tally2
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