Firewalls play a vital role in safeguarding your network and data against malicious actors. By acting as a protective barrier between your internal network and the outside world, firewalls provide an additional layer of security for web servers and data centers. However, to fully leverage the benefits of a firewall, it is crucial to follow best practices when configuring it. In this article, we will explore the optimal practices for firewalls and highlight common misconfigurations to avoid. By implementing these guidelines, you can ensure a more secure and resilient network for your organization.

1. Use the Latest Firmware and Patches

Firmware upgrades often contain fixes for known vulnerabilities that could potentially be exploited by cyber criminals. Ensuring that your firewall uses the latest firmware is a proactive step towards safeguarding your network against such threats.

Patch management, on the other hand, is an integral part of network security that often goes overlooked. Patches are essentially updates to the software running on your firewall that fix bugs, enhance functionality, and, most importantly, address security vulnerabilities. Regular patching can significantly reduce the risk of your network falling prey to attacks that exploit known software flaws.

To illustrate the impact of not following these practices, consider the scenario where attackers exploit a known vulnerability in outdated firewall firmware to gain unauthorized access to your network. Once inside, they could launch a range of attacks – from data theft to ransomware.

Alternatively, if patches are not regularly applied, a bug within the software could be manipulated to bypass firewall rules, potentially leading to a full-scale data breach. This not only puts sensitive information at risk but also incurs considerable financial and reputational damage. These scenarios underline the importance of maintaining up-to-date firmware and diligent patch management for your firewall.

2. Change All Default Passwords

When a firewall is first installed, it often comes with a default username and password set by the manufacturer. These default credentials are typically easy to find online, making them a ripe target for cybercriminals. If left unchanged, they create a significant security risk. Therefore, changing all default passwords is a crucial step in securing your firewall.

By changing the default passwords, you’re effectively locking the front door to your network. Hackers often rely on the negligence of network administrators who fail to replace default credentials. With unique, strong passwords in place, the likelihood of unauthorized access is dramatically reduced.

Moreover, it’s important to understand that a strong password is more than just a mix of letters, numbers, and symbols. It should be something that is not easily guessable by humans or computing algorithms. Avoid using common phrases, repeated characters, or personal information. A password manager can be an effective tool for generating and storing complex passwords.

3. Harden Your Firewall Using Industry Best Practices

By strengthening your firewall deployments, you can minimize the risk of unauthorized access to its data and systems, while ensuring compliance with industry standards and regulations. The Center for Internet Security (CIS) offers specific recommendations for firewall hardening best practices.

These include implementing secure authentication methods, disabling unnecessary services and protocols, restricting traffic from untrusted sources, establishing encryption protocols, and keeping operating systems up-to-date with patched vulnerabilities. Applying these best practices for firewall hardening can effectively thwart attackers from exploiting known weaknesses in the system’s security configuration or code base.

4. Set the Firewall to Deny All Inbound and Outbound Traffic by Default.

Setting the firewall to deny all inbound and outbound traffic by default often referred to as an “implicit deny” rule, is indispensable for ensuring that only legitimate traffic is allowed through the firewall. It means that unless a particular type of traffic is explicitly permitted, it is automatically blocked.

The importance of this strategy cannot be overstated. It provides a base level of protection against unauthorized access attempts and malicious activities. By default, everything is locked down, and only traffic that has been explicitly granted permission is allowed to pass. This approach minimizes the potential attack surface, as cyber threats need to pass through specific, heavily monitored checkpoints.

Moreover, denying all traffic by default simplifies the process of managing and monitoring network traffic. Administrators can focus on reviewing and auditing the allowed traffic flows, rather than sifting through an abundance of logs stemming from various, potentially unnecessary, sources. In a nutshell, this practice represents a proactive stance on network security – barring all access until the legitimacy and safety of the traffic have been confirmed. A secure network is not merely about blocking malicious traffic but also about controlling and managing authorized access.

