How to Break Linux password ... !

Dear friends!

Did you know that default Linux installation is vulnerable?

Linux root password can be broke easily by modifying ‘/etc/shadow’ file.

In Linux/Unix ‘shadow’ file used to store user name, password, account validity period etc.

User password is stored into 3^rd column in encrypted form and each column is delimitated by :, e.g.

Root:x:/qwYnM6ulk … :9999:7:1:::

You can not change the shadow file from running Linux.

Only you need to boot up the target system with a live Linux cd ( may be Knopix, backtrack ) and log into the system as root user.

If you empty the 3^rd field it implies that no password is set against root account. After modifying the field will look like this,

Root:x::9999:7:1:::

Save the file and reboot your system.

Try to log into system as root, you will no need of password at all.

I tried it in different version of Linux (Red Hat 9, Fedora 7, Mandrake 10.0) it worked successful. But in harden Linux system it may not work.

Note: You must take a back up copy of ‘/etc/shadow’ file for emergency shadow file recovery.

Change TTL value for Linux ...

You can change your Default TTL value of LINUX by editing the /etc/sysctl.conf file and add the line ,

net.ipv4.ip_default_ttl = <0-255>

&

Reboot your system ...