The reason for the shadow file is /etc/passwd is world readable and
needs to be, however if someone can gain access to the actual hashed
passwords that at one time were contained in the passwd file you can do
a brute force attack and gain access to different accounts on the
machine. By moving the actual hassed passwords out of the passwd file
into the root only readable shadow file it is much harder for someone to
capture the actual password hashes and without those it is MUCH harder
to attempt a brute force attack on a machine.

On Thu, 2002-02-21 at 15:10, JM wrote:
> What is the purpose for the file /etc/shadow-
> or for the files
> /etc/passwd-
> /etc/gshadow-
> /etc/group-
> 
> These files are nearly identical to their
> cognates in content and file attributes.
> Is there a simple explanation for maintaining
> these files along with the standard file:
> 
> /etc/shadow, /etc/passwd, /etc/gshadow, /etc/group ?
> 
> Is the a common convention for other Unix-like systems?
> 
> My reason for asking is that this is a minor inconvenience
> when hiding this /etc/shadow- file and what programs may
> be using this file.
> 
> Jerry M.
> a RedHat user
> 
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