Reset Password if forget username and password

Example: Reset Password

Reference model:

• Switch model name: AS7726-32X
• Edgecore SONiC version: SONiC.Edgecore-SONiC_20200827_110345_ec201911_2020-aug_enhanced_178

Procedure :

Step 1: Reboot system and press “e” to edit SONiC grub option (e.g SONiC-OS-Edgecore-SONiC_20200827_110345_ec201911_2020-aug_enhanced_178)

                             GNU GRUB  version 2.02~beta3

 +----------------------------------------------------------------------------+
 |*SONiC-OS-Edgecore-SONiC_20200827_110345_ec201911_2020-aug_enhanced_178     |
 | ONIE                                                                       |
 |                                                                            |
 |                                                                            |
 |                                                                            |
 |                                                                            |
 |                                                                            | 
 +----------------------------------------------------------------------------+

      Use the ^ and v keys to select which entry is highlighted.          
      Press enter to boot the selected OS, `e' to edit the commands       
      before booting or `c' for a command-line. 

                             GNU GRUB  version 2.02~beta3

 +-----------------------------------------------------------------------------------+
 |setparams 'SONiC-OS-Edgecore-SONiC_20200827_110345_ec201911_2020-aug_enhanced_178' | 
 |                                                                                   |
 |        search --no-floppy --label --set=root SONiC-OS                             |
 |        echo    'Loading SONiC-OS OS kernel ...'                                   |
 |        insmod gzio                                                                |
 |        if [ x = xxen ]; then insmod xzio; insmod lzopio; fi                       |
 |        insmod part_msdos                                                          |
 |        insmod ext2                                                                |
 |        linux   /image-Edgecore-SONiC_20200827_110345_ec201911_2020-aug_enh\       |
 |anced_178/boot/vmlinuz-4.9.0-9-2-amd64 root=UUID=d74a2345-cc22-4cf5-8748-09\       |
 |093333ed93 rw console=tty0 console=ttyS0,115200n8 quiet n\                         |v
 +-----------------------------------------------------------------------------------+


      Minimum Emacs-like screen editing is supported. TAB lists           
      completions. Press Ctrl-x or F10 to boot, Ctrl-c or F2 for          
      a command-line or ESC to discard edits and return to the GRUB menu.   

Step 2: Add init=/bin/bash as shown below, 

 +----------------------------------------------------------------------------+
| insmod gzio                                                                 |^
| if [ x = xxen ]; then insmod xzio; insmod lzopio; fi                        |
| insmod part_msdos                                                           |
| insmod ext2                                                                 |
| linux /image-Edgecore-SONiC_20200827_110345_ec201911_2020-aug_enh\          |
|anced_178/boot/vmlinuz-4.9.0-9-2-amd64 root=UUID=d74a2345-cc22-4cf5-8748-09\ |
|093333ed93 rw console=tty0 console=ttyS0,115200n8 init=/bin/bash quiet n\    |
|et.ifnames=0 biosdevname=0 loop=image-Edgecore-SONiC_202008\                 |
|27_110345_ec201911_2020-aug_enhanced_178/fs.squashfs loopfstype=squashfs \   |
| apparmor=1 security=apparmor varlog_siz\                                    |
|e=4096 usbcore.autosuspend=-1 pcie_aspm=off                                  |
| echo 'Loading SONiC-OS OS initial ramdisk ...'                              |v
+----------------------------------------------------------------------------+

      Minimum Emacs-like screen editing is supported. TAB lists           
      completions. Press Ctrl-x or F10 to boot, Ctrl-c or F2 for          
      a command-line or ESC to discard edits and return to the GRUB menu.  

Note: This insertion will be restored after rebooting. Therefore, it's not necessary to edit grub option again.

Step 3: Press Ctrl+x to boot

Loading SONiC-OS OS kernel ...
Loading SONiC-OS OS initial ramdisk ...
[ 2.708038] irq 16: nobody cared (try booting with the "irqpoll" option)
[ 2.714804] handlers:
[ 2.717210] [<ffffffff94c427b0>] serial8250_interrupt
[ 2.722539] Disabling IRQ #16
[ 3.647833] ixgbe 0000:08:00.1: HW Init failed: -17
bash: cannot set terminal process group (-1): Inappropriate ioctl for device
bash: no job control in this shell
root@(none):/#

Step 4: Now you're able to modify the password by linux command.  Username root as example. 

root@(none):/# passwd root
Enter new UNIX password:
Retype new UNIX password:
passwd: password updated successfully

Step 5: Reboot the switch by linux command or Power cycle the switch

root@(none):/# reboot -f

Reference: SONiC Github https://github.com/Azure/SONiC/blob/master/doc/SONiC-User-Manual.md#23-how-to-reset-password