What is a firewall and what are its types?

With the rise in cyber-attacks and security threats, the need for solutions to protect data and information for individuals and organizations is more critical than ever. One of the most vital solutions in this field is a tool called a firewall. Firewalls play a crucial role in monitoring incoming and outgoing network traffic. In this article, we will define firewalls, discuss their importance, explain how they work, and describe their various types.

What is a Firewall?

A firewall is software or hardware designed to prevent unauthorized access and security threats to internal networks and computer systems. It achieves this by using a set of rules to determine which traffic is allowed to enter or leave the network.

Why is Using a Firewall Important?

Here are some of the key reasons for using a firewall:

• Preventing Unauthorized Access: A firewall acts as a protective barrier that prevents unauthorized individuals from accessing networks and systems.
• Protecting Against Cyber Attacks: As mentioned, firewalls can monitor network traffic, detect suspicious and abnormal activities, and identify and block attacks such as DDoS attacks.
• Managing and Controlling Network Traffic: Firewalls allow network administrators to precisely manage and control network traffic, identifying and managing authorized and unauthorized traffic, ultimately improving network performance.
• Complying with Security Standards: Many organizations across various industries must adhere to specific requirements and standards. Using a firewall is one of these requirements, helping organizations achieve optimal security compliance.
• Improving Network Performance: Firewalls can block unnecessary traffic, reducing the load on the network and thus improving overall performance.

How Does a Firewall Work?

We explain the operation of a firewall in five stages below:

1. Defining Rules: At this stage, the network administrator sets a series of rules and policies based on the network's security needs. These rules include permissions and prohibitions based on criteria such as IP addresses, ports, protocols, and traffic types.
2. Analyzing Traffic by the Firewall: The firewall receives the network's incoming and outgoing traffic and first analyzes the data packet headers to examine the source and destination, the type of protocol, and the ports used.
3. Comparing with Rules and Policies: The firewall compares each data packet with the defined rules and policies, determining whether the traffic is authorized or unauthorized based on their compliance with the rules.
4. Taking Additional Actions: In more advanced firewalls, network traffic may undergo further filters, such as deep packet inspection or behavior analysis.
5. Allowing or Blocking Traffic: Data packets that comply with the rules and are deemed authorized are forwarded to their destination, while unauthorized packets are blocked, preventing their access to the network or system.

By understanding and implementing firewalls, organizations can significantly enhance their network security, manage traffic efficiently, and ensure compliance with security standards, ultimately leading to better overall performance and protection against various cyber threats.

What Types of Firewalls Exist?

Firewalls come in various types and can be categorized based on their implementation methods and functional characteristics. We will first explain the types of firewalls based on their implementation and placement.

Implementation and Placement-Based Types

1. Software Firewalls: These firewalls are installed as software on the operating systems of servers, personal computers, and other devices.

2. Hardware Firewalls: Hardware firewalls are physical devices typically placed at the entry and exit points of large networks. They filter incoming traffic to the internal network.

3. Cloud Firewalls: These firewalls are deployed as software services within cloud infrastructures.

4. Hybrid Firewalls: Hybrid firewalls are either physical devices with advanced software or software that simulates hardware capabilities.

Functionality and Application-Based Types

Firewalls can also be categorized based on their functional characteristics and applications. Each type has its own advantages and disadvantages, which we will briefly explain.

1. Packet-Filtering Firewalls

• These firewalls inspect data packets based on source and destination IP addresses, ports, and protocols. They make decisions on whether to allow or block traffic. These are the first generation of firewalls and operate at the network and transport layers.
• Advantages: High processing speed and low implementation cost.
• Disadvantages: Limited filtering capabilities for higher layers and inability to detect more complex attacks.

2. Proxy Firewalls

• These firewalls act as intermediaries between users and external resources. User requests are first sent to the proxy firewall, which then forwards them to the destination.
• Advantages: Deep inspection of traffic, providing higher security.
• Disadvantages: Potential reduction in speed and performance due to deeper inspection.

3. Stateful Inspection Firewalls

• These firewalls, in addition to inspecting packet headers (like packet-filtering firewalls), also maintain connection states. They can track and make more informed decisions based on the state of the connection.
• Advantages: Ability to identify and block unauthorized traffic hidden within legitimate packets, providing higher security than packet-filtering firewalls.
• Disadvantages: Higher cost and more complex implementation compared to packet-filtering firewalls.

4. Next-Generation Firewalls (NGFW)

• NGFWs incorporate advanced techniques such as deep packet inspection, intrusion detection and prevention systems (IDS/IPS), and traffic behavior analysis.
• Advantages: Offer advanced features and capabilities, providing very high security.

Importance of Monitoring Firewalls

Just as network monitoring is crucial, monitoring firewalls is equally important as they are a vital part of network security. Continuous monitoring of firewalls and analyzing performance indicators ensure that firewalls are functioning correctly and maintaining network security.

Firewall Monitoring on the Moien Platform

Currently, the Moien monitoring platform communicates with firewalls and security devices from brands like Fortinet, Sophos, F5, and Cisco using the SNMP protocol, monitoring various performance indicators. You can click on each brand name to see the specific indicators that can be monitored.