LINUX HACKING,

Hacking linux systems :

Linux systems can be hacked in the following manner. Consider a linux based system which is secured by a user password which you are not aware of.  Even though we do not know the password of the system we can still enter the system. The trick behind this is to change the password of the system to a new password without knowing the old password.

But before you proceed to do that I think that it would be helpful to understand how the linux based security works:

   GRUB – grand unified boot loader :

“GRUB is the reference implementation of the multi boot specification, which enables a user to have multiple operating systems to have on a system and choose which one to run when the pc starts. Grub can be used to select from different kernel images available on a particular partition.” It starts the UNIX kernel  

Run levels in linux –

There are 7 run levels in linux

Run level 0- halt / switch off

Run level 1-single user  mode without networking

Run level 2-with networking

Run level 3-console mode

Run level 4-not used

Run level 5- gui mode with networking

Run level 6 reboot

The following steps are for red hat linux

1>     Start the system and keep pressing down arrow key to stop booting on flash screen. The flash screen is the one where there the system asks u to select the os for booting (windows xp ,linux etc).

2>     Highlight the option of red hat linux

3>     Press ‘e’ – to edit the kernel and change the password

Three options will be displayed . out of the three, select the second option i.e.

/vmlinuz -2.6.18-8. El5 è kernel

4>Press ‘e’ to edit

5>Type 1 .press enter

Press  ‘b’ to boot the machine

4>     Now shell script will be displayed

5>     To change password type ‘passwd’ press enter

6>     Now it will ask to enter new password , so enter your new password

7>     To go in console mode with networking

Init 3. Press enter

Now ,  it will ask for user name and password  . So, now you can login through new password J