Firewall Level and Types: Explained


What Is a Firewall?

In computing, a firewall is a special type of network security system that monitors and controls incoming and outgoing network traffic based on security rules. A firewall typically establishes a barrier between a trusted internal network and untrusted external network, such as the Internet.


Firewalls are often categorized as either network firewalls or host-based firewall. Network firewalls filter traffic between two or more networks and run on network hardware. Host-based firewalls run on host computers and control network traffic in and out of those machines.

The primary purpose of a firewall is to allow secure traffic and prevent malicious traffic for protecting the computer from viruses and attacks.

Firewalls may also be a component of your computer's operating system. For example, Windows Firewall is a Microsoft Windows application that notifies users of any suspicious activity. The Application can detect and block viruses, worms, and hackers from harmful activity.

Firewalls Types

Firewalls are network security systems designed to monitor and control incoming and outgoing network traffic based on predetermined security rules. There are several types of firewalls, each with its own characteristics and purposes:

Packet Filter:

Looks at each packet entering or leaving the network and accepts or rejects it based on user-defined rules. Packet filtering is fairly effective and transparent to users, but it is difficult to configure. In addition, it is susceptible to IP spoofing.

Stateful Inspection Firewalls:

Combine packet filtering with an awareness of the state of active connections and, Keep track of the state of active connections and make decisions based on the context of the traffic (e.g., whether a connection is part of an established session). Also, offers better security than packet filtering alone, as it considers the state of the connection.

Application Gateway:

Applies security mechanisms to specific applications, such as FTP and Telnet servers. This is very effective, but can impose a performance degradation. Also, it provides more granular control over the types of traffic allowed or denied.

Proxy Server:

It intercepts all messages entering and leaving the network. The proxy server effectively hides the true network addresses. Instead of allowing direct connections between networks, proxy firewalls forward requests on behalf of clients, making it more difficult for attackers to directly access internal systems.

Circuit-level Gateway:

It applies security mechanisms when a connection is established. Once the connection has been made, packets can flow between the hosts without further checking. Monitor TCP handshakes to determine whether a requested session is legitimate. Once a connection is established, the firewall allows data to flow directly between the hosts.

Next Generation Firewall:

Work by filtering network and Internet traffic based upon the applications or traffic types using specific ports. Next Generation Firewalls (NGFWs) blend the features of a standard firewall with quality of service (QoS) functionalities in order to provide smarter and deeper inspection.

Unified Threat Management:

Unified Threat Management (UTM) firewalls consolidate various security features, including firewalling, intrusion detection and prevention, antivirus, content filtering, and VPN capabilities, into a single integrated appliance. UTM firewalls offer simplified management and are suitable for small to medium-sized businesses seeking comprehensive security solutions.

Cloud Firewalls:

With the rise of cloud computing, cloud firewalls are specifically designed to protect cloud-based infrastructure and applications. These firewalls operate within cloud environments and provide security controls for virtual networks, instances, and services hosted in the cloud.

Note: Each type has its strengths and weaknesses, and the choice of firewall depends on the specific security requirements and the network architecture.

Category: Security

on: 20 Dec 2018

on: 03 Jul 2023

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