pam_succeed_if.so [flag...] [condition...]
pam_succeed_if.so is designed to succeed or fail authentication based on characteristics of the account belonging to the user being authenticated or values of other PAM items. One use is to select whether to load other modules based on this test.
The module should be given one or more conditions as module arguments, and authentication will succeed only if all of the conditions are met.
The following flags are supported:
Turns on debugging messages sent to syslog.
Evaluate conditions using the account of the user whose UID the application is running under instead of the user being authenticated.
Don't log failure or success to the system log.
Don't log failure to the system log.
Don't log success to the system log.
Log unknown users to the system log.
Conditions are three words: a field, a test, and a value to test for.
Available fields are user, uid, gid, shell, home, ruser, rhost, tty and service:
Field has a value numerically less than number.
Field has a value numerically less than or equal to number.
Field has a value numerically equal to number.
Field has a value numerically greater than or equal to number.
Field has a value numerically greater than number.
Field has a value numerically different from number.
Field exactly matches the given string.
Field does not match the given string.
Field matches the given glob.
Field does not match the given glob.
Field is contained in the list of items separated by colons.
Field is not contained in the list of items separated by colons.
User is in given group(s).
User is not in given group(s).
(user,host) is in given netgroup.
(user,host) is not in given netgroup.
The condition was true.
The condition was false.
A service error occurred or the arguments can't be parsed correctly.
To emulate the behaviour of pam_wheel, except there is no fallback to group 0 being only approximated by checking also the root group membership:
auth required pam_succeed_if.so quiet user ingroup wheel:root
Given that the type matches, only loads the othermodule rule if the UID is over 500. Adjust the number after default to skip several rules.
type [default=1 success=ignore] pam_succeed_if.so quiet uid > 500
type required othermodule.so arguments...