Firewall best practices for securing networks

A network firewall is an essential component of a cybersecurity strategy. As the first defense against external threats, it prevents unauthorized access to your network and ensures that sensitive information remains secure.

Yet, deploying a firewall isn't enough to guarantee complete protection. Following a set of best practices for firewall rules configuration during deployment, maintenance, configuration, user access control, intrusion detection, prevention, logging, and auditing is necessary.

Let's take a closer look at good firewall practices when securing networks.

1. Regular firewall maintenance

Maintaining a firewall is critical to ensure that it provides the necessary security and network compliance. Only an up-to-date, properly configured, and optimized firewall can protect against cyber threats.

How to ensure your firewall is up to date

Whichever firewall software you're using, it's constantly being updated to address emerging threats and newly discovered vulnerabilities. Therefore, it's important to regularly check for software updates and patches and install them as soon as they're available.

In addition, if your enterprise uses a hardware firewall on top of software updates, it's important to look into the firmware. While not as frequently released, firmware updates must be up-to-date to provide the highest level of resistance against hacking attempts.

Configure your firewall with industry best practices

A firewall will be more effective if best practices are considered when implementing it. Here are some of those that you could use:

1. Start with a default deny policy. As a rule, your firewall should deny all traffic unless explicitly allowed.

2. Implement the principle of least privilege. Only the minimum level of access should be allowed for users to function.

3. Segment your network. The network should be divided into separate segments, and different firewall policies should be applied to each.

It's also important to ensure that your firewall configurations block insecure protocols and traffic from suspicious sources.

2. Creating a firewall policy

A firewall policy is a set of rules determining how incoming and outgoing network traffic is handled. To form a policy, these rules should be defined and ensured that only authorized traffic is allowed through the firewall, while unauthorized or malicious traffic should be blocked.

Importance of a firewall policy

A firewall policy helps ensure the firewall is working as intended. It defines the rules for what traffic is allowed to pass through the firewall and what is blocked. Simultaneously, it enforces the same security policy rules across all users on the network.

Key components of a firewall policy

A firewall policy should be extensive and cover multiple areas determining its response to various network traffic types. The key components of a firewall policy should include:

• Description of the network environment. This should allow a full outline of various network segments and their purposes.
• A list of allowed and blocked traffic types. This information can immediately be enforced directly on a firewall by allowlisting or denylisting traffic like HTTP, FTP, or others.
• A list of allowed sources and destinations. The IP addresses, networks, or domains allowed to be reached should be listed in a privacy policy.
• User access control policies. Allowed activities of legitimate users should be documented, meaning that everything that is permitted for each user type should be noted in a firewall policy.
• Logging and auditing policies. When traffic matches a rule, every performed action on the network should be logged, and it's important to outline how the logs will be kept and saved.
• Intrusion detection and prevention policies. Security measures are put in place by organizations to detect and prevent unauthorized access to their computer networks and systems.
  
  

By defining these key components, a firewall policy can effectively contribute to an organization's security and helps ensure that a firewall is well-documented and used to its fullest potential.

Steps to creating a firewall policy

A firewall policy will be the main document dictating how a firewall allows or denies traffic to and from your network. Here are the steps you can follow to create a firewall policy:

Identify the needs of your organization. Identifying the assets that need to be protected and threats your organization is likely to face. This should help determine the acceptable risk level and act as the basis for the security policy.

Determine the scope of your firewall policy. By defining the boundaries of the network, including internal and external network segments, a firewall security policy can be better specified, including traffic from internal and external sources.

Establish guidelines for user access control. Defining the rules and procedures governing how users are granted and managed access to resources within an organization establishes a transparent and universal rule set across all networks.

Define rules for blocking and allowing traffic. Clear indications of what traffic is allowed and which is denied help to maintain the security and integrity of an organization's network and resources.

Determine how you will monitor and audit your firewall. This helps to ensure the effectiveness and reliability of your organization's security measures. It's essential for maintaining a secure and reliable network against potential threats and vulnerabilities.   

3. User access control enforcement

User access control is a security mechanism regulating which users or system processes have access to certain resources or data. Defining user permissions, roles, and privileges can be defined based on the principle of least privilege.

How user access control works

User access control uses various mechanisms to regulate access to resources or data based on the user's identity, permissions, and roles. It involves three main steps:

• Authentication. The user must prove their identity through various factors.
• Authorization. Once the user is authenticated, the access control system checks their permissions and roles to determine whether they can access requested resources.
• Enforcement. If the user is authorized, the access control system grants access; if not, access is denied.
  
  

By implementing user access control, organizations can better protect their sensitive data and resources, prevent unauthorized access and ensure compliance.

Methods of managing user access control

There are several methods for managing user access control, including role-based access control (RBAC), mandatory access control (MAC), and attribute-based access control (ABAC).

RBAC — assigns user roles to control access to resources

ABAC — controls access based on user attributes like team or job title

MAC — controls access based on security policies

It's important to choose the method that best suits your organization's needs and ensure that all users are aware of the access control policies in place.

4. Intrusion detection and prevention

An intrusion detection and prevention system (IDPS) is essential for detecting and preventing unauthorized access to your network. It helps to secure against attacks like malware, viruses, and hacking attempts that could compromise network security.

How intrusion detection works

Intrusion detection and prevention works by monitoring network traffic and system activity for unusual or suspicious behavior. It indicates unusual behavior or patterns that may indicate a security threat.

There are two main types of IDPS:

Intrusion detection systems — focusing on network traffic monitoring and system logs for signs of suspicious activity.

Intrusion prevention systems — these systems go one step further than IDS by actively blocking or mitigating identified threats before they can cause harm.

The goal of intrusion detection systems is to detect and respond to cybersecurity threats before they cause damage to the network or system. It's a critical component of any organization's cybersecurity infrastructure as it helps detect and prevent cyberattacks.

5. Logging and auditing

Logging and auditing are critical aspects of firewall rules that provide visibility into network activity. Extensive firewall logs can provide in-depth insight into a network's usage and help to trace back security breaches. For most compliance certificates, auditing allows security stakeholders to review logs and identify security issues that must be addressed.

Importance of logging and auditing when using a firewall

Logging and auditing are critical for monitoring firewall activity and ensuring network security. As firewalls serve as the main defense against unauthorized external connections, firewall logs are one of the main assets when evaluating the scope of risks.

Regular log reviews allow network administrators to remove unused and duplicate devices from the firewall rule base to ensure optimal firewall performance. These audits provide an additional layer of protection by reviewing access controls, policies, and configurations to ensure they align with security best practices.

How to implement a decent logging and audit system

Here are the best practices for implementing a well-rounded logging and audit system when using a firewall.

1. Centralized logging

Deploying a centralized logging system can simplify the log analysis process. Consolidating all logs from multiple sources makes detecting patterns and security breaches easier. It also makes it much easier to form log reports for compliance audits.

2. Use a firewall for monitoring

Logging and auditing all traffic flowing through the firewall are helpful tools when identifying malicious traffic patterns. Therefore, all traffic should be logged and audited, no matter its origin or destination.

3. Secure the log storage

Logs contain highly sensitive data, so their storage should be very secure. It should be protected with appropriate access controls and encryption to ensure only authorized personnel can access them. 

Key takeaways for firewall best practices

Network security is more important than ever, so firewalls are crucial when securing networks. Yet, they must be properly configured, deployed, and managed to ensure it's effective.

Firewall policies should be aligned with the company's security policy goals, and the firewall rule base should be regularly reviewed and updated. In addition, network teams must ensure that the firewall is optimized for the network's security needs. Implementing these practices can help organizations meet their security policy goals and protect against potential security threats.