Introduction

By default, switching to the root user using su - requires the root password. In environments where trusted administrators require frequent root access, Linux allows you to configure passwordless root access either through the wheel group or by using sudo.

Prerequisites

Before you begin, ensure you have:

  • Root or administrative access to the server
  • A Linux system with PAM support
  • A user account to grant privileged access

Implementation

Method 1: Configure the Wheel Group

Step 1: Create a User

useradd test
passwd test

Step 2: Add the User to the Wheel Group

usermod -aG wheel test

Step 3: Update the PAM Configuration

Edit the PAM configuration file:

vi /etc/pam.d/su

Uncomment the following line:

auth sufficient pam_wheel.so trust use_uid

On some older Linux distributions, the entry may appear as:

auth sufficient /lib/security/$ISA/pam_wheel.so trust use_uid

Save the file and exit.

Step 4: Test the Configuration

Log in as the user and execute:

su -

The user should now switch to the root account without being prompted for the root password.

Method 2: Configure Passwordless sudo

Edit the sudoers file:

visudo

Add the following entry:

test ALL=(ALL) NOPASSWD:ALL

Save the file and exit.

The user can now become root using:

sudo su -

Conclusion

You can allow a trusted user to become the root user without entering a password using either the wheel group with PAM or sudo with the NOPASSWD option. While both methods achieve the same result, sudo is generally the preferred approach as it provides better control and auditing of privileged access.

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