what you mean by PAM in linux

Hi..
PAM stands for Pluggable Authentication Modules. PAM is a library, used to control the function of various applications that have the capability to use the PAM libraries. PAM is based on a series of library modules, some of which depend on configuration files. Locations of PAM configuration files and library modules are:

* All PAM applications are configured in the directory "/etc/pam.d" or in a file "/etc/pam.conf".
* The library modules are normally stored in the directory "/lib/security".
* The configuration files are located in the directory "/etc/security".

To configure PAM, on systems already set up for it, you would need to edit the files for the service you want to modify in the "/etc/pam.d" directory, and modify the appropriate configuration file in the directory "/etc/security".