Swap Space in Linux / RHEL / CENTOS / Fedora

What is a Swap space?

• Swap space is harddisk space that extends system RAM.

Swap space or virtual memory is hard disk space that acts as an extension of system RAM. Of course, due to the relative differential in data access on RAM versus hard disk, we prefer not to use swap space if it can be avoided. Nonetheless, it is vital to the proper functioning of a typical Linux system that some swap space  be made available.

Password protect GRUB / Lock Single User Mode In Linux / RHEL / CENTOS

The primary reasons for password protecting a Linux boot loader are as follows:

1. Preventing Access to Single User Mode — If attackers can boot the system into single user mode, they are logged in automatically as root without being prompted for the root password.

Rescue Linux Installation in RHEL / CENTOS / Fedora

Rescuing a Linux system is an easier task. There are several aspects of rescuing a Linux system.
 
Here we are going to see how to rescue an installed Linux system when the GRUB is deleted.

Enter Single user mode in Linux / RHEL / CENTOS / Fedora

If you are using GRUB bootloader

• Select the particular kernel to boot in (use up and down arrows in the GRUB splash screen)
• Now you will find an option "press a to append..". So press the key "a".
• Now press the space key to add at the bottom of that line.
• Append the word the "s" or "single" to the end of the kernel line.
• Press Enter

Change / Hack the Root password in Linux / RHEL / CENTOS / Fedora

Forgot root password

Suppose you want to get into a Linux system. You know nothing about the existing user's or their passwords. You have no idea about these things. Then what will you do??
The only thing you know that the user root exists. So we must find a way to get the root's password.