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Darren Jacobs

2007-Oct-30 15:32 UTC

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

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?





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Steven Timm

2007-Oct-30 15:35 UTC

head link

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

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@fnal.gov  http://home.fnal.gov/~timm/
Fermilab Computing Division, Scientific Computing Facilities,
Grid Facilities Department, FermiGrid Services Group, Assistant Group Leader.

_______________________________________________
Xen-users mailing list
Xen-users@lists.xensource.com
http://lists.xensource.com/xen-users

Nico Kadel-Garcia

2007-Oct-30 15:49 UTC

head link

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

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. Why? Can''t you shut down the DomU, mount the DomU''s
"/" partitin, do a
chroot to it, and edit it from the Dom0?

If not, you should be able to use "xm create -c domain" to get the
grub
console and boot into single user mode, unless you''ve been very fascist
about your grub configuration.
> 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:See, this is where you should use "xm create -c
''DOMAIN''"


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Liam Kirsher

2007-Oct-30 17:50 UTC

head link

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

Steven, why do you write "being sure to fsck it afterwards" ? Is that
important?
The reason I ask is that I had a domU filesystem get corrupted, and I
don''t know how it happened.
It was not all that important in that it was easy to recreate, being
just my stock CentOS 5 template + bind.
But, just the same, I''d like to know how it happened!  Interestingly,
Xen never had a problem creating the domU.  However, my attempts to
mount it (after shutting down the domU) failed because mount couldn''t
find a valid ext3 filesystem.  Eventually I found a valid superblock,
but virtually all the files ended up in lost+found.

Steven Timm wrote:> 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?
>>
>>
>>
>
-- 
Liam Kirsher
PGP: http://liam.numenet.com/pgp/


_______________________________________________
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Xen-users@lists.xensource.com
http://lists.xensource.com/xen-users

Steven Timm

2007-Oct-30 18:09 UTC

head link

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

On Tue, 30 Oct 2007, Liam Kirsher wrote:
> Steven, why do you write "being sure to fsck it afterwards" ? Is
that
> important?
I don''t have much experience with Xen but I did see an
error like you described below, and after making it a point
to fsck domU file systems after I unmounted them from dom0
I haven''t seen the problem again.

Steve Timm

> The reason I ask is that I had a domU filesystem get corrupted, and I
> don''t know how it happened.
> It was not all that important in that it was easy to recreate, being
> just my stock CentOS 5 template + bind.
> But, just the same, I''d like to know how it happened! 
Interestingly,
> Xen never had a problem creating the domU.  However, my attempts to
> mount it (after shutting down the domU) failed because mount
couldn''t
> find a valid ext3 filesystem.  Eventually I found a valid superblock,
> but virtually all the files ended up in lost+found.
>
> Steven Timm wrote:
>> 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@fnal.gov  http://home.fnal.gov/~timm/
Fermilab Computing Division, Scientific Computing Facilities,
Grid Facilities Department, FermiGrid Services Group, Assistant Group Leader.

_______________________________________________
Xen-users mailing list
Xen-users@lists.xensource.com
http://lists.xensource.com/xen-users

Darren Jacobs

2007-Oct-30 20:54 UTC

head link

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

That worked.  Thanks Steve.  It was just too straight forward for me  
to think of :'')



On 30-Oct-07, at 11:35 AM, Steven Timm wrote:
> 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@fnal.gov  http://home.fnal.gov/~timm/
> Fermilab Computing Division, Scientific Computing Facilities,
> Grid Facilities Department, FermiGrid Services Group, Assistant  
> Group Leader.

_______________________________________________
Xen-users mailing list
Xen-users@lists.xensource.com
http://lists.xensource.com/xen-users

Nico Kadel-Garcia

2007-Oct-30 21:12 UTC

head link

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

Steven Timm wrote:> On Tue, 30 Oct 2007, Liam Kirsher wrote:
>
>> Steven, why do you write "being sure to fsck it afterwards" ?
Is that
>> important?
>
> I don''t have much experience with Xen but I did see an
> error like you described below, and after making it a point
> to fsck domU file systems after I unmounted them from dom0
> I haven''t seen the problem again.
>
> Steve TimmIt''s a belt and suspenders tactic from the older days of filesystems, 
when fsck was part of every reboot and when booting form CD didn''t 
exist. It can''t hurt, and it can help prevent a really laborious fsck
at
boot time when no one is around to type the root password at the console.

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Xen users - Oct 2007 - resetting lost root password on a xen guest

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

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

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

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

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

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

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