In this tutorial we will learn,recover Linux Grub Password in linux rescue mode CentOS/Red Hat.We are doing this practical with scenario,in case we forgot root as well as grub password.The method will help you to recover linux grub boot loader password.
Requirement: We prefer to use bootable CentOS/Red Hat CD/DVD/USB which is used for installing Operating System.
Recently, we have already published about two posts,we suggest you to also read these posts:
Follow the given below steps to recover linux grub password
Step 1: Get the CentOS/Red Hat bootable CD/DVD/USB media.And insert the media into system.It is obvious for CD/DVD use CD/DVD ROM and for USB devices use USB port in system.
Step 2: On booting you will see some options on screen.Use any one method given below:
Select “Rescue installed system” and hit enter.
Alternatively, you can also press TAB key and add the word “linux rescue” and hit enter.
See the screenshot of both method. Do not worry, after this all steps are same.
Step 2: Now choose the language as you have in Operating system. I have selected english.
Step 3: Select your keyboard type
Step 4: Now you will see “Setup Networking” screen.It is optional,as per your requirement select Yes or No. I have selected yes.
Step 5: Because we have selected Networking Yes. Now select which interface you want to enable.
Step 6: In “Enable Network Interface” screen.Either you can select DHCP or static. If you have IPV6 in your network, you can also select that option. In static option,give the IP information as you have.
Step 7: Now you will get “Rescue” screen. Now the rescue environment will mount your operating system in /mnt/sysimage. It means we can find our grub.conf file in /mnt/sysimage ,once we get into rescue environment shell
Note: If you do not select networking in Step 4,you will directly see this screen.
Step 8: In next screen,you will get the message,”The system has been mounted under /mnt/sysimage” . Select OK.
Step 9: Now select shell and OK. See the given below screenshot.
Step 10: In given screenshot, I have run two commands to show who is current user login and where the system filesystem has been mounted.
Hence,the user is root and we can see the boot is mounted under /mnt/sysimage/boot .
Step 11: Important note here,in this practical I have used the command
chroot /mnt/sysimage. You can run this command.It helps to reboot the system when you hit
exit command . If you do not run
chroot /mnt/sysimage command then when you hit exit command,you will be back to previous screen (as we have seen a step ago) and after this you have to select reboot option to restart the system.
Here, I have not used
chroot /mnt/sysimage command.So that I could show you ,how it looks and what happen.So do not get confuse over here.
Step 12: Now we are editing the grub.conf file where we can find the grub password has been set.
Edit the grub.conf file
Run the below command as given in screenshot.
Search the line have written something,
password --md5 some-encrypted-password. Comment or remove this line from grub.conf file.
See in our screenshot,I have commented the line.
Step 13: After saving the file ,now reboot the system,run the command.
Step 14: If you have not run the command
chroot /mnt/sysimage before editing the grub.conf. You will be back to given below screen.If yes,now select Reboot and then OK
REMOVE your installation media at the time of reboot,otherwise it will again go to O.S installation screen
Now on booting of system,you will not see grub password.If yes,practical is completed.