Firewall Rules

How Firewall Rules Works?

• As we have seen, the firewall rules are for traffic filtration. While we are adding any firewall rules, the rules entry will be made in the firewall config. When any network traffic comes, then the files will check the set of rules available. As per the rules, the firewall will take the decision. The decision has three options like accept, drop, or reject. Every action has its own meaning. The same keyword will help the firewall to take the necessary action on the same. In other words, the accept, drop or reject is acts as an action for the firewall. As per the necessary action, the firewall will take the necessary action. If accepted, the firewall will allow the network traffic to flow on the specific URL or the port. If it is a reject action, then the firewall will block the network traffic to flow on the specific URL or the port and provide the error message like “unreachable” error. If it is a drop action, then the firewall will drop the network traffic to flow on the specific URL or the port without any error message.
• In the firewall rules, it depends on the incoming and outgoing traffic. In the normal server and client communication, there is incoming and outgoing traffic. The incoming traffic will help to understand the network tariff or the network packet is coming from the external world. The traffic is having basic information like the port no, URL address, data information, etc. In the incoming firewall rule, we need to identify that the data or the network traffic comes from the external world. Which is correct or not. If it is correct, then only the firewall will allow passing the traffic to the system. Similarly, there is outgoing traffic. Normally in the outbound rule, we are open for all the network traffic. It will depend on the requirement that we need to define the outbound rule or not.

Examples of Firewall Rules

Given below are the examples of Firewall Rules:

Example #1

Firewall Rules: At the Windows Platform.

As we have seen, there are different firewall devices (from different vendors) available. Therefore, we need to follow different processes and methods in terms of the firewall rule. Similarly, we can manage the firewall rules in terms of the hardware or the software level also. Here, we are working on the windows operating system firewall rules.

Code:

It is not a specific syntax; we just need to follow the access flow.

Windows key -> search for control panel -> windows firewall -> Advance setting -> Click for the new rules.

Explanation:

• As per the above flow, we are able to add the new firewall rule in the Windows environment. In the windows environment, it is a bit easy to do that. But we need an administrator or full access to the respective operating system.

Output:

Example #2

Firewall Rules: At the Linux Platform.

In every operating system, the firewall service is running on. We can also manage the firewall rules also. For example, it will help to allow or disable the network traffic in the system.

Code:

firewall-cmd --zone=public --permanent --add-port=25/tcp --add-port=549/tcp
firewall-cmd –reload
firewall-cmd --info-zone public

Explanation:

• As per the above command, we are using the 3 commands. As per the below screenshot, we are getting the default firewall zone information. We are doing changes in the firewall rules and adding the new rule with the ports 25 and 549 ports.

Output:

Conclusion

We have seen the uncut concept of the “firewall rules” with the proper example, explanation and command with different outputs. It helps to filter the inbound network traffic as well as the outbound network traffic. The firewall is working on the TCP layer at level 7.

Recommended Articles

This is a guide to Firewall Rules. Here we discuss the introduction, how firewall rules works? And examples, respectively. You may also have a look at the following articles to learn more –

1. Firewall Devices
2. Firewall Uses
3. Types of Firewalls
4. What is a Firewall?