Tutorial Installation UFW Firewall for Linux

Tutorial Install UFW firewall for Linux

What is a firewall?
The firewall is a fortress of a job, where the fortress is made up of high walls and heavily guarded, and only has an entrance, so that whatever approaching / passing through the door to enter into, must go through the first inspection.
On the computer's operating system, this firewall is the same function as above, anyone who wants to get into the system must pass a door, and the firewall's task closes and opens the entrance. if there are users who want to enter, then there must be permission in advance of the firewall, if allowed then the door is opened.
in its scientific language Firewall is a system designed to prevent unauthorized access from outside or from within a computer network.
For example there are others trying to log in to the server by using brute force attack method that attacks port 23 telnet, this of course can threaten the security of server and existing network, hence with firewall, we can take by blocking port 23 so that user can not connect to server.
UFW (Uncomplicated Firewall) is an application released from IPtables and created with the aim of simplifying the firewall configuration process on Linux based operating system
Here's How to Install UFW in Kali Linux
Turn Linux Times up to normal position

Open Terminal and type
first you must update repository
#nano /etc/apt/sourcelist.txt

then, write this sourclist.
deb http://ftp.de.debian.org/debian sid main

# apt-get install ufw

After the installation is complete, we configure ufw in the appropriate way of image
# cd /etc/default/
# ls
show all file, must be found file ufw