What is a Host-Based Firewall?

Traditionally, firewalls are appliances that protect networks from malicious traffic. However, they can also run as a service on a computer by blocking harmful traffic from the device itself. This setup is called a host-based firewall, as they are hosted on a workstation, server, or network-connected device. Most modern operating systems already come with built-in firewall capabilities. They offer granular controls to protect individual hosts against unwanted traffic, so they’re quite popular among businesses. Let’s take a deeper look at host-based firewalls.

What is a Host-Based Firewall?

A host-based firewall is software that works on a singular device in a network, providing a protection layer by examining incoming and outgoing traffic. It effectively filters harmful content, ensuring malware, viruses, and other malicious activities do not infiltrate the system. In environments where network security is paramount, host-based firewalls complement perimeter-based solutions. While perimeter defenses secure the broader network’s boundaries, host-based firewalls bolster security at the device level.

How does it work?

Organizations often adopt host-based firewalls for device-specific security control. These firewalls include six inherent functionalities encompassing direct-to-device installation, rule-based decision-making, traffic monitoring, logging and reporting, rule set updates, and security suites integration.

Here’s what each function entails:

• Installation design: Host-based firewalls are installed directly on individual devices such as computers, servers, routers, and switches. If it’s properly set up, it becomes an integral part of the device’s security infrastructure by monitoring and controlling traffic.
• Decision-making: Firewalls make autonomous decisions on whether to accept or prohibit each packet based on the created rules. This occurs quickly to provide minimal latency and is fundamental to a firewall’s role in filtering and controlling data traffic.
• Traffic monitoring: Firewalls continuously analyze the device’s incoming and outgoing network traffic, comparing data packets to established rules. Then, they filter potentially malicious or illegal network activities.
• Logging and reporting: Host-based firewalls keep track of authorized and rejected traffic, which helps with troubleshooting and security analysis. This capability assists post-event analysis, troubleshooting, and keeping an audit record of network activity.
• Automatic updates: Firewalls frequently receive automatic rule-set updates to monitor emerging threats and provide protection against the most recent vulnerabilities.
• Integration with security suites: Host-based firewalls can be used with antivirus and other security technologies to provide layered protection against cyber attacks.

Host-based firewalls’ efficiency relies on proper setup and configuration across endpoints. They’re applied in certain use cases and have different advantages and disadvantages. To improve its effectiveness, determine the most appropriate firewall type and solutions for your organization’s demands.

Benefits of using a host-based firewall

Host-based firewalls offer protection against viruses and malware. However, this isn’t the only benefit that this type of firewall brings to its users.

Layered protection model

Having a host-based firewall and a network-based firewall creates two separate filtering mechanisms. While a network-based firewall examines data packet headers and block addresses or ports, host-based firewall functions act as an independent safeguard. Several layers of protection help to secure endpoints against a diverse range of threats.

Easy setup

It is much easier to configure than network firewalls. The fact that frequently they’re already built-in into the device’s operating system means almost no deployment is needed. The setup involves just adding required configurations to a system already in place.

Security against various threats

Host-based firewalls can protect against threats originating from within the internal network. Additionally, only host-based firewalls can block network connections associated with specific programs and prevent malicious scripts from email attachments. This can be an invaluable tool for stopping worms — self-multiplying malware. Such firewall software can block outbound connection ports for associated applications like Excel, Word, Notepad, etc.

Portability

It helps ensure continuous protection even when a device changes the network. The rules are applied per device, which means they are independent of the network. It allows a stable basis for security policies with mobile devices and laptops without interfering with the company’s network firewall.

Additional internal network controls

The main idea is that intra-subnet traffic is extremely difficult to control without host-based firewalls. This gives network administrators additional leverage when denying workstation communications. It could also backfire in a data breach, so limiting excessive interconnectivity is better.

Disadvantages of host-based firewalls

Host-based firewalls are good for a variety of use cases, but they can’t do everything. Here are a few of their shortcomings:

• Complexity: Managing individual firewalls on each host can be time-consuming and complex.
• Resource consumption: Running a firewall on each host can consume system resources, potentially affecting performance.
• Limited scope: Host-based firewalls only protect the host they are installed on, leaving other devices in the network potentially vulnerable.

When you should use a Host-Based Firewall

Host-based firewalls aren’t a stand-alone solution. You should only consider adding them to your family of network security tools once you have a more holistic solution applied.

While options such as network-based firewalls and Endpoint Detection and Response (EDR) can be used to elevate the security of your network, those tend to be more extreme approaches and are not always suitable for smaller organizations and businesses.

You should consider using a host-based firewall if you have a handful of devices, servers, or applications that carry particularly sensitive data and information. They can act as an added line of defense which you can enforce with strict rules and configurations that might otherwise be too restrictive for your network as a whole.

Furthermore, it can be used as an emergency solution to protect your most vulnerable assets until a more comprehensive security solution is installed.

Conclusion

When it comes to network security, the best firewall approach is layered, where host-based firewalls on individual machines and devices are used within a larger security framework that includes network-based firewalls. This ensures malicious data that slips past the outer perimeter firewall can still be blocked at the device level.

Host-based firewalls are a must for remote workers who frequently log in to disparate networks, whether at home or in public, where bad actors routinely attack unprotected networked devices. Not only is the individual device at risk, but employees could introduce malicious code to the network at large when they reconnect. This is also why employee education about firewall usage is critical.

Anytime firewalls are used, it’s important to establish best practices, especially around keeping configurations up to date. A firewall is only as effective as its latest update.