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Old 10-04-2006, 03:19 PM   #1
sunilmenamkulam
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User Name - Pass Word Mismatch


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I am having Redhat Linux on my system, but access is denied due to username-password mismatch. How can i change username and password both, so that i can have access to Linux?

SUNIL
 
Old 10-04-2006, 05:22 PM   #2
jantman
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Are you talking about the root user, or another user?

Have you checked the Caps Lock key?

If you forgot the root password, the only way to use the machine is to reinstall Linux.
 
Old 10-05-2006, 03:43 AM   #3
Wim Sturkenboom
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If I'm correctly informed (I'd never had to use it) reinstall is a bit overkill, just gain access to the machine (live cd, rescue mode of install cd) and wipe the password from /etc/passwd.
 
Old 10-05-2006, 10:18 AM   #4
jantman
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I don't know about the default of RedHat, but I have SuSE and it will specifically not allow that, for the obvious reason - then all you need to do to get past the root password is what you instructed.

If your machine will allow that, I would STRONGLY recommend changing it somehow.
 
Old 10-05-2006, 10:55 AM   #5
b0uncer
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Quote:
I don't know about the default of RedHat, but I have SuSE and it will specifically not allow that, for the obvious reason - then all you need to do to get past the root password is what you instructed.

If your machine will allow that, I would STRONGLY recommend changing it somehow.
Indeed. I think most distributions out there only let root access the file, but even then there is a problem: if bootloader is not protected, anyone can boot into single-user mode..with root privileges. This is a security flaw in unbelievably many systems, if the user doesn't secure the bootloader with a password. I recall Redora does ask for a bootloader password to be set during the setup, but many distributions do not.
 
Old 10-05-2006, 11:37 AM   #6
Lotharster
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Quote:
Originally Posted by jantman
I don't know about the default of RedHat, but I have SuSE and it will specifically not allow that, for the obvious reason - then all you need to do to get past the root password is what you instructed.

If your machine will allow that, I would STRONGLY recommend changing it somehow.
This is something no operating system can defend against. If the computer boots from a live CD, the normal operating system is not even started, so it cannot prevent this attack. Usually, the root partition is not encrypted, so anyone with direct access to the disk (with al live cd or by manually plugging the disk into another computer) can change the /etc/shadow file. The only defense is to prevent potential attackers from gaining physical access to the hard disk and disabling booting from removable media via BIOS (don't forget to password protect your bios also). However, most BIOSes have publicly known master passwords, and can be resetted with a switch on the main board.
 
  


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