Help required

Pallav Jain b330bkn at
Fri Jun 11 12:09:37 UTC 2010

If that is the password for only Grub at the booting, does it guarantee the
security of the hard-disk? becoz the login has been restricted. i am new so
don't know much about stdout, would see it.  your later, lines, i am not
able to understand, my request to you would be if you could make it more
simple for a new user like Tim did.


---------- Forwarded message ----------
From: kalinix <calin.kalinix.cosma at>
To: Community support for Fedora users <users at>
Date: Thu, 10 Jun 2010 22:28:15 +0300
Subject: Re: Re: Help required
On Fri, 2010-06-11 at 00:21 +0530, Pallav Jain wrote:

thx tim, your method is too good for securing the data. but i have som
doubts which are as follows:

as you mentioned, i did, but frankly speaking, i am new user, so facing much
problem. the issues are as follows:

1. i edited the grub.conf file, by adding in it the line:

password --md5 $xxx/

just above the first title section and below 'hiddenmenu' line. (where
xxx=Envrypted password)

but is this encrypted password of the general user that i login with, in the
fedora system? and not the root ever?

Not at all, this password is ONLY for accessing and editing Grub on boot

2. when we get the encrypted password while typing the command 'md5crypt' in
the grub shell, where is this saved? i mean if at all after closing we want
to see this encrypted password where to see? and each time if typing the
'md5crpty' command in the grub shell overwrites the previous password?

 Generally speaking, the output of any command is stdout. What gets os
stdout is not saved anywhere, unless directed so (through a pipe or a
redirect for example).
And yes, unless you use same salt for md5 generated hashes or you do not use
salt at all, the hash will differ from one command to another. On the other
side, the command in the grub shell does not overwrites anything, while you
have to manually copy the hash and paste it in the grub file.

 3. if we even encypt the password of the root, method is same? if yes, how
to enter the username 'root' so that the sys. understands this is the
encrypted password of 'root' only.

No. The <emphasize> SHA256 hash </emphasize> for root's (or any other user)
password is kept in /etc/shadow. When root logs in, the login generates an
hash out of the password entered on the terminal and it's compared with the
one existing in /etc/shadow. If those two matches, the access is granted.
(of course this is the simpler way to put it, in fact things can become much
more complicated)

 4. as you say:

"And then.... if you want different passwords for different menu items,
put the password line within the different title sections of the
grub.conf file, instead of having one password line above all of them.",

means that each encrypted password is to be obtained from the grub shell
only, by typing that particular password? and it is saved where?

The passwords Tim was talking about are ONLY FOR grub menu, and again it's
not saved anywhere. As I said above, the stdout is not saved, unless you
construct your command for saving stdout. Grub access password and login
password are ENTIRELY two different things.

 thanks man.



As has been mentioned before, "/etc/grub.conf" "/boot/grub/grub.conf"
and "/boot/grub/menu.lst" are all the same thing.  One is the actual
file, the others are links to it.  You can work on any of them, it works
the same.

If you're trying to put an encrypted password into GRUB, so that only an
authorised person can do something with it, then follow the steps on the
page, carefully.

Open a shell, switch to being the root user by using the "su -" command,
type in the root user password, and hit enter.  You'll need to be root
to use grub.

Type in the "grub" command, and hit enter.  Now you're in the grub
shell, instead of the bash shell.  The commands you type, from now on,
are grub commands.

Type in the "md5crypt" command, and hit enter.  Now you type in the
password that you want to use, and hit enter.  It'll spit back a string
of characters that is the encrypted version of your password.  It's this
string of characters you'll put into your grub.conf file.  Don't use the
string of characters that the web page shows as an example.

In your grub.conf file, before the first title sections, you'll put in
the password next to the "password --md5" instruction, like I've done
below.  The "--md5" bit of the command line details the type of
encryption that was used with the password.



 password --md5 $1vcvbhnjmk,l;;lbvcdC.

 title Fedora

Now, with that in place, only someone who knows the password can press
the "e" key in the grub boot screen to temporarily change how the
computer will boot.  All they can do is pick from the choices in the
menu.  If they attempt to use the "e" (edit) function, they'll be asked
to type in the password.

On top of that, if you wish to lock out some of the menu choices, so
that only someone with the password can use them, then simply put the
"lock" instruction directly under the title line.  Like this:

 title Boot from floppy disk drive
   rootnoverify (fd0)
   chainloader +1

And then.... if you want different passwords for different menu items,
put the password line within the different title sections of the
grub.conf file, instead of having one password line above all of them.

title WinXP
   password --md5 $1iuyfd56tghjhgC.
   rootnoverify (hd0,0)
   chainloader +1

 title Boot from floppy disk drive
   password --md5 $1vcvbhnjmk,l;;lbvcdC.
   rootnoverify (fd0)
   chainloader +1

If you're going to lock up the booting choices to stop people fiddling
with your PC, then you'll also want to change the BIOS settings, so that
someone can't simply boot from a CD or floppy, and bypass your grub.

Go into your BIOS, change the boot options so that your hard drive is
the only device that can be booted from, set a password on the BIOS,
save the settings and exit.

Now someone who wants to mess with your computer will have to open up
the case and yank out the drive or the BIOS clock battery, or reset the
BIOS.  That's going to be difficult to do without someone seeing them do

[tim at localhost ~]$ uname -r

Don't send private replies to my address, the mailbox is ignored.  I
read messages from the public lists.



Key fingerprint = 37B8 0DA5 9B2A 8554 FB2B 4145 5DC1 15DD A3EF E857

The life of a repo man is always intense.
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