6.33. pam_tally2 - login counter (tallying) module
pam_tally2.so [
file=/path/to/counter
] [
onerr=[fail|succeed]
] [
magic_root
] [
even_deny_root
] [
deny=n
] [
lock_time=n
] [
unlock_time=n
] [
root_unlock_time=n
] [
serialize
] [
audit
] [
silent
] [
no_log_info
]
pam_tally2 [
--file /path/to/counter
] [
--user username
] [
--reset[=n]
] [
--quiet
]
This module maintains a count of attempted accesses, can
reset count on success, can deny access if too many attempts fail.
pam_tally2 comes in two parts:
pam_tally2.so and
pam_tally2. The former is the PAM module and
the latter, a stand-alone program. pam_tally2
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.
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.
-
GLOBAL OPTIONS
This can be used for auth and
account module types.
-
onerr=[fail|succeed]
If something weird happens (like unable to open the file),
return with PAM_SUCCESS 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/tallylog.
-
audit
Will log the user name into the system log if the user is not found.
-
silent
Don't print informative messages.
-
no_log_info
Don't log informative messages via syslog(3).
-
AUTH OPTIONS
Authentication phase first increments attempted login counter and
checks if user should be denied access. If the user is authenticated
and the login process continues 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 sysadmin should use this
for user launched services, like su,
otherwise this argument should be omitted.
-
even_deny_root
Root account can become unavailable.
-
root_unlock_time=n
This option implies even_deny_root option.
Allow access after n seconds
to root account after failed attempt. If this option is used
the root user will be locked out for the specified amount of
time after he exceeded his maximum allowed attempts.
-
serialize
Serialize access to the tally file using locks. This option might
be used only for non-multithreaded services because it depends on
the fcntl locking of the tally file. Also it is a good idea to use
this option only in such configurations where the time between auth
phase and account or setcred phase is not dependent on the
authenticating client. Otherwise the authenticating client will be
able to prevent simultaneous authentications by the same user by
simply artificially prolonging the time the file record lock is held.
-
ACCOUNT OPTIONS
Account phase resets attempts counter if the user is
not magic root.
This phase can be used optionally 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 changed. The sysadmin should use this
for user launched services, like su,
otherwise this argument should be omitted.
6.33.3. MODULE TYPES PROVIDED
The auth and account
module types are provided.
- 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_USER_UNKNOWN
User not known.
pam_tally2 is not compatible with the old pam_tally faillog file format.
This is caused by requirement of compatibility of the tallylog file
format between 32bit and 64bit architectures on multiarch systems.
There is no setuid wrapper for access to the data file such as when the
pam_tally2.so module is called from
xscreensaver. As this would make it impossible to share PAM configuration
with such services the following workaround is used: If the data file
cannot be opened because of insufficient permissions
(EACCES) the module returns
PAM_IGNORE.
Add the following line to /etc/pam.d/login to
lock the account after 4 failed logins. Root account will be locked
as well. The accounts will be automatically unlocked after 20 minutes.
The module does not have to be called in the account phase because the
login calls pam_setcred(3) correctly.
auth required pam_securetty.so
auth required pam_tally2.so deny=4 even_deny_root unlock_time=1200
auth required pam_env.so
auth required pam_unix.so
auth required pam_nologin.so
account required pam_unix.so
password required pam_unix.so
session required pam_limits.so
session required pam_unix.so
session required pam_lastlog.so nowtmp
session optional pam_mail.so standard
/var/log/tallylogfailure count logging file
pam_tally2 was written by Tim Baverstock and Tomas Mraz.