Troubleshooting Policy Based Routing (PBR) Issues In OPNsense

Policy-based routing (PBR) is a powerful feature in OPNsense that allows you to direct network traffic based on specific criteria, ensuring that certain traffic takes a particular path. However, sometimes, PBR rules might seem to be ignored, leading to traffic not being routed as expected. This article delves into a common issue reported in OPNsense where PBR rules are bypassed, and clients are routed through the default gateway instead. We'll explore the problem, the steps to reproduce it, expected behavior, and potential solutions.

Understanding the Issue: Policy Based Routing (PBR) Troubles in OPNsense

The core issue revolves around policy-based routing not functioning correctly after an upgrade to OPNsense 25.1.12. Specifically, clients configured to use PBR are being routed through the default gateway provided by the ISP, effectively bypassing the defined PBR rules. This problem can disrupt network configurations that rely on PBR for specific routing requirements, such as directing traffic through a VPN tunnel or using a different gateway for certain applications. This misdirection of traffic can lead to security vulnerabilities, performance degradation, and accessibility issues for network resources that depend on specific routing configurations. Understanding the root cause of this behavior is crucial for maintaining network integrity and ensuring optimal performance.

To fully grasp the impact, it’s essential to understand how PBR works in OPNsense. PBR allows network administrators to create rules that override the standard routing table, directing traffic based on various criteria such as source IP, destination IP, port, and protocol. When a packet matches a PBR rule, it is routed through the specified gateway instead of the default gateway. This functionality is invaluable for scenarios where different types of traffic need to be routed differently, such as prioritizing traffic for critical applications or securing traffic through VPN tunnels. When PBR rules are ignored, these specific routing requirements are not met, potentially exposing the network to vulnerabilities or performance bottlenecks.

The reported issue highlights the importance of thorough testing after any system upgrade. While upgrades often bring improvements and new features, they can also introduce unexpected behavior due to changes in the underlying system architecture or configurations. In this case, the upgrade to OPNsense 25.1.12 appears to have disrupted the PBR functionality, causing existing rules to be ignored. This underscores the need for a comprehensive testing strategy that includes verifying the functionality of critical network services like PBR after each upgrade. By identifying issues early, administrators can prevent disruptions and ensure a smooth transition to the new version. Addressing this problem promptly is crucial for maintaining the network's intended behavior and preventing any adverse impacts on network operations.

Steps to Reproduce the PBR Bug

To effectively troubleshoot and resolve the PBR issue, it’s crucial to understand the steps to reproduce the bug. The following steps outline the configuration process that leads to the PBR rules being ignored:

1. Configure WireGuard: The initial step involves setting up WireGuard, a modern VPN protocol known for its speed and security. Follow the official OPNsense documentation (https://docs.opnsense.org/manual/how-tos/wireguard-selective-routing.html) to configure WireGuard correctly. This setup is essential as it creates the VPN tunnel that the PBR rules will direct traffic through. Ensure that the WireGuard interface is properly configured and operational before proceeding.
2. Configure the Gateway: Next, you need to configure the gateway that will be used by the WireGuard tunnel. This gateway acts as the exit point for traffic routed through the VPN. The OPNsense documentation (https://docs.opnsense.org/manual/how-tos/wireguard-selective-routing.html#step-6-create-a-gateway) provides detailed instructions on setting up this gateway. It's important to configure the gateway with the correct interface and settings to ensure traffic is properly routed through the WireGuard tunnel.
3. Create a Firewall Rule for PBR: This is a critical step where you define the firewall rule that will trigger the PBR. As described in the OPNsense documentation (https://docs.opnsense.org/manual/how-tos/wireguard-selective-routing.html#step-8-create-a-firewall-rule), this rule specifies the criteria for traffic that should be routed through the WireGuard gateway. This typically involves defining the source IP, destination IP, and other parameters that will match the traffic you want to route through the VPN. The correct configuration of this rule is essential for the PBR to function as intended.
4. Create a Firewall Rule for Non-PBR Internet Access: To ensure that traffic not subject to PBR rules can still access the internet, you need to create another firewall rule that uses the default DHCP gateway provided by your ISP. This rule ensures that regular internet traffic is routed through the standard gateway, while only traffic matching the PBR rule is routed through the WireGuard tunnel. This separation of traffic is crucial for maintaining network functionality and security.
5. Test the PBR Client: Finally, test the PBR client by attempting to access the internet. If the bug is present, the traffic from the PBR client will bypass the configured PBR rule and take the normal route to access the internet through the default gateway. This behavior indicates that the PBR rule is not being applied correctly, and the traffic is not being routed through the WireGuard tunnel as intended. This step confirms the existence of the bug and highlights the need for further investigation and resolution.

