PAM_SERVICE The service name (which identifies that PAM stack that the PAM functions will use to authenticate the program). PAM_USER The username of the entity under whose identity service will be given. That is, following authentication, PAM_USER identifies the local entity that gets to use the service. Note, this value can be mapped from something (eg., "anonymous") to something else (eg. "guest119") by any module in the PAM stack. As such an application should consult the value of PAM_USER after each call to a PAM function. PAM_USER_PROMPT The string used when prompting for a user's name. The default value for this string is a localized version of "login: ". PAM_TTY The terminal name: prefixed by /dev/ if it is a device file; for graphical, X-based, applications the value for this item should be the $DISPLAY variable. PAM_RUSER The requesting user name: local name for a locally requesting user or a remote user name for a remote requesting user. Generally an application or module will attempt to supply the value that is most strongly authenticated (a local account before a remote one. The level of trust in this value is embodied in the actual authentication stack associated with the application, so it is ultimately at the discretion of the system administrator. PAM_RUSER@PAM_RHOST should always identify the requesting user. In some cases, PAM_RUSER may be NULL. In such situations, it is unclear who the requesting entity is. PAM_RHOST The requesting hostname (the hostname of the machine from which the PAM_RUSER entity is requesting service). That is PAM_RUSER@PAM_RHOST does identify the requesting user. In some applications, PAM_RHOST may be NULL. In such situations, it is unclear where the authentication request is originating from. PAM_AUTHTOK The authentication token (often a password). This token should be ignored by all module functions besides pam_sm_authenticate3 and pam_sm_chauthtok3 . In the former function it is used to pass the most recent authentication token from one stacked module to another. In the latter function the token is used for another purpose. It contains the currently active authentication token. PAM_OLDAUTHTOK The old authentication token. This token should be ignored by all module functions except pam_sm_chauthtok3 . PAM_CONV The pam_conv structure. See pam_conv3 . PAM_FAIL_DELAY A function pointer to redirect centrally managed failure delays. See pam_fail_delay3 .