This module maintains a count of attempted accesses, can reset count on success, can deny access if too many attempts fail.
pam_tally comes in two parts:
pam_tally.so
and
pam_tally. The former is the PAM module and the latter, a stand-alone program.
pam_tally
is an (optional) application which can be used to interrogate and manipulate the counter file. It can display users' counts, set individual counts, or clear all counts. Setting artificially high counts may be useful for blocking users without changing their passwords. For example, one might find it useful to clear all counts every midnight from a cron job. The
faillog(8)
command can be used instead of pam_tally to to maintain the counter file.
Normally, failed attempts to access
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
GLOBAL OPTIONS
This can be used for
auth
and
account
services.
onerr=[fail|succeed]
If something weird happens (like unable to open the file), return with
PAM_SUCESS
if
onerr=succeed
is given, else with the corresponding PAM error code.
file=/path/to/counter
File where to keep counts. Default is
/var/log/faillog.
audit
Will display the username typed if the user is not found.
AUTH OPTIONS
Authentication phase first checks if user should be denied access and if not it increments attempted login counter. Then on call to
pam_setcred(3)
it resets the attempts counter.
deny=n
Deny access if tally for this user exceeds
n.
lock_time=n
Always deny for
n
seconds after failed attempt.
unlock_time=n
Allow access after
n
seconds after failed attempt. If this option is used the user will be locked out for the specified amount of time after he exceeded his maximum allowed attempts. Otherwise the account is locked until the lock is removed by a manual intervention of the system administrator.
magic_root
If the module is invoked by a user with uid=0 the counter is not incremented. The sys-admin should use this for user launched services, like
su, otherwise this argument should be omitted.
no_lock_time
Do not use the .fail_locktime field in
/var/log/faillog
for this user.
no_reset
Don't reset count on successful entry, only decrement.
even_deny_root_account
Root account can become unavailable.
even_deny_root_account
Root account can become unavailable.
per_user
If
/var/log/faillog
contains a non-zero .fail_max/.fail_locktime field for this user then use it instead of
deny=n/
lock_time=n
parameter.
no_lock_time
Don't use .fail_locktime filed in
/var/log/faillog
for this user.
ACCOUNT OPTIONS
Account phase resets attempts counter if the user is
not
magic root. This phase can be used optionaly for services which don't call
pam_setcred(3)
correctly or if the reset should be done regardless of the failure of the account phase of other modules.
magic_root
If the module is invoked by a user with uid=0 the counter is not incremented. The sys-admin should use this for user launched services, like
su, otherwise this argument should be omitted.
no_reset
Don't reset count on successful entry, only decrement.
MODULE SERVICES PROVIDED
The
auth
and
account
services are supported.
RETURN VALUES
PAM_AUTH_ERR
A invalid option was given, the module was not able to retrive the user name, no valid counter file was found, or too many failed logins.
PAM_SUCCESS
Everything was successfull.
PAM_USER_UNKNOWN
User not known.
EXAMPLES
Add the following line to
/etc/pam.d/login
to lock the account after too many failed logins. The number of allowed fails is specified by
/var/log/faillog
and needs to be set with pam_tally or
faillog(8)
before.