Network Firewall

A network firewall is a critical security device or software that monitors and controls network traffic based on predetermined rules. It acts as a barrier between trusted internal networks and untrusted external networks, such as the internet.

Firewalls play a vital role in protecting computer networks by filtering traffic, controlling access, segmenting networks, and logging activities. They examine data packets entering or leaving the network, deciding whether to allow or block them based on set policies. This helps prevent unauthorized access, malware infections, and data breaches.

As a core component of network security, firewalls are the first line of defense against external threats. Their traffic-logging and monitoring capabilities provide valuable insights into potential security threats.

Additionally, firewalls offer a cost-effective way to enhance network security compared to the potential costs of a security breach. To give you an idea of how much that can save your organization, consider that the global average cost of a data breach in 2024 is $4.9 million.

Modern firewalls can be updated and configured to address new challenges posed by continuously evolving cyberthreats, making them adaptable and indispensable components of a comprehensive cybersecurity strategy.

• A network firewall is a cybersecurity tool that acts as a digital traffic barrier. It prevents unauthorized access by shielding an organization’s digital infrastructure from unsecured external networks, such as the internet.
• Maximizing your firewall’s effectiveness boils down to selecting the right firewall type, avoiding common misconfiguration mistakes, and finding the right product based on cost, scalability, and more.
• Properly selecting and implementing a network firewall provides businesses with benefits like enhanced security, traffic monitoring, and improved cyberthreat prevention.

A firewall’s role is to monitor, control, and protect network traffic. It acts as a protective barrier, preventing unauthorized access to private digital infrastructures via:

• Traffic filtering: This process involves examining data packets entering or leaving the network and deciding whether to allow or block them based on predefined security policies. Firewalls use various filtering techniques to achieve this:
• IP address filtering: The firewall checks the source and destination IP addresses of incoming and outgoing packets. It compares these addresses against a list of allowed or blocked IPs, determining whether to permit or deny the traffic.
• Packet filtering: This is a more advanced technique that examines the IP addresses and other information in the packet header, such as port numbers, protocols, and packet types. This provides more granular control over network traffic, enabling or blocking specific services or applications.
• Stateful inspection: This process tracks the state of network connections. It maintains a state table to remember the context of each communication session, enabling it to make more informed decisions about incoming packets based on their relationship to previous traffic.
• Application-layer filtering: Also known as deep packet inspection, application-layer filtering examines the actual content of the data packets rather than just their headers. This enables the firewall to identify and block specific applications or protocols, regardless of their port.
• Intrusion detection and prevention: Many modern firewalls also incorporate intrusion detection and prevention systems (IDS/IPS), which identify and respond to potential security threats in real time. They may also include features like virtual private network (VPN) support for secure remote access and network address translation (NAT) to hide internal network addresses from external view.

One of the first steps in maximizing your network firewall security’s effectiveness is ensuring a proper fit. Several different network configurations and firewall options are available.

Packet-filtering firewall

This is the most basic type of network security firewall that examines incoming and outgoing network traffic based on predefined parameters. It inspects packet headers, including source and destination IP addresses, port numbers, and protocols. Packet-filtering firewalls are fast and efficient but cannot understand the context of connections or inspect packet contents.

Stateful inspection firewall

An evolution of packet filtering, stateful inspection firewalls maintain awareness of the state of network connections. They track the state of sessions and make decisions based on predefined rules and the context of the traffic. This allows for more intelligent filtering decisions and better protection against certain types of attacks.

Proxy firewall

Also known as application-level gateways, proxy firewalls act as intermediaries between internal and external networks. They terminate incoming connections and establish new ones to the destination, effectively hiding the internal network. Proxy firewalls can perform deep packet inspection and provide content filtering, making them more secure but potentially slower than other types of firewalls.

Web application firewall (WAF)

WAFs are specifically designed to protect web applications from common web-based attacks. An example would be Amazon Web Services (AWS) firewalls. They inspect HTTP traffic and can detect and block threats like SQL injection, cross-site scripting (XSS), and other application-layer attacks. WAFs are crucial for protecting web-facing assets and ensuring compliance with data protection standards.

Unified threat management (UTM) firewall

UTM firewalls combine multiple security features into a single appliance. They typically include traditional firewall capabilities along with intrusion prevention, antivirus, content filtering, and sometimes even VPN functionality. UTM firewalls offer comprehensive protection but may sacrifice some performance for smaller- to medium-sized organizations, although modern platforms have become significantly more efficient.

Next-gen firewall (NGFW)

An NGFW is a cutting-edge firewall technology that incorporates features of traditional firewalls with advanced capabilities. It provides deep packet inspection, application-level filtering, and intrusion prevention, all within a platform that can integrate with threat intelligence feeds. NGFWs often include features like user identity management and SSL/TLS inspection.

Network firewalls offer a range of benefits that contribute to a robust cybersecurity strategy:

• Enhanced security: Firewalls separate trusted internal networks from untrusted external networks, preventing unauthorized access to sensitive data and systems by blocking potential threats. They allow only approved connections while restricting access to critical services, significantly reducing the risk of attacks.
• Traffic monitoring: Firewalls provide detailed network activity logs, offering visibility into potential security issues. This monitoring capability helps identify unusual patterns or suspicious behavior that may indicate an ongoing attack. Administrators can then quickly respond to anomalies, such as unexpected spikes in outbound traffic.
• Prevention of cyberattacks: Part of a firewall’s role within your network security is stopping common attack vectors before they can infiltrate the internal network. They block malware, deny access to known malicious IP addresses, and prevent unauthorized remote access attempts. They also thwart specific attacks, such as ransomware, by blocking communication with command and control servers.

