PAM Lockout Module

I recently used the PAM Lockout Module as part of my software testing, and I have to say, I was impressed with its functionality. This PAM module serves the purpose of locking out users or groups from accessing the machine. The module exclusively focuses on authentication queries, and you can pass users and groups via command line arguments. One use case for this module can be limiting the root from gaining remote access.

When working with this module, I found that the arguments should always take the form of 'user=' or 'group=', and should NOT contain any spaces. To ensure that the locked-out users do not access other PAM modules, I placed the module at the head of the stack.

Furthermore, in order for group or user lockout to work, the module requires the use of the getpwnam(3) or getgrnam(3) functions. User comparisons are done by using the pw_uid field in the passwd structure. Therefore, any user with an ID of zero, as per the sample usage mentioned earlier, will be locked out. Similarly, group comparisons utilize string comparisons of the inbound user and the names returned by getgrnam(3).

Overall, the PAM Lockout Module is an effective tool for limiting access to your machine. It is easy to use and provides excellent control over who can access your system.