root authentication failure

[DrElie]

hello again.

just trying to configure debian, its just that i added two users that suppose in it and now root cannot login anymore?! what happen? what should i do to be able to login as root again. by the way i am using command line interface only.

Thanks.

[atreyu]

Can you show the commands you used to add the users?

Can you log in as a regular user still? If so, can you su up to root?

You can reboot into runlevel 1 to change root's password, if you need to, but that should wait until you've figured out what happened.

[DrElie]

yes i can log-in with a different user but when i do su and put password it will stay say authentication failure, i can't even use sudo, it will respond -sh: sudo: not found. the thing is i was working just fine until i added two users and tried logging in with it. what's the other way to resolve this problem? I really appreciate your response...

[DrElie]

i used useradd command.

[atreyu]

Very strange! Does anybody else have these user accounts? I.e. could someone else have logged in and changed root pw?

Anyway, you can reboot into runlevel 1 and change the password again.

Reboot and at the grub/boot prompt, hit the [Tab] key to interrupt the boot process.

Then highlight your kernel of choice and hit the [a] key to append to the kernel boot arguments.

Then enter ' 1' at the end of the arguments and hit [Enter] to boot into runlevel 1 (text-only, no GUI, services, networking, etc.).

After a few seconds of kernel messages, it should drop you to a console (bash) prompt. You can just type 'passwd' to change the root password. As soon as you've done it, try logging in with it, by first su-ing to a regular user, then su-ing to root.

[DrElie]

actually i've been trying to do just that but the thing is when i hit [Tab] at the grub/boot prompt nothing is happening...
when you said grub/boot prompt you mean the display is like

Debian GNU/Linux, with Linux 2.6.32-5-686
Debian GNU/Linux, with Linux 2.6.32-5-686 (recovery mode)
press enter to boot selected os, 'e' to edit or 'c' for a command line.

?
is this what you meant?

[atreyu]

Yes, that's the menu I mean. Sorry, I don't use Debian often so I'm not familiar with the subtle differences that are obviously present. Maybe the "recovery mode" is the same thing as runlevel 1. Press 'e' to edit it and see if ' 1' or ' s' is at the end of the line. In that case, that's what you want. Otherwise, you should be able to use 'e' to edit the kernel entry of the first one and add the ' 1'. If I'm mistaken, hopefully a Debian guru will step in and shed some light.

[DrElie]

i tried the recovery mode and it ask me for root password for maintenance
and there is another option to continue but still it would ask for a user and password
I tried e but can't find 1 or s and tried i just tried adding it in the last line but nothing change

[atreyu]

okay...hmm, reboot and edit the first kernel entry, and try adding " init=/bin/sh" to the kernel command line.

See this article.

[DrElie]

indeed in Debian GNU/Linux 6, the recovery mode is the single user mode, but it would still require the root password to get into it. it would ask root password or press control d to continue but if you choose the latter, it will boot to the default run level. tried modifying the /etc/inittab to put runlevel 1 as default, it would say that the file is read only. with the working user account, i can't even sudo Thanks anyway.