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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}
                                [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, succeded.
           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.
       dir=/path/to/tally-directory
           The directory where the user files with the failure records are
           kept. The default is /var/run/faillock.
       audit
           Will log the user name into the system log if the user is not
           found.
       silent
           Don't print informative messages. This option is implicite in the
           authfail and authsucc functions.
       no_log_info
           Don't log informative messages via syslog(3).
       deny=n
           Deny access if the number of consecutive authentication failures
           for this user during the recent interval exceeds n. The default is
           3.
       fail_interval=n
           The length of the interval during which the consecutive
           authentication failures must happen for the user account lock out
           is n seconds. The default is 900 (15 minutes).
       unlock_time=n
           The access will be reenabled after n seconds after the lock out.
           The default is 600 (10 minutes).
           If the n is set to never or 0 the access will not be reenabled at
           all until administrator explicitly reenables it with the faillock
           command. Note though that the default directory that pam_faillock
           uses is usually cleared on system boot so the access will be also
           reenabled after system reboot. If that is undesirable a different
           tally directory must be set with the dir option.
           Also note that it is usually undesirable to permanently lock out
           the users as they can become easily a target of denial of service
           attack unless the usernames are random and kept secret to potential
           attackers.
       even_deny_root
           Root account can become locked as well as regular accounts.
       root_unlock_time=n
           This option implies even_deny_root option. Allow access after n
           seconds to root account after the account is locked. In case the
           option is not specified the value is the same as of the unlock_time
           option.
       admin_group=name
           If a group name is specified with this option, members of the group
           will be handled by this module the same as the root account (the
           options even_deny_root> and root_unlock_time will apply to them. By
           default the option is not set.
MODULE TYPES PROVIDED
       The auth and account module types are provided.
RETURN VALUES
       PAM_AUTH_ERR
           A 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_SUCCESS
           Everything was successful.
       PAM_IGNORE
           User not present in passwd database.
NOTES
       pam_faillock setup in the PAM stack is different from the pam_tally2
       module setup.
       The 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 or with
       requisite control field leaks an information about existence or
       non-existence of an 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 nonexisting 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 blocking by
       pam_faillock. The preauth call can be added to tell the user that his
       login is blocked by the module and also to abort the authentication
       without even asking for password in such case.
           auth     required       pam_securetty.so
           auth     required       pam_env.so
           auth     required       pam_nologin.so
           # optionally call: auth requisite pam_faillock.so preauth deny=4 even_deny_root unlock_time=1200
           # to display the message about account being locked
           auth     [success=1 default=bad] pam_unix.so
           auth     [default=die]  pam_faillock.so authfail deny=4 even_deny_root unlock_time=1200
           auth     sufficient     pam_faillock.so authsucc deny=4 even_deny_root unlock_time=1200
           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 gives the authenticating user message when the
       account is locked
           auth     required       pam_securetty.so
           auth     required       pam_env.so
           auth     required       pam_nologin.so
           auth     required       pam_faillock.so preauth silent deny=4 even_deny_root unlock_time=1200
           # optionally use requisite above if you do not want to prompt for the password
           # on locked accounts, possibly with removing the silent option as well
           auth     sufficient     pam_unix.so
           auth     [default=die]  pam_faillock.so authfail deny=4 even_deny_root unlock_time=1200
           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
SEE ALSO
       faillock(8), pam.conf(5), pam.d(5), pam(8)
AUTHOR
       pam_faillock was written by Tomas Mraz.

Linux-PAM Manual                  04/01/2020                   PAM_FAILLOCK(8)