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From root it is possible to set a single character password for any account


Here I created a account test3 and set the password t, and the password is accepted

[root@localhost ~]# useradd test3
[root@localhost ~]# passwd test3

Changing password for user test3.
New password: 
BAD PASSWORD: it is WAY too short
BAD PASSWORD: is a palindrome
Retype new password: 

passwd: all authentication tokens updated successfully.

But when it comes to regular user-mode it is very difficult change a password. Check this example

[avi@localhost ~]$ su - test3

[test3@localhost ~]$ passwd
Changing password for user test3.
Changing password for test3.
(current) UNIX password: 
New password: 
BAD PASSWORD: it is based on a dictionary word

passwd: Authentication token manipulation error

I logged into that account and tried to change the password, but this time it not taking simple password, I just knew that its because of pam (Pluggable authentication module ie: /etc/pam.d/)

What changes I do to set any password from regular user? Like being root if we give any password it will accept even single character also. I want that method in user-mode also

I know it's crazy but I want to learn that's it. I am using CentOS 6.2

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