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pam_tally2 — The login counter (tallying) module

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DESCRIPTION

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.

OPTIONS

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.

NOTES

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.

EXAMPLES

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

AUTHOR

pam_tally2 was written by Tim Baverstock and Tomas Mraz.