Oracle Linux, recognized for its stability and robustness, serves as a cornerstone for enterprise applications and databases, thanks in part to its Unbreakable Enterprise Kernel (UEK). However, even in the most secure and well-managed environments, situations arise where the root password needs to be reset. Whether due to forgotten passwords or inherited systems with unknown credentials, this guide will navigate Oracle Linux users through the process of resetting the root password, with a focus on handling the nuances associated with Oracle’s UEK.

Preparing for Password Reset

Before proceeding with the root password reset, ensure you have physical or console access to the server. If you’re using a virtual machine, access through the VM console will suffice. You’ll also need to reboot the system, so ensure that any critical applications are safely shut down or moved to a maintenance window to minimize impact.

Accessing GRUB Menu

1. Reboot Your Oracle Linux System: Initiate a system reboot. As the system starts, watch for prompts to enter the boot menu or GRUB menu. On Oracle Linux, this usually involves pressing a key like Esc or Shift during boot-up.
2. Edit GRUB Menu Entry: Once in the GRUB menu, highlight the Oracle Linux kernel you wish to boot (typically the first option if you haven’t customized your boot entries). Press e to edit the boot parameters.

Modifying Boot Parameters for UEK

1. Find the Kernel Boot Line: Look for the line starting with linux or linux16, which specifies the kernel boot parameters. This line will include various options and the path to the UEK.
2. Append Emergency Boot Parameters: To reset the root password, you’ll need to modify this line to instruct the system to boot into a single-user mode or emergency mode. Append rd.break to the end of the line for systems using the UEK. This command interrupts the boot process before pivoting to the real root filesystem, giving you a chance to reset the password.
3. Boot with Modified Parameters: Press Ctrl + X or F10 to boot with the modified parameters. The system will boot into an emergency shell session.

Resetting the Root Password

Once in the emergency shell, follow these steps to reset the root password:

1. Remount the Root Filesystem: Initially, the root filesystem is mounted as read-only. Remount it as read-write to make changes:

mount -o remount,rw /sysroot

2. Chroot into the System: Use the chroot command to change the root directory to the system’s root directory. This allows you to operate as if you were logged into the system normally:

chroot /sysroot

3. Change the Root Password: Use the passwd command to initiate the password change for the root account:

passwd

Follow the prompts to enter and confirm the new password. Choose a strong and secure password to enhance system security.

4. Ensure SELinux Contexts are Preserved: On Oracle Linux, SELinux is often enforced. Ensure that the SELinux file contexts are correctly labeled during the next boot:

touch /.autorelabel

5. Exit and Reboot: Type exit to leave the chroot environment, then issue another exit command to exit the emergency shell. Reboot your system:

reboot

Your Oracle Linux system will reboot, and you should be able to log in with the new root password.

Post-Reset Considerations

After resetting the root password, it’s crucial to review your system’s security policies. Ensure that only authorized personnel have root access and consider implementing additional security measures, such as two-factor authentication and regular password changes, to protect your system.

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