Understanding Linux Pluggable Authentication Modules (PAM)
Linux uses Pluggable Authentication Modules (PAM) to decouple system applications (such as sshd, login, sudo, and su) from underlying authentication mechanisms. Instead of hardcoding authentication logic into each daemon, applications dynamically link against PAM (libpam.so). To verify whether a service supports PAM, check its dynamic libraries with ldd: ldd $(which sshd) | grep pam # libpam.so.0 => /lib64/libpam.so.0 (0x00007f81348fc000) PAM Configuration Structure PAM configuration files reside in /etc/pam.d/. Each service typically has its own configuration file (e.g., /etc/pam.d/sshd, /etc/pam.d/sudo). ...