5. Allow Only Necessary Ports Required for Your Application

Applications typically communicate with each other and with users via specific network ports. Therefore, allowing only the necessary ports means that only the communications needed for the application to function are permitted. This approach ensures that if an application doesn’t need to talk to another application or user, it won’t have the ability to. In other words, it prevents unnecessary communications and potential security vulnerabilities.

By strictly allowing only the necessary ports, you reduce the likelihood of an attacker successfully exploiting a vulnerability in the system. If a port that’s not needed for your application is left open, it can become a door for malicious activities. So, closing unnecessary ports is like sealing off unused doors in a building, making it harder for intruders to find a way in.

6. Monitor Active Connections at All Times to Identify Any Unusual Activity

The process of monitoring active connections allows administrators to quickly detect and respond to any unusual or suspicious activity on the network. In essence, it is the equivalent of having a burglar alarm in a building that triggers an alert when unauthorized access is attempted.

Any anomalies in the traffic patterns, such as unexpected data transfers, connections from unfamiliar locations, or sudden spikes in traffic, could be indicative of a security breach or an attempted hack. Continuous monitoring enables the immediate detection of these anomalies, prompting swift action to mitigate potential threats and minimize damage to the network.

The importance of monitoring cannot be understated in the context of modern cybersecurity. With the ever-evolving landscape of threats, having a real-time overview of network activity enables security teams to stay one step ahead of potential intruders. By identifying and addressing unusual activity promptly, organizations can significantly enhance their network security and protect their assets from cyber threats.

7. Utilize Secure Protocols Such as SSH, SFTP, HTTPS, or TLS Where Possible

Utilizing secure protocols in network communication, such as SSH, SFTP, HTTPS, or TLS, provide essential layers of encryption, making it exceedingly challenging for potential intruders to intercept and decipher the data being transferred.

SSH, or Secure Shell, facilitates secure remote login and other secure network services over an insecure network. It replaces less secure remote login protocols like Telnet, providing robust authentication and secure encrypted data communication. SFTP, or Secure File Transfer Protocol, allows for secure and reliable data transfer, mitigating the risk of data tampering, leakage, or interception during transit.

HTTPS, or Hypertext Transfer Protocol Secure, secures communication over a computer network, particularly on the internet. It uses encryption based on either SSL (Secure Sockets Layer) or TLS (Transport Layer Security). These protocols authenticate the network’s servers, safeguarding the privacy and integrity of the data being exchanged.

By incorporating secure protocols into your network communication, you create a formidable line of defense against cyber threats. It’s akin to equipping a building with bulletproof windows and reinforced doors – the building becomes difficult to breach without specialized tools and knowledge.

8. Use Firewalls to Segment Networks to Limit the Spread of Malware

Firewalls serve as the first line of defense in network security infrastructure. A key practice in enhancing this defense is to segment networks using firewalls, thereby limiting the potential spread of malware. Network segmentation refers to the division of a computer network into smaller parts or ‘segments.’ This technique is akin to compartmentalizing a ship; if one part gets flooded, the entire ship doesn’t sink.

By segmenting a network, organizations can limit an attacker’s ability to move laterally through their systems. If an attacker manages to breach one segment, the damage is contained to that specific segment and can’t spread across the entire network. This is especially important in the context of malware, which seeks to infect as many systems as possible.

When networks are appropriately segmented, the impact of a malware attack is significantly reduced. Even if malware infiltrates one segment, the other segments remain unaffected, allowing an organization to mitigate the effects of the attack and recover more quickly. Furthermore, segmenting the network also allows for easier tracking and removal of the malware, as it is confined to a specific area.

9. Use Intrusion Detection and Prevention Systems (IDS/IPS) on NGFW

IDS is a passive security system that monitors network traffic. It alerts the system administrators when it detects suspicious activities or any violation of the system’s security policies. IDS is like a vigilant night watchman, always keeping an eye out for any potential threats and raising the alarm when something is amiss.

