Disable SELinux on Ubuntu:

Introduction:

• Also known as Security Enhanced Linux.
• SELinux is a MAC (mandatory access control)module present in the kernel of Linux systems. It is developed by Redhat and NSA and released around 1998.
• It is an additional layer of security services on top of the standard Linux DAC (Discretionary access control) User/Group based permissions.
• It adds protection to your Linux operating system by not allowing everything that has not been specifically allowed.
• It is an open-source application that protects the host by isolating each application and confining its activities.
• By default, Ubuntu uses AppArmor and not SELinux,

Disable SELinux on Ubuntu:

• By default, it is installed in Ubuntu and you can validate by running the following command:

sestatus
SELinux status:                 enabled
SELinuxfs mount:                /sys/fs/selinux
SELinux root directory:         /etc/selinux
Loaded policy name:             targeted
Current mode:                   enforcing
Mode from config file:          enforcing
Policy MLS status:              enabled
Policy deny_unknown status:     allowed
Max kernel policy version:      28

As we can see SELinux is enabled.

Disable SELinux Temporarily:

• The following methods only works until the system does not reboot.
• It will update for the current shell.

# echo 0 > /selinux/enforce
        or 
# setenforce 0

        or 
# setenforce Permissive

Disable SELinux Permanently:

To permanently disable SELinux, use any text editor to open the file /etc/sysconfig/selinux as follows and set:

SELINUX=disabled

• Update and close the file, and don’t forget reboot then only it will start working.
• After Reboot.
• Validate, it should look like below.

$ sestatus
SELinux status:                 disabled
SELinuxfs mount:                /sys/fs/selinux
SELinux root directory:         /etc/selinux
Loaded policy name:             targeted
Current mode:                   enforcing
Mode from config file:          enforcing
Policy MLS status:              enabled
Policy deny_unknown status:     allowed
Max kernel policy version:      28

Thanks

Happy Learning!!