The way the Firewall works is quite simple. We know that things do seem complex from the surface but through this tutorial, we are going to explain the basis of IPTable and the use of basic commands so that even if you are a networking student or want to deep dive into networks, you can benefit from this guide.

The –dport number is the same as in /etc/ssh/sshd_confi # iptables -A INPUT -p tcp -m state -state NEW -dport 22 -j ACCEPTĪdd a new rule to drop the traffic for the correspondent ip address ( ip) # iptables -A INPUT -s 66. you are using Computers for while, you must be familiar with the word “ Firewall”. # iptables -A INPUT -p tcp -dport 443 -j ACCEPTĪllowing SSH connections. # iptables -A INPUT -s 192.168.100.0/24 -j ACCEPTĪllowing the internet traffic # iptables -A INPUT -m state -state ESTABLISHED,RELATED -j ACCEPTĪllowing all outbound traffic # iptables -A OUTPUT -j ACCEPTĪllowing HTTP and HTTPS connections from anywhere (the normal ports for websites # iptables -A INPUT -p tcp -dport 80 -j ACCEPT

Allowing the packets from your LAN (first, you must know the local IP address using the ‘ifconfig’ command). If you want to change the policies you can do it with the following command: iptables -P CHAIN POLITICS Delete the rules of iptables # iptables -Fįor example: if the default policies of INPUT are DROP, the firewall denies all the internet traffic. This allows anyone accesses to anything from anywhere. The iptables rules manage the packets of a specific protocol, for example, if you want to deny an internet connection iptables can do it. Port: a numerical designation representing a particular protocol Iptables rules: Protocol: a language and set of rules that network devices operate by First Concepts: Packet: a logical container representing the flow of data Fortunately, there are many configuration tools available to assist: e.g., fwbuilder, bastille, and ufw. A firewall is a network security system that monitors and controls incoming and outgoing network traffic based on predetermined security rules.Ĭonfiguring iptables manually is challenging for the uninitiated. Iptables is a great firewall included in the netfilter framework of Linux.

Ubuntu iptables