Hack root password and modify user mode under Linux

-----------------------experiment one: Break the root password----------------------------

1. Init 1

2, enter the diagram interface, and then enter the diagram two interface, enter single, S, S, 1, enter the one-user mode.

3, did not enter the command to enter the system, you can change the passwd, the crack success. Init 5, restart.

To prevent the method from being cracked:

First, vim/boot/grub/grub.conf

Add password under Hidden menu: passwd magedu (Clear, Low security)

Default selection Startup item title, added separately after kernel and INITRDH (hd0,0)

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After that, it's not that easy to hack a password into a single user.

After restarting, go to the menu page, press p, enter the correct password to enter.

Second, the plaintext password is not safe, set into ciphertext.

Grub-md5-crypt Special encryption file, input magedu, get ciphertext

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Copy Ciphertext to vim/boot/grub/grub.conf

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After restarting, go to the menu page, press p, enter the correct password to enter.

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(Figure-Start)

Third, if the ciphertext password is placed in the following location, it becomes the operating system startup password. Reboot to enter

(Figure-Start) interface, press Enter and a password is required to start.

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-------------------------Experiment Two: Modify user mode-------------------------

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1, vim/etc/inittab view Current user mode--id:5:initdefault:

2, Id:5:initdefault: modified to id:3:initdefault:--boot automatically enter 3 mode

If you change to 6, the boot cycle will occur;

The experiment is as follows: Change to 6 mode after reboot, after restart, press Ctrl+alt to enter diagram one interface and select

Centos 6 .... This item, then press A to enter the diagram two interface;

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(Figure I)

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(Figure II)

3, enter the number 5, temporarily into the 5 mode, skip the previously modified 6 mode.

4, restart after the user login, Vim/etc/inittab, change back to the original mode.

This article is from the Linux file system blog, so be sure to keep this source http://13250262.blog.51cto.com/13240262/1968193

Hack root password and modify user mode under Linux