Manual: pam_faillock

PAM_FAILLOCK(8)					      Linux-PAM Manual					     PAM_FAILLOCK(8)

NAME
       pam_faillock - Module counting authentication failures during a specified interval

SYNOPSIS

       auth ... pam_faillock.so {preauth|authfail|authsucc} [conf=/path/to/config-file] [dir=/path/to/tally-directory]
				[even_deny_root] [deny=n] [fail_interval=n] [unlock_time=n] [root_unlock_time=n]
				[admin_group=name] [audit] [silent] [no_log_info]

       account ... pam_faillock.so [dir=/path/to/tally-directory] [no_log_info]

DESCRIPTION
       This module maintains a list of failed authentication attempts per user during a specified interval and locks the
       account in case there were more than deny consecutive failed authentications.

       Normally, failed attempts to authenticate root will not cause the root account to become blocked, to prevent
       denial-of-service: if your users aren't given shell accounts and root may only login via su or at the machine console
       (not telnet/rsh, etc), this is safe.

OPTIONS
       {preauth|authfail|authsucc}
	   This argument must be set accordingly to the position of this module instance in the PAM stack.

	   The preauth argument must be used when the module is called before the modules which ask for the user credentials
	   such as the password. The module just examines whether the user should be blocked from accessing the service in
	   case there were anomalous number of failed consecutive authentication attempts recently. This call is optional if
	   authsucc is used.

	   The authfail argument must be used when the module is called after the modules which determine the authentication
	   outcome, failed. Unless the user is already blocked due to previous authentication failures, the module will
	   record the failure into the appropriate user tally file.

	   The authsucc argument must be used when the module is called after the modules which determine the authentication
	   outcome, succeeded. Unless the user is already blocked due to previous authentication failures, the module will
	   then clear the record of the failures in the respective user tally file. Otherwise it will return authentication
	   error. If this call is not done, the pam_faillock will not distinguish between consecutive and non-consecutive
	   failed authentication attempts. The preauth call must be used in such case. Due to complications in the way the
	   PAM stack can be configured it is also possible to call pam_faillock as an account module. In such configuration
	   the module must be also called in the preauth stage.

       conf=/path/to/config-file
	   Use another configuration file instead of the default /etc/security/faillock.conf.

       The options for configuring the module behavior are described in the faillock.conf(5) manual page. The options
       specified on the module command line override the values from the configuration file.

MODULE TYPES PROVIDED
       The auth and account module types are provided.

RETURN VALUES
       PAM_AUTH_ERR
	   An invalid option was given, the module was not able to retrieve the user name, no valid counter file was found,
	   or too many failed logins.

       PAM_BUF_ERR
	   Memory buffer error.

       PAM_CONV_ERR
	   The conversation method supplied by the application failed to obtain the username.

       PAM_INCOMPLETE
	   The conversation method supplied by the application returned PAM_CONV_AGAIN.

       PAM_SUCCESS
	   Everything was successful.

       PAM_IGNORE
	   User not present in passwd database.

NOTES
       Configuring options on the module command line is not recommend. The /etc/security/faillock.conf should be used
       instead.

       The setup of pam_faillock in the PAM stack is different from the pam_tally2 module setup.

       Individual files with the failure records are created as owned by the user. This allows pam_faillock.so module to
       work correctly when it is called from a screensaver.

       Note that using the module in preauth without the silent option specified in /etc/security/faillock.conf or with
       requisite control field leaks an information about existence or non-existence of a user account in the system because
       the failures are not recorded for the unknown users. The message about the user account being locked is never
       displayed for non-existing user accounts allowing the adversary to infer that a particular account is not existing on
       a system.

EXAMPLES
       Here are two possible configuration examples for /etc/pam.d/login. They make pam_faillock to lock the account after 4
       consecutive failed logins during the default interval of 15 minutes. Root account will be locked as well. The
       accounts will be automatically unlocked after 20 minutes.

       In the first example the module is called only in the auth phase and the module does not print any information about
       the account being blocked by pam_faillock. The preauth call can be added to tell users that their logins are blocked
       by the module and also to abort the authentication without even asking for password in such case.

       /etc/security/faillock.conf file example:

	   deny=4
	   unlock_time=1200
	   silent

       /etc/pam.d/config file example:

	   auth	    required	   pam_securetty.so
	   auth	    required	   pam_env.so
	   auth	    required	   pam_nologin.so
	   # optionally call: auth requisite pam_faillock.so preauth
	   # to display the message about account being locked
	   auth	    [success=1 default=bad] pam_unix.so
	   auth	    [default=die]  pam_faillock.so authfail
	   auth	    sufficient	   pam_faillock.so authsucc
	   auth	    required	   pam_deny.so
	   account  required	   pam_unix.so
	   password required	   pam_unix.so shadow
	   session  required	   pam_selinux.so close
	   session  required	   pam_loginuid.so
	   session  required	   pam_unix.so
	   session  required	   pam_selinux.so open

       In the second example the module is called both in the auth and account phases and the module informs the
       authenticating user when the account is locked if silent option is not specified in the faillock.conf.

	   auth	    required	   pam_securetty.so
	   auth	    required	   pam_env.so
	   auth	    required	   pam_nologin.so
	   auth	    required	   pam_faillock.so preauth
	   # optionally use requisite above if you do not want to prompt for the password
	   # on locked accounts
	   auth	    sufficient	   pam_unix.so
	   auth	    [default=die]  pam_faillock.so authfail
	   auth	    required	   pam_deny.so
	   account  required	   pam_faillock.so
	   # if you drop the above call to pam_faillock.so the lock will be done also
	   # on non-consecutive authentication failures
	   account  required	   pam_unix.so
	   password required	   pam_unix.so shadow
	   session  required	   pam_selinux.so close
	   session  required	   pam_loginuid.so
	   session  required	   pam_unix.so
	   session  required	   pam_selinux.so open

FILES
       /var/run/faillock/*
	   the files logging the authentication failures for users

	   Note: These files will disappear after reboot on systems configured with directory /var/run/faillock mounted on
	   virtual memory. For persistent storage use the option dir= in file /etc/security/faillock.conf.

       /etc/security/faillock.conf
	   the config file for pam_faillock options

SEE ALSO
       faillock(8), faillock.conf(5), pam.conf(5), pam.d(5), pam(8)

AUTHOR
       pam_faillock was written by Tomas Mraz.

[FIXME: source]						 07/16/2026					     PAM_FAILLOCK(8)