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I was under the impression the Linux (in my case the Fedora OS) is very secure. However I've learnt with deep concern that that one can have access to the system during system startup i.e one can give various startup directives and bypass the normal login UI to have direct root access.
Is there a way to disble this so that the directives during startup are fixed and cannot be altered. I would like to make the system secure to the maximum extent possible.
Any suggestions on this will be very helpful.
1 -- use password protection in your bootloader (lilo, grub, etc..). This prevents people from changing the boot command line (partition can still be accessed using live media - see #2).
2 -- consider an encrypted install if you're worried about physical machine security. This would be most all-around secure, and will also prevent someone from booting the machine into "init=/bin/bash" maintenance mode, or accessing it using live media..
You should first protect your system with BIOS password(though,even that can be altered by removing BIOS battery)
Then password protect the GRUB so that no one can login by going in to Single User Mode.
GRUB Password protect link: http://forums.fedoraforum.org/showthread.php?t=216700
And to prevent by-pass using Rescue Mode you need to have disable boot from CD/DVD and USB and password protect BIOS.
Last edited by prayag_pjs; 11-16-2010 at 06:45 AM.
To secure a linux installation, or any server/desktop, you can start by:
1) Restrict access to the computer via Locked doors, cabinets, access cards and such. Cameras are nice too.
2) Lock the case (because someone can remove the cmos battery to reset the bios password)
3) Put a password on the BIOS
4) For more security restrictive areas, remove the CDROM and any USB ports (Ive had to unsolder them from motherboards for high secure areas)
5) For less security restrictive areas, disabling the CDROM and USB in the BIOS will be sufficient.
6) Install an OS that supports complete OFE (on the fly encryption) and encrypt all drives.
7) Install GRUB with a password
8) Set screensaver to logout the user after a specified period of time 2 min or something.
9) Disable any unneeded tty sessions
10) Disable the ctrl-alt-backspace shortcut to disallow someone from quitting X
11) Never log in as root into a graphical shell