Linux Password Trick

Here is a linux password trick using a extfs 2 file system. Login as root
Run the following command
# chattr +i /etc/shadow
above command will write protect the /etc/shadow file
Now try to change passwd using
#passwd
It will work!!!!
Now try to login using new password
It won't work!!!!!
Now try using old password
It works!!!!
This is beacuse of +i attribute to /etc/shadow file
Only the superuser or a process possessing the CAP_LINUX_IMMUTABLE capability can set or clear this attribute.
Get the list of Linux second extended file system using the lsatter command
# lsattr /etc/shadow
For changing the password you need to change attributes using
# chattr -i /etc/shadow
# lsattr /etc/shadow
Try this at your own risk!!!