🧱🔥Simplifying Vulnerability Scanning Across Multiple DMZs on a Fortinet Firewall🚒

In today’s complex network environments, businesses often use multiple DMZs to isolate different public-facing services for enhanced security. However, running vulnerability scans across these DMZs can become challenging, particularly when managing access rules on a Fortinet firewall. Many administrators resort to creating multiple firewall rules—one for each DMZ—leading to unnecessary complexity and potential misconfigurations.

Fortunately, Fortinet firewalls provide a streamlined way to enable secure access for vulnerability scanners to multiple DMZs using a single firewall rule. This article explains how to achieve this, along with the benefits and best practices.

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Why Use a Single Rule for Scanner Access?

A single firewall rule simplifies management, reduces administrative overhead, and minimizes the risk of errors. With a centralized approach, you can easily update access policies without needing to adjust multiple rules, making your network both secure and scalable.

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Step-by-Step Configuration

1. Group the DMZ Interfaces or Subnets

Begin by organizing the DMZs into a group:

• Navigate to Policy & Objects > Addresses on your Fortinet firewall.

• Create address objects for each DMZ subnet or IP range.

  • Example: If DMZ1 has a subnet 192.168.10.0/24 and DMZ2 has 192.168.20.0/24, define separate objects for these networks.

• Next, create an address group:

  • Navigate to Policy & Objects > Address Groups.

  • Add the DMZ address objects to the group.

This address group will act as the destination in the firewall rule.

2. Define the Vulnerability Scanner as a Source

Identify the vulnerability scanner’s IP or IP range and create an address object for it:

• Go to Policy & Objects > Addresses and define an object for the scanner, e.g., Scanner-192.168.1.50.

3. Create a Unified Firewall Policy

With the source and destination objects in place, create a single policy for the scanner:

• Navigate to Policy & Objects > IPv4 Policy.

• Click “Create New” and configure the rule as follows:

  • Source: The scanner’s address object.

  • Destination: The DMZ address group.

  • Service: Use “ALL” for unrestricted scanning or specify required ports (e.g., TCP/UDP 80, 443).

  • Action: Allow.

  • Schedule: Optionally, restrict scanning to specific times to minimize network impact.

Enable logging for visibility into scanner activity and to aid in troubleshooting.

4. Test and Monitor

Verify that the vulnerability scanner can access all intended DMZs and that the policy works as expected. Monitor logs to ensure compliance with security policies.

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Benefits of a Single-Rule Approach

1. Simplification: Managing a single rule instead of multiple ones reduces complexity and saves time.

2. Scalability: Adding a new DMZ requires updating only the address group—not creating new policies.

3. Improved Security: A single, well-audited rule ensures consistent enforcement of access controls.

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Best Practices for Secure Vulnerability Scanning

1. Follow the Principle of Least Privilege
   Restrict the scanner’s access to only the necessary ports and protocols. Overly permissive rules increase risk.

2. Segmentation and Isolation
   Ensure proper DMZ segmentation to prevent unintended access to internal resources.

3. Monitor Network Performance
   Vulnerability scans can generate significant traffic. Ensure your Fortinet firewall and network infrastructure can handle the load.

4. Log and Audit Regularly
   Enable logging on the rule to track activity and maintain an audit trail.

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Wrap

Providing access for a vulnerability scanner across multiple DMZs doesn’t need to be a complicated task. By leveraging Fortinet’s address groups and centralized policies, you can enable scanning with a single rule, simplifying management and enhancing scalability.

This approach ensures that your vulnerability scanner has the necessary visibility to detect and address potential weaknesses while keeping your network architecture clean and secure. For businesses striving for operational efficiency, consolidating rules is a crucial step towards robust and manageable cybersecurity practices.

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