Re: [Xen-users] resetting lost root password on a xen guest

[Steven Timm <timm@xxxxxxxx>]

Darren--can you temporarily stop the xen guest and mount
its root FS from dom0? if so, then just zero out the root passwd
and shadow entry from there, unmount the client rootfs, being
sure to fsck it afterwards, then start up the client again.

Steve


On Tue, 30 Oct 2007, Darren Jacobs wrote:

> Hi All,
>
> I need to get into a xenguest running linux for which the root password has 
> been lost.  I'm running xen 3.0.3 under RH 5.
> I'm trying to figure out how to get pygrub for this guest to load up the 
> typical "init=/bin/sh" to get the console to come up at the command line 
> prompt so I can reset the root password.
> Trolling though google I've see suggestions to add args = 'init=/bin/sh' or 
> opts = 'init=/bin/sh' to the guest configuration file.  None of them appeared 
> to have worked.  If I do a 'xen create echo11 -n' after making any of the 
> above file mods I see that the args were not modified:
> --
> (vm
>   (name echo11)
>   (memory 500)
>   (on_reboot restart)
>   (on_crash restart)
>   (vcpus 1)
>   (uuid cb855323-2867-b84a-d766-32a39d252bb7)
>   (bootloader /usr/bin/pygrub)
>   (image
>       (linux
>           (ramdisk /var/lib/xen/initrd.kIQYUw)
>           (kernel /var/lib/xen/vmlinuz.Xwl81-)
>           (args 'ro root=/dev/VolGroup00/LogVol00')
>       )
>   )
>   (device
>       (tap (uname tap:aio:/var/lib/xen/images/echo11) (dev xvda) (mode w))
>   )
>   (device (vif (bridge xenbr0) (mac 00:16:3e:69:69:90)))
> --
>
> So I tried to bring the guest up manually from dom0 with " pygrub 
> /var/lib/xen/images/echo11.dsk".  When the menu comes up I edit the kernel 
> line directly and insert "init=/bin/sh".  You can see below that the init 
> statement was indeed read:
> --
> [root@dom0 xen]# pygrub /var/lib/xen/images/echo11
> Going to boot Fedora (2.6.20-2925.13.fc7xen)
> kernel: /vmlinuz-2.6.20-2925.13.fc7xen
> initrd: /initrd-2.6.20-2925.13.fc7xen.img
> linux (kernel /var/lib/xen/vmlinuz.pBqWti)(ramdisk 
> /var/lib/xen/initrd.9IdU7X)(args 'ro root=/dev/VolGroup00/LogVol00 
> init=/bin/bash')
> [root@dom0 xen]#
> --
>
> However the guest did not start up :'(  Its starts just fine if I issue a "xm 
> create echo11".  Any suggestions on where to look from here?
--
------------------------------------------------------------------
Steven C. Timm, Ph.D  (630) 840-8525
timm@xxxxxxxx  http://home.fnal.gov/~timm/
Fermilab Computing Division, Scientific Computing Facilities,
Grid Facilities Department, FermiGrid Services Group, Assistant Group Leader.

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