pam_authenticate() serves as an interface to the authentication mechanisms of the loaded modules.
flags is an optional parameter that may be specified by the following value:
Instruct the authentication modules to return
if the user does not have a registered authorization token.
Additionally, the value of flags may be
logically or'd with
The process may need to be privileged in order to successfully call this function.
User was not authenticated or process did not have sufficient privileges to perform authentication.
Application does not have sufficient credentials to authenticate the user.
Modules were not able to access the authentication information. This might be due to a network or hardware failure, etc.
Supplied username is not known to the authentication service.
One or more authentication modules has reached its limit of tries authenticating the user. Do not try again.
One or more authentication modules failed to load.
Note: Errors may be translated to text with pam_strerror().