What if linux forgets the root password and grub Password?

When we forget the root password, if GRUB does not set a password or knows the GRUB Password, we can use a single user method to change the password. This means we have to use a CD to change the root password.

1. Place the system disc into the optical drive and set the Boot Mode of the optical drive.

2. Select F2 to go to system repair. Enter the command: linux rescue.

3. the options below are the same as those when installing the system.

4. Remember when this prompt appears,The prompt command:

# Chroot/mnt/sysimage

5. The next step is to change the password. We should first:

# Chroot/mnt/sysimage # You cannot enter the writable mode.

6. Run the command passwd.

New Password
Confirm New Password

7. restart the computer.

How to encrypt grub: There are two types of grub passwords: plaintext and MD5.
Plaintext encryption: edit the grub. conf file
Vim/boor/grub. conf add a line of password = 1234567890 Under default = 0 (this is the plaintext password)

MD5 encryption: commands are required first.

# Grub-md5-crypt

Calculate the MD5 value and copy the value to the grub. conf file.

Password -- md5 $ BYxEn $ e5X/xOTS2pTpPPWtgIMhU1 (this is the value encrypted with MD5)