Fedora 16 grub password problem

axel2078 · #1 11th April 2012, 05:11 AM

I just installed Fedora 16 on my laptop a short while ago. During the installation when it gives you the option to set a password for grub, I checked the box and gave it a password. I noticed a few minutes ago that when I try to edit the kernel parameters during the grub stage, it asks me for a username and then a password. When I set this up, it never asked me for a username. I've tried my username with my password and I've tried root with it's password, but neither work. What's going on here?

Dutchy · #2 11th April 2012, 09:45 AM

I don't know about the default grub user that anaconda creates, but my manually created grub user is revealed by the following command:

Code:

cat /etc/grub.d/00_header | grep user

marriedto51 · #3 11th April 2012, 10:47 AM

I think that anaconda generates a user for grub with name 'root'; I can't remember whether you get chance to set a specific password or whether it just picks up the system root password.

Also, beware that the keymap at the grub screen is the default US keyboard layout, which might differ from the layout you expect to use. (I only mention this because that trips me up: I'm used to the UK layout which has various punctuation symbols in different places, including some that I use in passwords!)

axel2078 · #4 11th April 2012, 03:22 PM

Quote:

Originally Posted by marriedto51

I think that anaconda generates a user for grub with name 'root'; I can't remember whether you get chance to set a specific password or whether it just picks up the system root password.

Also, beware that the keymap at the grub screen is the default US keyboard layout, which might differ from the layout you expect to use. (I only mention this because that trips me up: I'm used to the UK layout which has various punctuation symbols in different places, including some that I use in passwords!)

I thought this might be the case, so I tried using root as the user and the password that I set up for root during the account creation, but it didn't work. Now that I think about it, I created a different password for grub during the installation than I used for root's password. Last night I was trying my account with my password and root's account with root's password, but I didn't try using root as the username with the password that I set for grub. I wonder if that would work?

---------- Post added at 09:22 AM ---------- Previous post was at 07:59 AM ----------

On a side note, if trying root as the username with the password I set for grub (not root) doesn't work, how can I recover grub so that it's no longer password protected?

marriedto51 · #5 11th April 2012, 04:31 PM

Quote:

Originally Posted by axel2078

On a side note, if trying root as the username with the password I set for grub (not root) doesn't work, how can I recover grub so that it's no longer password protected?

The quick and easy way is to edit the file /boot/grub2/grub.cfg and comment out (with '#' characters) or remove the lines that look like

Code:

set superusers="root"
password_pbkdf2 root grub.pbkdf2.sha512.on-and-on-and-on-and-...

You can alternatively edit the file /etc/grub.d/01_users, and then run the command

Code:

grub2-mkconfig -o /boot/grub2/grub.cfg

(as root).

axel2078 · #6 11th April 2012, 06:09 PM

Quote:

Originally Posted by marriedto51

The quick and easy way is to edit the file /boot/grub2/grub.cfg and comment out (with '#' characters) or remove the lines that look like

Code:

set superusers="root"
password_pbkdf2 root grub.pbkdf2.sha512.on-and-on-and-on-and-...

I actually tried this last night (commented out only the password line), but I didn't use the command to rebuilt grub afterward before I rebooted. Was I supposed to? There was no change once my system rebooted.

marriedto51 · #7 11th April 2012, 08:01 PM

If you edited /boot/grub2/grub.cfg, you should not need to do anything else to see the change.

If you edit the files in /etc/grub.d, or change /etc/default/grub, then you need to run grub2-mkconfig before you see the change(s).

Make sure you remove the "set superusers" line as well as the password line: then the grub command line should be available to anyone.

axel2078 · #8 12th April 2012, 02:42 AM

Quote:

Originally Posted by marriedto51

If you edited /boot/grub2/grub.cfg, you should not need to do anything else to see the change.

If you edit the files in /etc/grub.d, or change /etc/default/grub, then you need to run grub2-mkconfig before you see the change(s).

Make sure you remove the "set superusers" line as well as the password line: then the grub command line should be available to anyone.

Thanks a lot for the info. I'll try this later and post my results.

---------- Post added at 08:42 PM ---------- Previous post was at 02:04 PM ----------

UPDATE: It seems my earlier theory was correct. Although the Anaconda installer didn't tell you it was creating a user account when you opt to password protect grub, it did; it created an account called root. The password I provided for grub was different than the password I supplied when the root account was created. That's what tripped me up. When I tried to edit the boot menu and grub asked me for a username, I tried my username with my password and root with root's password, but what I needed was the username root with grub's password.