root pass problem

sud_crow · 2005-06-29 15:10:04

im having a little problem with a centos machine i just set up... i seem to did something wrong when i entered the password, or im just plain stupid and forgot which i entered, either way, i was thinking if its possible to do something about it , at least with a livecd or whatever you can think of.

I just dont want to resintall the whole thing, its a P2 450 and it takes its time to install... but if there is no other way i dont care, as i didnt got to configure anything.

phrakture · 2005-06-29 15:13:20

yeah, boot the liveCD, chroot and use "passwd" to change it 8)

tomk · 2005-06-29 15:39:24

You don't even need the Live CD - boot into single-user mode and sort yourself out.

phrakture · 2005-06-29 15:49:10

tomk wrote:

You don't even need the Live CD - boot into single-user mode and sort yourself out.

really? *writes that down*

tomk · 2005-06-29 15:53:03

No, not really. Sorry everyone - rare sunshine in this neck of the woods has obviously done something to my brain. You need the root password for single-user mode, don't you?! DOH... :oops:

phrakture · 2005-06-29 16:05:16

droog · 2005-06-29 18:55:43

In the "baseball bat" thread, disable root and gain su access, z4ziggy mentioned you can bypass root password with grub single user somehow too. Maybe there is a way. i've read it a couple other places too but cant find them or any details on how.

Mythoz · 2005-06-29 18:55:48

It's very easy to change the root passwd if you have access to the boot manager. Just append "init=/bin/bash" to your boot line. Now you have full root privileges.

Then you must enable write access for the root directory:
# mount -o remount,rw /

Change yor root password
# passwd

Finally rollback and reboot
# mount -o remount,ro /
# sync && sync && sync && sleep 3 && shutdown -r -n now

sud_crow · 2005-06-29 19:16:39

Hi,

Well, im going with phrakture option first, as its the simplest method.

tomk and drug yep, you need root for that.

Mythoz, i dont know if i can dinamically edit GRUB bootloader (that is, during startup), but i know LILO cant be, and to edit it from the running system, i should have root access, which i dont... but i could gain it through a livecd, though i think its easier to chroot in to it.

Gullible Jones · 2005-06-29 19:22:20

Mythoz wrote:

t's very easy to change the root passwd if you have access to the boot manager. Just append "init=/bin/bash" to your boot line. Now you have full root privileges.

But you need root priveleges for that. :?

phrakture · 2005-06-29 19:28:27

Gullible Jones wrote:

Mythoz wrote:
t's very easy to change the root passwd if you have access to the boot manager. Just append "init=/bin/bash" to your boot line. Now you have full root privileges.
But you need root priveleges for that. :?

no you don't - if you're using grub, hit "e" to edit the line before you boot

Gullible Jones · 2005-06-29 19:30:19

D'oh!

(Hmm... That's a local vulnerability! Any way of disabling editing of the boot line from within GRUB?)

Kern · 2005-06-29 19:42:15

you dont need the root password to use "single user" mode.

You do need access to Grub / lilo tho .... anyway, its covered here ....

Howto

and yes, you can password protect the bootloader.
but we are on the way back to "how secure is a pc" type of thread.

edited: typo's an ting

TheDoctor · 2005-06-29 19:50:23

Gullible Jones wrote:

D'oh!
(Hmm... That's a local vulnerability! Any way of disabling editing of the boot line from within GRUB?)

No, that's not a local vulnerability. A local vulnerability would be a user account escalating privelidges. This is considered "Game Over". If an attacker has physical access to your machine, then disabling this would mean nothing. When I forget the root password, I just boot any live distro, mount /dev/hda1 or wherever I can find /etc/, and just edit the passwd file. Hell, you can even do it with an old slack install CD, or a mini distro that you can fit on a credit card sized CD.

Arch Linux

#1 2005-06-29 15:10:04

root pass problem

#2 2005-06-29 15:13:20

Re: root pass problem

#3 2005-06-29 15:39:24

Re: root pass problem

#4 2005-06-29 15:49:10

Re: root pass problem

#5 2005-06-29 15:53:03

Re: root pass problem

#6 2005-06-29 16:05:16

Re: root pass problem

#7 2005-06-29 18:55:43

Re: root pass problem

#8 2005-06-29 18:55:48

Re: root pass problem

#9 2005-06-29 19:16:39

Re: root pass problem

#10 2005-06-29 19:22:20

Re: root pass problem

#11 2005-06-29 19:28:27

Re: root pass problem

#12 2005-06-29 19:30:19

Re: root pass problem

#13 2005-06-29 19:42:15

Re: root pass problem

#14 2005-06-29 19:50:23

Re: root pass problem

Board footer