By following these steps, you can reliably reproduce the PBR bug in OPNsense 25.1.12 and verify whether the issue is present in your environment. This reproducibility is crucial for troubleshooting and developing a solution.

Expected Behavior vs. Actual Behavior

When policy-based routing (PBR) is correctly configured, the expected behavior is that traffic matching the PBR rules should be routed through the specified gateway. In the context of the reported issue, traffic originating from clients within a defined source IP range and destined for specific public IPs should be routed through the WireGuard VPN tunnel. This ensures that the traffic is encrypted and protected by the VPN, providing an additional layer of security and privacy. The PBR rule acts as a traffic director, selectively routing traffic based on predefined criteria, ensuring that only designated traffic uses the VPN connection. This selective routing is essential for optimizing network performance and security, allowing administrators to control which traffic is protected by the VPN.

However, the actual behavior observed after upgrading to OPNsense 25.1.12 deviates significantly from this expectation. Instead of being routed through the WireGuard tunnel, traffic from the PBR clients bypasses the configured PBR rules and is routed through the default DHCP gateway provided by the ISP. This means that the traffic is not being encrypted by the VPN and is being transmitted over the regular internet connection, potentially exposing it to security risks. This behavior indicates a breakdown in the PBR functionality, where the configured rules are not being applied correctly, leading to traffic being routed through the default gateway instead of the intended VPN tunnel. This misrouting of traffic undermines the purpose of the PBR configuration and can have significant security and privacy implications.

The discrepancy between the expected and actual behavior highlights the severity of the issue. The screenshots provided in the bug report further illustrate the configuration and the bypass of the PBR rules. These visual aids help to clarify the setup and demonstrate that the rules are indeed configured correctly, yet the traffic is not being routed as intended. This visual evidence reinforces the conclusion that there is an underlying issue preventing the PBR rules from functioning properly. The bypassed PBR rules can lead to data breaches, loss of privacy, and compliance violations, making it imperative to identify the root cause and implement a solution promptly. The screenshots serve as a critical piece of evidence, underscoring the need for a thorough investigation and a swift resolution to restore the intended network behavior.

Alternatives Considered

In the context of the reported issue where policy-based routing (PBR) rules are being ignored, the reporter indicated that they had not considered any alternative solutions. This suggests that PBR was deemed the most suitable or only viable method for achieving the desired routing behavior. However, it's beneficial to explore potential alternatives to PBR, even if they were not considered in this specific case, as they might offer insights into different approaches to traffic management and routing.

One potential alternative to PBR is the use of static routes. Static routes are manually configured routes that dictate the path traffic should take based on destination networks. While static routes can be effective in simple network configurations, they become less manageable in complex environments with dynamic routing requirements. Static routes do not provide the same level of granularity and flexibility as PBR, which can route traffic based on various criteria such as source IP, destination IP, and port. The limitation of static routes is that they lack the dynamic nature of PBR, making them less suitable for scenarios where routing decisions need to be made based on real-time traffic conditions.

Another alternative is to use source-based routing, which routes traffic based solely on the source IP address. This approach can be simpler to configure than PBR but is less flexible as it does not consider the destination IP or other factors. Source-based routing might be suitable for scenarios where all traffic from a specific source should be routed through a particular gateway, but it lacks the ability to make routing decisions based on the destination or application. This inflexibility can be a significant drawback in environments where different types of traffic from the same source need to be routed differently.

While PBR offers a powerful and flexible solution for directing network traffic, it's essential to be aware of potential alternatives and their limitations. In this case, the reporter's decision to rely on PBR suggests that it was the most appropriate method for their specific requirements. However, understanding the alternatives can provide a broader perspective on traffic management and routing strategies, enabling administrators to make informed decisions about the best approach for their network environment. Exploring these alternatives, even if not directly applicable, helps in gaining a deeper understanding of network routing principles and the trade-offs involved in different routing methods.

Analyzing the Screenshots

The screenshots provided in the bug report offer valuable insights into the configuration and behavior of the policy-based routing (PBR) setup in OPNsense. Let's delve into each screenshot to understand the key elements and identify potential issues.

The first screenshot displays a broad overview of the firewall rules, highlighting the PBR rule in question. This screenshot shows the rule's position within the rule set, its enabled status, and the basic criteria used for matching traffic. It's crucial to verify that the PBR rule is placed correctly in the rule order, as firewall rules are processed sequentially, and a misplaced rule can prevent the PBR rule from being evaluated. The screenshot also allows us to confirm that the rule is enabled, a simple but essential check to ensure the rule is active. Additionally, the screenshot provides a high-level view of the matching criteria, such as the source and destination IPs, allowing for a quick assessment of the rule's intended scope. This overview is the first step in diagnosing the issue, providing a context for further analysis.

