Implementation of pam_tally2.so counts successful logins as failures
This document (7011883) is provided subject to the disclaimer at the end of this document.
SUSE Linux Enterprise Server 12
SUSE Linux Enterprise Server 11
auth required pam_env.so auth required pam_unix.so auth required pam_tally2.so onerr=fail deny=6
After each successful login, the failed login count is incremented. After the number of successful logins matches the maximum failed login count the account is locked and the account has to be manually reset.
The user logs in successfully.
user1@server:~> ssh geeko@sles15sp3 Password: Last login: Fri Jul 16 10:56:54 2021 from 192.168.0.170 geeko@sles15sp3:~>
However, on the server pam_tally2 shows a login failure.
sles15sp3:~ # pam_tally2 Login Failures Latest failure From geeko 1 07/16/21 10:57:16 192.168.0.170
When the user correctly logs in after the sixth attempt (matching deny=6 above), they get an error and locked account.
user1@server:~> ssh geeko@sles15sp3 Password: Account locked due to 7 failed logins
The pam_tally2 command shows too many failed login attempts.
sles15sp3:~ # pam_tally2 Login Failures Latest failure From geeko 7 07/16/21 10:59:50 192.168.0.170
account required pam_tally2.so
In addition, if entries that contain pam_tally2.so have been added to other configuration files, they may need to be reordered so that the lines containing pam_tally2.so are the first entry in those configuration files.
The reason for this is because pam_tally2.so is not supported by pam-config. During an upgrade, or some updates, pam-config is used to verify and correct entries in the common-* files. This will cause any custom changes to be lost.
The pam-config method is the default configuration for SLES. Manual configuration requires disabling pam-config as indicated in the documentation here: 3.6 Manually configuring PAM
NOTE: With pam_tally2.so, incomplete authentications also count as a failure. During an authentication, the user name is entered and the failed login count is immediately increased by 1. The password is then entered correctly, the failed count is reset to zero. This means that if any authentication is 'abandoned', the failed login count will remain incremented by 1, until the next authentication occurs.
NOTE: In at least one case, the 'failed login count' problem was not seen when logging in via the console, but was seen when using ssh authentication. This may be the situation in all cases.
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- Document ID:7011883
- Creation Date: 05-Mar-2013
- Modified Date:30-Aug-2022
- SUSE Linux Enterprise Server
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