Here is a detailed article on restricting SSH access for users in the wheel group using PAM on Red Hat 9.
Introduction
In a Linux system, the wheel group is a special group that includes users who have root-like privileges. However, it is essential to restrict the SSH access of these users to maintain system security. This article will guide you on how to restrict SSH access for users in the wheel group using PAM (Pluggable Authentication Modules) on Red Hat 9.
Prerequisites
Before proceeding, ensure that you have root access to the system and are familiar with editing configuration files using a text editor like vi or nano.
Steps to Restrict SSH Access
Step 1: Create a Custom PAM Configuration File
Create a new file named wheel_sshd in the /etc/pam.d/ directory:
sudo touch /etc/pam.d/wheel_sshd
Step 2: Edit the Custom PAM Configuration File
Open the wheel_sshd file using your preferred text editor:
sudo vi /etc/pam.d/wheel_sshd
Add the following lines to the file:
auth required pam_wheel.so use_uid
account required pam_wheel.so use_uid
password required pam_wheel.so use_uid
Save and close the file.
Step 3: Modify the SSHD Configuration File
Open the sshd_config file using your preferred text editor:
sudo vi /etc/ssh/sshd_config
Find the line that starts with AllowGroups and add the wheel group to it:
AllowGroups wheel
Save and close the file.
Step 4: Restart the SSHD Service
Restart the SSHD service to apply the changes:
sudo service sshd restart
Summary
In this article, we learned how to restrict SSH access for users in the wheel group using PAM on Red Hat 9. We created a custom PAM configuration file, edited it to include the necessary lines, modified the SSHD configuration file, and restarted the SSHD service.