How To Set A Password For Grub At Boot Time in linux

http://funlinuxfun.blogspot.com/
Grub is the linux default bootloader.

Setting up a password in grub is quite an easy task.you can set the password just at boot time to prevent anyone from logging into the system in any mode.

here is how to do it.

Enter the command line and type

#grub-md5-crypt

you will be prompted to enter the password..after entering the password twice you will be provided with a encrypted value as shown below..

copy this encrypted value.

now open the grub.conf file.

#vi /boot/grub/grub.conf

and enter the line

passwd   –md5    $1$Tqro5/$pkEbG8f4igg0oZRCoWznb1

where the above encrpted value is the one generated at the time when you entered the password.

also enter

lock

at the end of the red hat container as shown in the figure below.

come out of the editor and then reboot.

#init 6

now at startup you will be asked for the password.

press ‘p’ for password.

and enter the password.

How to Break root password in redhat/linux

http://funlinuxfun.blogspot.com/
Root account in linux is the supreme account holding all the privildges to manage and configure  your system.

Sometimes non-root users wish to login into the root account but doesn’t have the password or in times some bad users change the root password which disables root-user to login ,hence he need to change the password for his account  and setup a new password

Here are the all steps to change/break  password for root in linux even if previous password is not known:

Step 1:)

When the first  grub screen like the below snapshot appears  press ‘e’ on linux line entry:

Step2)

After preesing “e” in the previous step the snapshot similar to the below snapshot appears. Move to the line which contains the word ‘kernel’ and  press  ‘e’

Step3)

Go to end of that line and after rhgb quiet write  1 as in the snapshot below…this means that you are setting your kernel to boot into single user mode also known as the maintenance mode.

Step4)

Then press “enter ” and then  ‘b’ to boot the system into run level 1:
Step5)

Now wait for the prompt and  write the following command :
#passwd root

Now the password for root account has been changed and try login with the new account: