First of all disconnect your PC from the internet connection !
Steps to recover lost root password:
(Here I'm assuming that you are lot allowed to boot into linux maching through single user mode or your Bootloader is password protected. )
Step 1: For Redhat and Mandrake:
Then boot from your first install CD and as the very first screen comes up hit F2 and type:
rescue ( For RedHat "linux rescue" )
and the computer will boot in rescue mode.
It will show a few alternatives, select : ¨mount the existing partitions¨ and go to the shell/console prompt.
( Booting Mandrake in "failsafe" from the Lilo menu does the same )
Step 1: For SUSE:
Boot from your first install CD and press F1 at the first screen, then choose "Rescue System" from the menu and at the prompt type "root" ( you do not need a password )
Step 1: For other distro's
Boot from the first install CD ( or any Live CD like Knoppix ) and at the bootprompt type:
CODE
linux single
( For Knoppix: knoppix single )
And it will boot in "single user mode" and you will get an odd looking prompt like “sh-2.05b#”
Alternative for step 1
Sure with most Live and Rescue CDs you can also just boot in the live version, mount the partition and, as root, make changes to the files indicated below:
Step 2
CODE
# cd /etc
( if you boot from knoppix first cd to the partition your lost-password-distro is on )
We need to change two files; ¨passwd¨ and ¨shadow¨:
CODE
# vi passwd
( opens the file )
< i > ( puts vi in insertmode )
This is the first line:
root:x:0:0:root:/root:/bin/bash
Make it:
root::0:0:root:/root:/bin/bash
So just get writ of the ¨x¨ do not touch the ¨:¨ ( colons )
Save the file:
Esc
ZZ
Second file to be changed:
CODE
# vi shadow
( open the file )
< i > ( insert mode )
The first line is a long scrambled line of characters, just make it:
root:::: ( four colons ! )
Save the file and quit editor.
wq
Now you can reboot your computer. Log in as normal user, open a console and type:
CODE
$ su
# passwd
And set the new root password !
Log out as root:
Ctrl+d
And the job is done !!
WARNING: Only after setting your new root password it is safe to connect your computer to the internet or local network again !!