How does pam authentication work

The PAM library provides the framework to load the appropriate modules and to manage the stacking process. The PAM library provides a generic structure to which all of the modules can plug in. See the pam. The stacking feature can require that a user remembers several passwords. With the password-mapping feature, the primary password is used to decrypt the other passwords. The user does not need to remember or enter multiple passwords.

The other option is to synchronize the passwords across each authentication mechanism. This strategy could increase the security risk, because the mechanism security is limited by the least secure password method that is used in the stack.

The Solaris 9 release includes several enhancements to the PAM service. The following list highlights the most important changes:. The capabilities are provided by the following modules:. See PAM Modules for information about the new modules. The ssh service name was added. The PAM configuration file was updated. See Generic pam. Update 2 includes a new binding control flag. This flag provides the ability to skip additional authentication if the service module returns success and if no preceding required modules have failed.

The control flag is documented in the pam. This section discusses some tasks that might be required to make the PAM framework fully functional. In particular, you should be aware of some security issues that are associated with the PAM configuration file. When you are deciding how best to use PAM in your environment, start by focusing on these issues:.

Make sure to consider the security implications of the sufficient and optional control flags. Review the man pages that are associated with the modules. These man pages can help you understand how each module functions, what options are available, and the interactions between stacked modules. If the PAM configuration file is misconfigured or the file becomes corrupted, even superuser might be unable to log in. Since the sulogin command does not use PAM, superuser would then be required to boot the machine into single-user mode and fix the problem.

Test all the commands that might have been affected by your changes. An example is adding a new module to the telnet service. In this example, you use the telnet command and verify that your changes make the service behave as expected. Set the permissions so that the module file is owned by root and that permissions are You must test before the system is rebooted in case the configuration file is misconfigured.

Run rlogin , su , and telnet before you reboot the system. The service might be a daemon that is spawned only once when the system is booted. Then you must reboot the system before you can verify that the module has been added. Therefore, this step prevents unauthenticated access to the local system from remote systems.

Changing the PAM configuration file does not prevent the service from being started. In the following example, all alert messages are displayed on the console.

Critical messages are mailed to root. Each line in the log contains a time stamp, the name of the system that generated the message, and the message. The pamlog file is capable of logging a large amount of information. PAM uses run-time pluggable modules to provide authentication for system entry services. A stacking feature is provided to let you authenticate users through multiple services.

Also provided is a password-mapping feature to not require that users remember multiple passwords. Every PAM module implements a specific mechanism. When you set up PAM authentication, you need to specify both the module and the module type, which defines what the module does. More than one module type, such as auth, account, session, or password, can be associated with each module. The following table describes every PAM module, and includes the module name and the module file name.

The path of each module is determined by the instruction set that is available in the Solaris release that is installed. See the isalist 5 man page for more information. Provides support for password management. This module performs various checks on passwords. Those check are for the length of the password, for circular shift of the login name, for password complexity, and for the amount of variation between new passwords and old passwords. Provides password prompting for authentication and password management.

Provides support for authentication only. This module updates the authentication token for the user. Linux Pluggable Authentication Modules PAM is a suite of libraries that allows a Linux system administrator to configure methods to authenticate users. How does PAM work?

PAM solutions take privileged account credentials — i. Once inside the vault, system administrators need to go through the PAM system to access the credentials, at which point they are authenticated and their access is logged. A pluggable authentication module PAM is a mechanism to integrate multiple low-level authentication schemes into a high-level application programming interface API.

PAM allows programs that rely on authentication to be written independently of the underlying authentication scheme. Linux-PAM is a system of libraries that handle the authentication tasks of applications services on the system.

The library provides a stable general interface Application Programming Interface — API that privilege granting programs such as login 1 and su 1 defer to to perform standard authentication tasks. Privileged access management helps organizations make sure that that people have only the necessary levels of access to do their jobs.

PAM allows for a much more robust authentication environment than per-application services could provide. It has been in Linux for many, many years, and is involved with nearly all user identification processes. More about me. Relive our April event with demos, keynotes, and technical sessions from experts, all available on demand.

Enable Sysadmin. Learn how Pluggable Authentication Modules are used to help applications make proper use of user accounts in Linux. Topics: Linux. On Demand: Red Hat Summit Virtual Experience Relive our April event with demos, keynotes, and technical sessions from experts, all available on demand. Watch Now. Related Content Image. Build a lab in 36 seconds, run Podman on a Mac, and more tips for sysadmins. Check out Enable Sysadmin's top 10 articles from October Posted: November 2, Author: Vicki Walker Red Hat.

How to package open source applications as RPMs. Want to use a piece of third-party software but there's no RPM to install it? No problem: You can customize third-party software packages with RPM.