Part of understanding firewalls and network security is knowing how to configure firewalls properly. Misconfigurations can significantly reduce their ability to protect against cyberattacks.

Review these common firewall misconfiguration scenarios and solutions to see which might apply to your own system.

Open policy configuration

Open policy configuration is a common misconfiguration where IT teams initially set up firewalls with overly permissive rules, allowing any traffic from any source to access any destination. This approach is often adopted for flexibility during setup but can be forgotten later, exposing networks to various potential threats.

Solution: To mitigate this risk, implement a “deny all” policy by default and only allow specific, necessary traffic. Regularly review and document all allowed traffic flows, ensuring each rule has a clear purpose and justification.

Overly permissive rules

Overly permissive rules occur when firewall configurations allow more traffic than necessary, creating security gaps and potential compliance issues. Administrators can create broad rules to quickly solve access problems without considering the long-term security implications.

This misconfiguration is similar to an open policy misconfiguration but is narrower in focus. Think of it like leaving a few specific doors unlocked in a house (overly permissive rules) vs. leaving all the doors and windows open (open policy configuration).

Solution: To avoid overly permissive rules, follow the principle of least privilege, which states that a user, program, or process should be granted only the minimum necessary access rights to perform its specific tasks. Create granular rules defining the source, destination, protocol, and port for each necessary traffic flow. Regularly review these rules to ensure they remain relevant and secure.

Default settings

Default settings are often left unchanged due to time constraints or lack of expertise, leaving firewalls with potentially unsuitable configurations for specific network environments. These settings may not align with an organization's security needs or industry best practices, creating vulnerabilities and expanding the attack surface.

Solution: To address this, always customize firewall settings according to your organization's specific requirements and security needs. Conduct a thorough review of default settings during initial setup and establish a regular schedule for reviewing and updating these settings as your network evolves.

Lack of monitoring and testing

While not necessarily a misconfiguration, a lack of monitoring and testing is a critical oversight that can mean failing to detect issues or vulnerabilities in firewall performance. Misconfigurations or emerging threats may go unnoticed without regular checks, potentially leading to security breaches.

Solution: To combat this, implement regular monitoring and testing schedules. Use appropriate tools to analyze firewall logs and performance metrics and conduct periodic penetration tests to identify potential weaknesses. Establish clear procedures for reviewing and acting upon the results of these monitoring and testing activities.

With a firm grasp on the types of firewalls available and common misconfigurations to avoid, it’s time to turn your attention to selecting the best network firewall for your organization. Consider the following factors when firewall shopping:

• Cost: Consider the initial purchase price of the hardware or software and ongoing expenses such as licensing fees, maintenance, and support costs. Additionally, factor in training expenses for IT staff to ensure they can effectively manage the firewall. It’s also beneficial to assess potential savings from consolidated security features, as a comprehensive firewall solution may reduce the need for multiple point products.
• Scalability: Scalability is essential for organizations anticipating growth. The firewall you choose should be capable of handling increased traffic volumes and supporting a growing number of users and devices. It should be easy to add new features or modules and be flexible enough to adapt to changing network architectures, including expansion to multiple sites or cloud environments.
• Ease of use: A firewall’s ease of use is critical for efficient management. Look for solutions with an intuitive user interface that simplifies configuration and management tasks. Centralized management consoles can facilitate the administration of multiple firewalls, while automated policy creation and optimization tools can reduce the risk of human error.
• Security features: A firewall's security features should align with the organization's specific needs. Key capabilities to consider include an intrusion prevention system, application awareness and control, and SSL/TLS inspection for encrypted traffic. Advanced threat protection features such as sandboxing and machine learning-based detection are increasingly important. Additionally, ensure the firewall supports VPN functionality for secure remote access and integrates well with user identity management systems.
• Performance: Performance is crucial to avoid bottlenecks in network traffic. Evaluate the firewall’s throughput capacity for various types of traffic, including HTTPS and VPN connections. Consider the latency introduced by security processing and the connection handling capacity. Hardware acceleration for specific security functions can significantly enhance performance.
• Integration: The firewall should seamlessly integrate with the existing network infrastructure. Compatibility is key, so assess whether the firewall supports common security information and event management (SIEM) tools and can integrate with cloud security services. Additionally, consider the availability of APIs for custom integrations and the firewall’s ability to work within software-defined networking (SDN) environments.
• Vendor support and reputation: Don’t overlook the level of vendor support and its reputation in the industry. Investigate the frequency and quality of firmware or software updates, as well as the responsiveness of customer support. The availability of professional services for complex deployments is also beneficial. Look to community resources, user forums, third-party reviews, and industry recognition to gauge the vendor’s reliability.
• Reporting and logging: Robust reporting and logging capabilities are vital for monitoring and compliance. Look for customizable reporting templates to provide insights tailored to your organization’s needs. Real-time monitoring dashboards enhance situational awareness, while log retention and searchability are crucial for audits. Finally, ensure the firewall can export logs for compliance purposes and integrate with external logging and analytics platforms for enhanced visibility.

The right network firewall is integral to your overall cybersecurity stack. Traffic filtering, logging, and reporting go a long way as a first line of defense, protecting your system from square one.

Of course, enlisting the help of the experts at Barracuda only makes the process easier. Schedule a CloudGen Firewall demo today, and our team will walk you through our comprehensive security solution for cloud and hybrid networks. Protect your data, users, and workloads with Barracuda CloudGen Firewall.