An Overview of Firewalls

According to a study conducted at the Clark School of University of Maryland, hackers attempt to gain access to a computer with Internet access approximately every 39 seconds. The staggering number of hacking attempts that occur each day should encourage individuals and businesses alike to put security measures in place that help to prevent hacking attempts from becoming successful. Here, the digital security experts at Atlantic Data Forensics provide information on one of the most common digital security measures available: the firewall.

What is a Firewall?

A firewall is a tool that helps protect your computer by shielding it from malicious or unnecessary network traffic and preventing malicious software from accessing your network. A firewall is to your computer as a bouncer is to a bar, allowing wanted guests in while ensuring unwanted individuals stay out.

Firewalls exist in both software and hardware forms. A hardware firewall is also known as a network firewall, and it is an external device that is placed between your computer and Internet connection. Hardware-based firewalls can be useful to protect a collection of computers, making them particularly valuable for businesses with several or more devices. Software-based firewalls are downloaded to your computer in order to provide protection. Software-based firewalls can be useful in order to control the specific network behavior of individual applications on a system, however, a software-based firewall alone may not be enough protection.

How Do Firewalls Protect Computers?

Firewalls protect computers in a variety of ways. The main five types of firewalls are described below:

Packet Filtering

The original form of firewall, packet filtering firewalls inspect the headers of packets of data sent to your computer. If the packet header does not meet a set of predetermined rules, it will not allow the packet through the filter. Once a set of rules has been established, packet filtering firewalls can function in three different ways: they can either reject, or “drop,” all packets that do not meet the predetermined rule set, drop only the packets it is certain are unsafe or simply quarantine packets that may be unsafe and allow the user to decide whether it should be dropped or accepted.

Stateful Filtering

Stateful filtering firewalls also use packet filtering, but additionally inspect the connection state of a device via the application layer of the packet. This type of firewall takes packet filtering a step further and provides a more secure filtering system. These types of firewalls may be vulnerable to IP spoofing attacks, where an attacker impersonates a benign machine by manipulating IP packets.  

Application Layer Firewalls

An application firewall is a form of firewall that controls input, output and access to or from your computer by an application or service. This type of firewall operates by monitoring and potentially blocking the input, output or system service calls that do not meet the predetermined policy of the firewall—in this instance, entire packets of data are inspected.

Circuit Level Gateway

A circuit level gateway is a type of firewall that provides User Datagram Protocol (UDP) and Transmission Control Protocol (TCP) connection security. It functions by monitoring the TCP “handshaking” to determine if a session is requesting legitimate access and acts as a circuit for proxy servers and internal clients.

Stateful Multilayer Inspection

The most robust of firewalls, stateful multilayer inspection combines packet filtering, application layer firewalls and circuit level gateways into one firewall. Consequently, these firewalls are complex, and a business must ensure they have a team with a deep knowledge of these firewalls before employing them for their network.

What Happens if a Firewall is Configured Incorrectly?

In order to be effective, firewalls must be configured in such a way that they accurately block unwanted traffic. Most commercial firewalls come pre-configured and are ready for use; however, your firewall vendor, ISP or a digital security specialist may be able to provide additional assistance if specific configurations are required.  

It is important to remember that employing a firewall does not mean your system is invulnerable to attacks. Firewalls, while useful against malicious traffic, are less effective against malicious programs (malware) and may not prevent other forms of attacks. Be sure to incorporate firewalls as one of several security features employed by your system, instead of relying on it as your only source of network protection.

If the worst happens, and your network is compromised by a malicious entity, you need a team of experts who can quickly and discreetly stop the bleeding and ensure your system is safe once again. The cybersecurity and digital forensics experts at Atlantic Data Forensics have years of experience helping individuals and businesses, both large and small, manage data security crises. Talk to one of our experts today.

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