topic Cannot Login as any user including Root in Operating System - Linux

Cannot Login as any user including Root

Jason Shannon — Wed, 30 Apr 2008 09:26:23 GMT

I have a Proliant machine running RH4.
I have just ran up2date on the installation to bring it to RH4 Update 4.

The update seemed to work fine and upon reboot all services look to have started.

The issue i have now is that at the login GUI, i try to login in as root and receive a popup message saying "Authentication Failed". If i try to login as any other user or enter the wrong root password in i get the usual Invalid Username/Password message.

Any help is greatly appreciated.

Re: Cannot Login as any user including Root

Alexander Chuzhoy — Wed, 30 Apr 2008 09:33:10 GMT

Do you also get a message for some missing librarires or just authentication?
If it's just authentication - the boot your station into init 1 see what happens.
Do you use authentication services or all accounts were local?

Re: Cannot Login as any user including Root

Jason Shannon — Wed, 30 Apr 2008 09:38:25 GMT

We just authenticate locally.

I get no errors regarding missing libraries - just the pop up saying 'Authentication Failed'

Re: Cannot Login as any user including Root

Matti_Kurkela — Wed, 30 Apr 2008 09:39:19 GMT

Are you using the default passwd-file-based authentication, or something more complex like NIS or LDAP?

You may have to reboot using the login GUI's reboot option (if it has one) or by pressing Ctrl-Alt-Del on the console. Both these methods should cause an immediate reboot in a controlled fashion if the system is in default configuration.

When you get to the bootloader screen, interrupt the automatic boot (press any key).
You now have several possible ways to go on:

- boot to single user bypassing any authentications by using boot option "init=/bin/bash". NOTE: if you use this approach, remember to mount the root filesystem in read/write mode before trying to change anything.

- boot from RedHat installation CD using the "rescue" option. This is a more user-friendly way to regain access to the system. The rescue mode should automatically detect the installed system and mount it as a sub-tree of the installation/rescue environment. You can then examine (and if necessary, change) any configuration files.

MK

Re: Cannot Login as any user including Root

Jason Shannon — Wed, 30 Apr 2008 09:46:54 GMT

We are just using password file authentication.

I intend using the rescue cd and doing as you suggested. Do you have any idea what the files are I should be looking at?

Thanks

Re: Cannot Login as any user including Root

Trever Furnish — Thu, 01 May 2008 12:35:02 GMT

If you have ssh to the system allowed, check whether you can log in using ssh.

If not, try switching to a non-GUI virtual terminal. X usually runs on virtual console 7, so if you're at the console and you press control-alt-F1 (as in the function key, F1) you'll get switched to virtual console 1 and have a simple non-graphical login prompt. I suggest this because your problem could affect only GDM (the graphical login system).

As for what files to look at if you reboot, I'd suggest doing an updatedb followed by 'locate rpmsave; locate rpmnew'. Also see /var/log/messages and /var/log/secure and any other files recently updated in /var/log (hint: ls -ltr /var/log and work backwards).

The authentication and authorization processes for all services are controlled by the files in /etc/pam*, so changes (if there were any) could also cause such symptoms.

Of course none of this would be *expected* as a result of a sucessful run of up2date...

Re: Cannot Login as any user including Root

Jeeshan — Fri, 02 May 2008 04:26:56 GMT

Hi Jason

Check the file in /etc/pam.d/login. this is for authentication.