Tips To Protect Linux Servers Physical Console Access

Posted on in Categories Debian Linux, Hardware, Howto, Kde, Linux, Linux desktop, Linux distribution, package management, RedHat/Fedora Linux, Sys admin, Tips, Ubuntu Linux last updated March 12, 2009

This is an user contributed article.

Linux computer console is a physical device to operate a computer / server. Here are few steps which, if taken, make it more difficult for an attacker to quickly modify a system from its console.

How to: OpenBSD reset root password

Posted on in Categories OpenBSD, Sys admin, Tips last updated September 19, 2007

If you forgot your root password, you can simply reset it. The general procedure for resetting password is as follows (if you are a Linux user, see how to reset Linux root password):

a) At boot> prompt force openbsd to boot into a single user mode

b) Next mount file system in read-write mode

c) Run passwd command

d) Sync file system

e) Reboot and login normally.

Procedure to reset root password

At boot> prompt type boot -s to boot into single user mode:
boot> boot -s
Next you will see a message as follows:

Enter pathname of shell or RETURN for sh:

Just hit [Enter] key to load sh shell.
Next mount / and /usr file system in read-write mode:
# mount -uw /
# mount /usr

Finally set or change the password for root user, enter:
# passwd
Press CTRL+D to boot into multiuser mode or just reboot server:
# reboot

Further reading

HowTo: Recovering Linux Grub Boot Loader Password

Posted on in Categories CentOS, Debian Linux, Howto, Linux, RedHat/Fedora Linux, Suse Linux, Sys admin, Tips, Troubleshooting, Ubuntu Linux last updated February 20, 2006

If you have, a password protected grub boot loader and you forgot both root and grub password, then you can recover grub-boot loader password using the following method/procedure:

* Use Knoppix cd
* Remove the password from Grub configuration file
* Reboot the system
* Change the root password
* Setup new Grub password if required (optional)

Linux: Recovering Deleted /etc/shadow Password File

Posted on in Categories Data recovery, Howto, Linux, Sys admin, Tips, Troubleshooting last updated December 21, 2005

You may delete a file called /etc/shadow. If you try to boot into a single user mode, system will ask for the maintenance root password. Now imagine this, you do not have a backup of /etc/shadow file. How do you fix such problem in a production environment where time is a critical factor? I will explain how to recover a deleted /etc/shadow file in five easy steps.

How Do I Secure Grub Boot Loader?

Posted on in Categories Debian Linux, Howto, Linux, Linux desktop, RedHat/Fedora Linux, Security, Sys admin, Tips, Ubuntu Linux last updated October 19, 2005

You can set a password for the GRUB bootloader. This prevents users from entering single user mode or changing settings at boot time.

When your system is rebooted, grub presents the boot option menu. From this menu one can easily login into a single user mode without the password which might result into compromise system security.

For example, anyone can access the data or change the settings. However you can setup a password for grub with password option. This option forces grub to ask for a password before making any changes or entering into single user mode. You need to type p followed by password.