On the other hand, IPS is an active security system. It not only identifies potential threats like IDS but also takes necessary actions to prevent them. When IPS detects an attempted breach, it can block traffic from the offending IP address, disconnect the user, or even change the system’s security configuration to better protect against such intrusions. Think of IPS as a well-trained guard dog, capable of not only detecting a threat but also taking action to neutralize it.

Incorporating IDS/IPS into NGFWs enhances the functionality of a traditional firewall. While firewalls traditionally block unauthorized access based on IP addresses and ports, IDS/IPS systems monitor and analyze the actual content of the network traffic. This provides a more comprehensive and nuanced approach to securing a network, as it can detect a wider range of threats, including zero-day attacks and advanced persistent threats.

10. Leverage on Firewall Auditing Tools

Firewall auditing tools play an essential role in ensuring the security and integrity of a firewall. They perform automatic and continuous audits of firewall rules, configurations, and changes. This is critical because incorrect or outdated rules can leave a network vulnerable to attacks, breaches, and data loss.

Firewall auditing tools not only identify and report misconfigurations, but they also provide actionable insights to rectify them, thereby strengthening the overall security posture. For instance, they can detect unused or overly permissive rules that increase the risk of unauthorized access. By promptly addressing such issues, organizations can bolster their defenses against potential threats.

Additionally, these tools facilitate compliance with various regulatory standards such as PCI DSS, HIPAA, and SOX, which mandate regular firewall audits. They automate the otherwise cumbersome and resource-intensive process of manual audits, saving time, reducing human errors, and ensuring a more accurate and thorough review.

Common Firewall Misconfigurations

Here are some of the most common firewall misconfigurations that your should be aware of:

  1. Any-Any Configuration: An example of an insecure configuration is the “any-any” rule, which allows unrestricted traffic through the firewall. This configuration grants unlimited access to the entire network, including sensitive resources like databases and web servers. For example:

    • Source IP Address:

    • Source Port: Any

    • Destination IP Address:

    • Destination Port: Any

  1. Insecure Protocols: Another insecure firewall configuration involves the use of vulnerable protocols. This includes outdated versions of TLS and SSL, as well as unsecured HTTP communication. These protocols can be easily intercepted by hackers, granting them access to confidential information within an organization’s network.

  2. Overly Permissive Access Control List (ACL): An overly permissive Access Control List (ACL) is a security misconfiguration where the ACL contains too many entries or broad permissions, allowing access to restricted resources. This can lead to threat actors gaining unauthorized access to sensitive information or executing malicious code on systems they shouldn’t have access to. To address policy violations, it is important to review and update existing firewall rules and policies, removing unnecessary entries and tightening the existing ones as needed.

  3. Failure to Restrict Outbound Traffic: When network firewalls do not monitor and restrict outbound traffic, attackers and malicious software can easily exfiltrate sensitive data or communicate with their control servers. Even if a network is well-protected against incoming threats, the lack of proper outbound traffic monitoring creates an open window for attackers.


Establishing robust firewall protocols and adhering to best practices is not merely a suggestion, but a necessity in the modern digital landscape. However, merely setting up firewalls isn’t sufficient. Regular audits, updates, and penetration testing are vital to keep firewalls updated and capable of combating emerging threats.

Penetration testing services, like those offered by Securinc, provide a comprehensive solution for maintaining optimal network security. Securinc’s expert team can simulate real-world attacks in a controlled environment to identify vulnerabilities in the system, including firewall misconfigurations, and provide specific, actionable recommendations to bolster your network’s security.

With Securinc, you can stay a step ahead, ensuring that your firewalls are not only well-configured but also prepared for the ever-evolving landscape of digital threats. Trusting in Securinc translates to a commitment for maintaining the highest level of security for your network.

Our Latest Update

News and Insights

× Whatsapp Us!