Firewall in Linux is heard weird when you read this post. Some of you will be laugh, and ask,”Bitch please, are you kidding me? Linux is safe, right?” Okay, you will do this because there are few crackers that attack Linux network (server, webhosting, etc). Usually Windows was targeted by crackers because Windows has a lot of users.
But Linux is a man-made system, it is not 100% safe from cracker attacks. Every software surely has bug, and many bugs can be exploited and became security issue. So the best prevention from cracker’s attack is by secure your system. One of the recommendation is by using firewall.
Recently I use UFW (Uncomplicated Firewall). UFW is Ubuntu-specific firewall. There are a GUI version called Gufw, so you can work with it easily. You can install Gufw by type on terminal
sudo apt-get install gufw
After install it, ufw is disable in default. You can check it by type
sudo ufw status
So you must enable ufw to make firewall works.
sudo ufw enable
If you want to disable it, you just type
sudo ufw disable
You can set deny or allow all incoming connections by default. Just type this
sudo ufw default deny
sudo ufw default allow
Simple. Now if you want to allow or block a specific address, you can use the following command
sudo ufw deny
sudo ufw allow
Check the following example
sudo ufw allow 22/tcp from $address/mask
sudo ufw deny 80 from x.x.x.x
You can see that 22 is TCP port, and 80 is HTTP port. For your information, HTTP used port 80, 8080, and 8008. It is readable, isn’t it? Okay, if you want to enable or disable logging in, just type this
sudo ufw logging on
sudo ufw logging off
Feel free to visit here to get more command about ufw
That’s all about firewall in Linux Ubuntu, you can use ufw (Uncomplicated firewall) or use others tool like iptables.