"Unfortunately"

saranrajk · 07-06-2008, 11:52 PM

im using RHEL4 unfortunately i deleted root user and its password.Can anyone pls help me to create root at the time of OS booting?

indeliblestamp · 07-07-2008, 12:51 AM

Hmm, I'd recommend booting with a LiveCD and mounting your root parition. Chroot into it, and you might get a prompt that says 'I have no name!'. The steps are:

Code:

mkdir /tmp/temproot
mount /dev/sda1 /tmp/temproot (where sda1 is where your / partition is installed)
chroot /tmp/temproot

Edit /etc/passwd and add a line on top like this (or make sure it exists):

Code:

root:x:0:0:root:/root:/bin/bash

Chroot in again and hit 'passwd root' and you should be able to set a new password for root now.
I've done this when I've lost root password but not when the root user itself has been deleted. But these steps should work by and large.

Vit77 · 07-07-2008, 01:25 AM

How have you done it? Just removed these lines from files passwd and shadows? Or may be disabled it?
If you can boot in single user mode, it'll be possible to edit them again, or use command useradd.

If not, it could be recommended to reinstall the system. Especially, if you have made some other mistakes like that.
I suppose, there is no critical information on the box?

pixellany · 07-07-2008, 02:13 PM

Another solution:
Boot into "single-user" mode.

When the GRUB menu appears, hit any key to stop the countdown, "e" for edit, then select the kernel line and "e" for edit again. Add the work "single" (no quotes) at the end of the line, and then boot. You will be logged in as the root user with no password needed. Then set your password using the "passwd" command, and re-boot.

JZL240I-U · 07-09-2008, 01:32 AM

Quote:

Originally Posted by pixellany

...You will be logged in as the root user with no password needed...

I didn't try this, but that looks like a wide open door to capture a system. Getting logged in as root with no password needed ... isn't that the dream of every hacker in existence? What am I overlooking?

indeliblestamp · 07-09-2008, 02:07 AM

Quote:

Originally Posted by JZL240I-U

What am I overlooking?

I guess its the fact that you need physical access to the machine if you want to switch runlevels at boot time. If a bad guy is sitting in your house or office server room, your data is pretty much completely compromised anyway (he could just take the hard disk out, for instance).

JZL240I-U · 07-09-2008, 02:28 AM

Quote:

Originally Posted by arungoodboy

...If a bad guy is sitting in your house or office server room...

Sure. But it also means any user in a firm can become root (if (s)he has physical access -- but nobody controls all situations). This is no problem for me, but were I administrator I think I'd like to disable that "feature".

indeliblestamp · 07-09-2008, 02:37 AM

Ya that's true. I dunno about Lilo but I think you can set a password in grub to prevent random people from fiddling with boot time arguments. Now if you forget that password too..

AceofSpades19 · 07-09-2008, 02:47 AM

Quote:

Originally Posted by JZL240I-U

Sure. But it also means any user in a firm can become root (if (s)he has physical access -- but nobody controls all situations). This is no problem for me, but were I administrator I think I'd like to disable that "feature".

Thats why you only let certain people in the server room and/or have a bootloader password

JZL240I-U · 07-09-2008, 04:07 AM

Quote:

Originally Posted by AceofSpades19

...have a bootloader password

That's an acceptable solution

. There may always be situations, where access to the server room is not as restricted as designed, but a password for GRUB -- fine. Thanks all.

mrrangerman · 07-09-2008, 06:09 AM

Quote:

pixellany

Another solution: Boot into "single-user" mode.
When the GRUB menu appears, hit any key to stop the countdown, "e" for edit, then select the kernel line and "e" for edit again. Add the work "single" (no quotes) at the end of the line, and then boot. You will be logged in as the root user with no password needed. Then set your password using the "passwd" command, and re-boot.

This may work for the Ubuntu's (haven't tried it yet) but I know on my Debian systems I am still prompt for a root passwd or Ctrl + D to continue.

trickykid · 07-09-2008, 09:17 AM

Quote:

Originally Posted by pixellany

Another solution:
Boot into "single-user" mode.

When the GRUB menu appears, hit any key to stop the countdown, "e" for edit, then select the kernel line and "e" for edit again. Add the work "single" (no quotes) at the end of the line, and then boot. You will be logged in as the root user with no password needed. Then set your password using the "passwd" command, and re-boot.

Usually by default on RHEL, single user will prompt for root's password, added security so people can't login when they have physical access to gain root access.

The other way around this is to boot by adding this to the grub line: init=/bin/bash

Instead of using single user mode.

shridhar005 · 07-14-2008, 02:08 PM

Please give appropriate name to your thread.