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Cumulus Linux

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Single User Mode - Password Recovery

In Cumulus Linux 5.6, you can’t reset the root password by booting into Cumulus Linux single-user recovery mode. To work around this issue, reset the cumulus or root user password as follows:

  1. Use df / to determine which device is mounted on /. If you cannot access the switch but another switch with the same hardware is available, use df / on that switch to find the device.

  2. Reboot the switch.

  3. In the GRUB menu, select ONIE, then in the GRUB ONIE menu, select ONIE Rescue.

  4. When prompted, press enter.

  5. Mount the device in step 1 with the mount $DEVICE /mnt command.

    If you did not determine the mount point in step 1, you can use the df command to determine which devices to try; for example, if /mnt/onie-boot is on /dev/sda2, try mount /dev/sda4 /mnt. If this is the correct device, ls /mnt shows a root file system and ls /mnt/etc/shadow shows a file.

  6. Run chroot /mnt, then run passwd cumulus or passwd root.

  7. Exit, then reboot.

Use single user mode to assist in troubleshooting system boot issues or for password recovery.

To enter single user mode:

  1. Boot the switch, then as soon as you see the GRUB menu, use the arrow keys to select Advanced options for Cumulus Linux GNU/Linux.

    Before the GRUB menu appears, the switch goes through the boot cycle. Do not interrupt this autoboot process when you see the following lines; wait until you see the GRUB menu.

    ...
USB0:  Bringing USB2 host out of reset...
Net:   eth-0
SF:    MX25L6405D with page size 4 KiB, total 8 MiB
Hit any key to stop autoboot:  2


                 GNU GRUB  version 2.02+dfsg1-20

+----------------------------------------------------------------------------+
|*Cumulus Linux GNU/Linux                                                    |
| Advanced options for Cumulus Linux GNU/Linux                               |
| ONIE                                                                       |
|                                                                            |
+----------------------------------------------------------------------------+

  2. Select Cumulus Linux GNU/Linux, with Linux 4.19.0-cl-1-amd64 (recovery mode).

                 GNU GRUB  version 2.02+dfsg1-20

+----------------------------------------------------------------------------+
| Cumulus Linux GNU/Linux, with Linux 4.19.0-cl-1-amd64                       |
|*Cumulus Linux GNU/Linux, with Linux 4.19.0-cl-1-amd64 (recovery mode)       |
|                                                                            |
+----------------------------------------------------------------------------+

  3. After the system reboots, set a new root password. The root user provides complete control over the switch.

    root@switch:~# passwd
Enter new UNIX password:
Retype new UNIX password:
passwd: password updated successfully

    You can take this opportunity to reset the password for the cumulus account.

       root@switch:~# passwd cumulus
   Enter new UNIX password:
   Retype new UNIX password:
   passwd: password updated successfully

  4. Sync the /etc directory, then reboot the system:

    root@switch:~# sync
root@switch:~# reboot -f
Restarting the system.

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