From Newsgroup: alt.os.linux.ubuntu
CtrlAltDel wrote:
On Sun, 10 May 2026 11:51:04 +0100, PC-3FingerSalute wrote:
If CtrlAltDel is trying to make a joke of sorts, then it is a very lame
joke.
If CtrlAltDel really cannot see the difference between "PAM" and "RAM"
at 32px, the headline font size on that web page, then a visit to the
optician is needed.
What's the difference between PAM and RAM, Mr. Genius?
Google AI says..
PAM stands for Pluggable Authentication Modules.
In simple terms, it is a flexible framework that Linux uses to handle
how you log in and prove who you are to the system. Instead of every
single app (like SSH, your desktop login, or sudo) having its own code
to check passwords, they all talk to PAM.
Think of PAM like a universal wall socket: different "plugs" (modules)
can be swapped in or out without changing the appliance (the
application) itself.
Why does it matter?
-a-a-a rCo Decoupling: Developers don't have to write custom code for every authentication method (fingerprints, passwords, LDAP, etc.). They just
ask PAM, "Is this person who they say they are?"
-a-a-a rCo Flexibility: As an admin, you can change your system from using standard passwords to using YubiKeys or Google Authenticator just by
editing a text file, without ever touching the source code of your apps.
How it works
PAM organizes its work into four main "management groups," often seen in configuration files:
-a-a-a rCo auth (Authentication): Verifies the user's identity (e.g., "Enter your password").
-a-a-a rCo account (Account Management): Checks if the account is actually allowed to log in right now (e.g., has the password expired? Is it after
work hours?).
-a-a-a rCo password (Password Management): Handles the process of updating the authentication token (e.g., when you run the passwd command).
-a-a-a rCo session (Session Management): Handles tasks that happen at the start and end of a session (e.g., mounting a home directory or logging
the login time).
Key Files and Directories
If you want to see PAM in action on your own system, look at these
locations:
-a-a-a rCo /etc/pam.d/: This directory contains the configuration files for every PAM-aware application (e.g., sshd, sudo, login).
-a-a-a rCo /usr/lib/security/: This is usually where the actual module files (ending in .so) are stored. These are the "plugins" that do the heavy
lifting.
A Practical Example
If you look at the Arch Linux Wiki on PAM, you'll see that when you run
sudo, it checks its configuration in /etc/pam.d/sudo. That file might
tell PAM to first check your password using pam_unix.so and then check
if you're in the right group using pam_wheel.so.
Warning: Be very careful when editing these files! One typo can lock
everyone (including the root user) out of the system entirely. It is
always a good idea to keep a root terminal open while testing changes so
you can undo them if things break.
--
Linux Mint 22.3
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