PAM filter module
' pam_filter.so 'u pam_filter.so [debug] [new_term] [non_term] run1|run2 filter [ . . . ]
This module is intended to be a platform for providing access to all of the input/output that passes between the user and the application . It is only suitable for tty -based and (stdin/stdout) applications .
To function this module requires filters to be installed on the system . The single filter provided with the module simply transposes upper and lower case letters in the input and output streams . (This can be very annoying and is not kind to termcap based editors) .
Each component of the module has the potential to invoke the desired filter . The filter is always execv (2) with the privilege of the calling application and not that of the user . For this reason it cannot usually be killed by the user without closing their session .
debug Print debug information .
new_term The default action of the filter is to set the PAM_TTY item to indicate the terminal that the user is using to connect to the application . This argument indicates that the filter should set PAM_TTY to the filtered pseudo -terminal .
non_term don (Aqt try to set the PAM_TTY item .
runX In order that the module can invoke a filter it should know when to invoke it . This argument is required to tell the filter when to do this .
filter The full pathname of the filter to be run and any command line arguments that the filter might expect .
All module types ( auth , account , password and session )are provided .
PAM_SUCCESS The new filter was set successfully .
PAM_ABORT Critical error, immediate abort .
Add the following line to /etc/pam .d/login to see how to configure login to transpose upper and lower case letters once the user has logged in:.RS 4
session required pam_filter .so run1 /lib/security/pam_filter/upperLOWER
pam.conf(5), pam.d(5), pam(8)
pam_filter was written by Andrew G . Morgan <morgan@kernel .org> .