Hey !!!
On Thursday 03 February 2011 20:42 Robert Heller wrote
> At Thu, 3 Feb 2011 20:12:17 +0100 CentOS mailing list <centos@xxxxxxxxxx>
wrote:
> > Hi :)
> >
> > On Thursday 03 February 2011 14:59 Giles Coochey wrote
> >
> > > On 03/02/2011 14:40, Rafa Griman wrote:
> > > > Hi :)
> > > >
> > > > On Wed, Feb 2, 2011 at 3:44 PM, James Bensley<jwbensley@xxxxxxxxx>
wrote:
> > > >> So on a virtual server the root password was no longer working (as
> > > >> in I couldn't ssh in anymore). Only I and one other know it and
> > > >> neither of us have changed it. No other account had the correct
> > > >> privileges to correct this so I'm wondering, if I had mounted that
> > > >> vdi as a secondary device on another VM, browsed the file system
> > > >> and delete /etc/shadow would this have wiped all users passwords
> > > >> meaning I could regain access again?
> > > >>
> > > >> (This is past tense because its sorted now but I'm curious if this
> > > >> would have worked? And if not, what could I have done?).
> > > >
> > > > As the other said: DON'T delete /etc/shadow.
> > > >
> > > > Someone also mentioned you could modify the hash in /etc/shadow. This
> > > > will work if you are root or have the right permissions with sudo.
> > > >
> > > > If you can reboot the system, what really works great is passing the
> > > > following option to the kernel on the lilo/grub screen when the
> > > > system
> > > >
> > > > boots:
> > > > init=/bin/bash
> > > >
> > > > This will give you a shell without being asked for a password (unless
> > > > the sys admin has done his homework ;) Now that you have shell access
> > > >
> > > > ... you are in charge so you can:
> > > > - mount the / partition and chroot
> > > >
> > > > - edit /etc/shadow and delete the password hash
> > > >
> > > > - whatever you can imagine ... you decide ;)
> > >
> > > That would do it... There is single-user-mode (runlevel 1), just add
> > > the word single to the kernel parameters line before bootup
> > >
> > > It will give you the same result and mount stuff without the need to
> > > chroot etc...
> >
> > Yes, but S|Single|1 asks for root password to login ... And he doesn't
> > have the root password ;)
>
> RedHat / RHEL / CentOS does not do that!
True, just tried it with RHEL 6 and CentOS 5.3. Well it should ask for a
passwd ... at least IMHO.
Then again ... an admin should configure grub/lilo to ask for a password if you
pass parameters to the kernel during boot time :)
> At least never on any of my
> machines -- is there some config option for that? Yes, for manual fchk
> it does, but not otherwise.
I'll check, but no idea.
Rafa
--
"We cannot treat computers as Humans. Computers need love."
Happily using KDE 4.5.5 :)
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