02.11.04
 By
A.P. Lawrence
I have a very good memory. I remember most of my client's passwords
(there are a few I forget regularly for no reason that I can understand,
but I really do know most), I remember telephone numbers, and of
course I know my own passwords. That last isn't as easy as it might
sound, because I have quite a few different systems and each has
its own password, but though I might use the wrong one now and then,
I'll get it on the second or third try.
Well, not this time. A while back I installed Fedora on a system here,
and today I wanted to look at something and .. what was the root password?
Hmm, not that.. how about? .. nope, well it must be.. darn! |
I
had no idea. Fortunately, it wasn't a boot password, so I did have
access to the system. Without that, I would have had to dig up the
CD's (who knows where they are) and do a recovery that way, or download
something from Tom's Root and Boot Site. I had access to the Grub
loader, so I had it easy.
If you've lost your root password, you might be able to do it this
way. However, some systems are protected with boot loader passwords
that won't let you do that without THAT password. If the boot loader
is password protected, you need to boot from other media - for newer
systems, the install CD probably has the recovery tools for that.
But let's try it the easy way first. The first thing to try is to
boot to single user mode. This MIGHT not work for you, because your
system might be configured to still ask for a root password to get
to single user mode. If that's the case, we'll use another trick that
replaces init with /bin/bash.
First, try single user. If you don't see either a LILO or GRUB boot
screen, try hitting CTRL-X to get one. If it's LILO, just type "linux
single" and that should do it (assuming that "linux" is the lilo label).
If GRUB, hit 'e", then select the "kernel" line, hit "e" again, and
add " single" (or just " 1") to the end of the line. Press ENTER,
and then "b" to boot.
You
should get a fairly normal looking boot sequence except that it terminates
a little early at a bash prompt. If you get a "Give root password
for system maintenance", this isn't going to work, so see the "init"
version below.
If you do get the prompt, the / filesystem may not be mounted rw (although
"mount" may say it is). Do
mount -o remount,rw /
If that doesn't work (it might not), just type "mount" to find out
where "/" is mounted. Let's say it is on /dev/sda2. You'd then type:
mount -o remount,rw /dev/sda2
If you can do this, just type "passwd" once you are in and change
it to whatever you like. Or just edit /etc/shadow to remove the password
field: move to just beyond the first ":" and remove everything up
to the next ":". With vi, that would be "/:" to move to the first
":", space bar once, then "d/:" and ENTER. You'll get a warning about
changing a read-only file; that's normal. Before you do this, /etc/shadow
might look like:
root:$1$8NFmV6tr$rT.INHxDBWn1VvU5gjGzi/:12209:0:99999:7:-1:-1:1074970543
bin:*:12187:0:99999:7:::
daemon:*:12187:0:99999:7:::
adm:*:12187:0:99999:7:::
and after, the first few lines should be:
root::12209:0:99999:7:-1:-1:1074970543
bin:*:12187:0:99999:7:::
daemon:*:12187:0:99999:7:::
adm:*:12187:0:99999:7:::
You'll
need to force the write: with vi, ":wq!". (If that still doesn't work,
you needed to do the -o remount,rw, see above).
Another trick is to add "init=/bin/bash" (LILO "linux init=/bin/bash"
or add it to the Grub "kernel" line). This will dump you to a bash
prompt much earlier than single user mode, and a lot less has been
initialized, mounted, etc. You'll definitely need the "-o remount,rw"
here. Also note that other filesystems aren't mounted at all, so you
may need to mount them manually if you need them. Look in /etc/fstab
for the device names.
See also
http://aplawrence.com/Bofcusm/861.html
http://aplawrence.com/Bofcusm/872.html
http://aplawrence.com/Bofcusm/873.html
About the Author:
A.P. Lawrence provides SCO Unix and Linux consulting services http://www.pcunix.com
Read this newsletter at: http://www.linuxpronews.com/2004/0211.html |
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| From the Forum: | | New to datebases | | hey guys i just got a job for this company signdesigns.com they are a located near my college and i will be going there between classes to help them out with their web site as you can see right now its in need of help BIG TIME! well i have made a basic layout here mxtracks.us/signdesigns i was wondering if i were to add a database that would have info about all the customers and it would have info on how far they are into the job stuff like that how the hell would i do this? ... |
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