The second screenshot likely focuses on the details of the PBR firewall rule itself. This screenshot would typically show the specific settings configured for the rule, such as the source IP range, destination IP range, protocol, and the gateway selected for routing traffic. A careful examination of this screenshot is essential to ensure that the rule is configured correctly and that the matching criteria accurately reflect the intended traffic. Any discrepancies in the IP ranges, protocol selection, or gateway settings can lead to the PBR rule not being applied as expected. This detailed view is critical for identifying configuration errors that might be causing the PBR rule to be ignored. The accuracy of these settings is paramount to the correct functioning of PBR, making this screenshot a key piece of evidence in the troubleshooting process.

The third screenshot likely showcases the gateway configuration used by the PBR rule. This screenshot would display the settings for the gateway, including the interface, IP address, and other relevant parameters. Verifying the gateway configuration is crucial to ensure that the traffic is being routed to the correct destination. An incorrectly configured gateway can prevent traffic from reaching its intended destination, even if the PBR rule is functioning correctly. This screenshot helps to confirm that the gateway settings are consistent with the PBR rule and that the gateway is operational. The proper configuration of the gateway is a fundamental aspect of PBR, as it determines the exit point for the routed traffic. This screenshot provides the necessary details to validate this crucial component of the PBR setup.

By carefully analyzing these screenshots, we can gain a comprehensive understanding of the PBR configuration and identify potential areas of concern. These visual aids are invaluable for troubleshooting and ensuring that the PBR rules are configured correctly and functioning as intended. The screenshots provide a clear and concise representation of the configuration, facilitating a more efficient and accurate diagnostic process.

Log Files and Additional Context

The bug report mentions checking log files for additional context, which is a crucial step in troubleshooting any network issue. Log files provide a detailed record of system events, including firewall activity, routing decisions, and errors. Analyzing the relevant log entries can help pinpoint the exact moment when the PBR rule is being bypassed and identify any error messages or warnings that might indicate the root cause of the problem. Examining these logs can reveal patterns or anomalies that are not immediately apparent from the configuration screenshots. The systematic analysis of log data is an essential part of the debugging process, often providing the clues needed to resolve complex issues.

In the context of policy-based routing (PBR), the firewall logs are particularly relevant. These logs record the traffic that matches firewall rules, including PBR rules, and the actions taken on that traffic. By examining the firewall logs, you can determine whether traffic is actually matching the PBR rule and, if so, whether the traffic is being routed through the intended gateway. If the logs show that traffic is not matching the PBR rule, it suggests an issue with the rule's matching criteria. If the logs show that traffic is matching the rule but not being routed correctly, it points to a problem with the gateway configuration or the routing process itself. The firewall logs serve as a real-time record of network activity, providing valuable insights into the behavior of the PBR rules.

The additional context provided in the bug report is also essential for understanding the issue. This context includes information about the OPNsense version, the underlying operating system, and any other relevant details about the network environment. Knowing the specific OPNsense version (25.7-amd64 in this case) is crucial because bugs can be specific to certain versions. Similarly, the FreeBSD version (14.3-RELEASE-p1) and OpenSSL version (3.0.17) can provide clues about potential compatibility issues or known bugs in those components. The fact that the system is running in a virtual machine might also be relevant, as virtualization can introduce its own set of challenges. All of this additional context helps to narrow down the possible causes of the issue and guide the troubleshooting process.

By combining the information from the log files with the additional context provided, you can develop a comprehensive understanding of the problem and identify the most likely causes. This holistic approach to troubleshooting is essential for resolving complex network issues and ensuring the stability and reliability of the network. The log files and additional context serve as a vital source of information, enabling a more informed and effective troubleshooting process.

Conclusion: Resolving Policy Based Routing Issues

In conclusion, the issue of policy-based routing (PBR) rules being ignored in OPNsense after upgrading to version 25.1.12 highlights the importance of thorough testing and troubleshooting in network management. This article has explored the problem in detail, outlining the steps to reproduce the bug, the discrepancy between expected and actual behavior, and potential alternative solutions. By analyzing the screenshots and emphasizing the significance of log files and additional context, we've provided a comprehensive guide to diagnosing and resolving this issue. Understanding the nuances of PBR configuration and the potential pitfalls of system upgrades is crucial for maintaining a stable and secure network environment. This systematic approach to troubleshooting empowers network administrators to effectively address PBR issues and ensure that traffic is routed as intended, safeguarding network performance and security.