Description: PAM (Pluggable Authentication Modules) are a flexible and modular authentication architecture used in Unix-like operating systems, including Linux distributions. Their main function is to allow the implementation of authentication policies in a simple and efficient manner, facilitating the integration of different authentication methods into a single system. PAM allows system administrators to define how users are authenticated and which methods are used, such as passwords, token-based authentication, biometrics, among others. This modularity means that modules can be added, removed, or modified without the need to rewrite the code of the applications that depend on them. PAM modules are loaded dynamically, providing great flexibility and adaptability to the security needs of each system. Additionally, their design allows multiple authentication methods to be used together, enhancing the overall security of the system. PAM is an integral part of user management and system security in many operating systems, and its configuration is done through configuration files that specify the behavior of each module in different contexts, such as login, password management, and access to specific services.
History: PAM modules were introduced in 1995 by the Linux project as a solution to the growing need for a flexible and secure authentication system. Their development was driven by the need to simplify authentication management in Unix and Linux systems, allowing administrators to implement different authentication methods without modifying existing applications. Since their inception, PAM has evolved and become a standard in most Unix-like operating systems, where it has been deeply integrated into user management systems.
Uses: PAM modules are primarily used to manage user authentication in Unix-like systems. They allow administrators to define authentication policies that can include multiple methods, such as passwords, two-factor authentication, and biometrics. Additionally, PAM is used to control access to specific services, such as SSH, sudo, and others, ensuring that only authorized users can access critical system resources.
Examples: A practical example of using PAM is the configuration of two-factor authentication for SSH access, where a PAM module for password authentication can be combined with another module that requires a verification code sent to a mobile device. Another case is the implementation of account lockout policies after several failed login attempts, using the ‘pam_tally2’ module.
