Owl: tcb: Components (cont.) pam_tcb, the PAM module Provides functionality for all four PAM management groups Supports /etc/passwd, /etc/shadow, /etc/tcb/ directory structure, NIS, and NIS+ for password changes Supports arbitrary password hashing methods Optional forking to keep address space clean Backwards compatible with Linux-PAM pam_unix and pam_pwdb but offers additional functionality and better code quality