When the system config does not match the hardware setup, the “Network Interface Mismatch” in pfSense occur. The article explains quick solutions to the issue. At Bobcares, with our pfSense Support Services, we can handle your issues.
Overview
More on “Network Interface Mismatch” in pfSense
The “Network Interface Mismatch” issue in pfSense typically occurs when the physical network interfaces on the hardware do not match the config in pfSense. This can happen for various reasons. The following section explores various causes for the error and the fixes for each cause.
Causes & Fixes
Cause 1: Interface Configuration Mismatch
The configuration file still refers to old interfaces (e.g., em0), which are no longer available in the current hardware setup.
Fix: We must update the config in order to fix the issue. The steps are as follows:
i. Check that we have a backup of the pfSense settings before making any changes.
ii. In a text editor, open the configuration file (/etc/inc/config.xml) and locate the old interfaces (e.g., em0) that are no longer present in the new hardware setup.
iii. Refresh the settings file to reflect the new hardware settings.
iv. Save the new config file to ensure that changes are kept even after a reboot.
Cause 2: VLAN Configuration Issues
This issue can be caused by leftover VLAN settings that reference out of date interfaces. When VLANs are not properly changed to match the new hardware setup, a mismatch exists between the VLAN settings and the real interfaces on the system.
Fix: Remove any VLAN settings which use old interfaces and restart the system. The steps are as follows:
i. Initially, we need to backup the setup.
ii. Then, identify the Old Interfaces.
iii. Now, update the VLAN config by adjusting VLAN settings to match the new hardware. We can rename or remove old interface references and updating assignments.
iv. Save Changes.
v. Lastly, reboot the System.
Cause 3: Boot Loader Configuration Issues
Missing bios for USB devices can cause the system to fail to boot, requiring interface reassignment.
Fix: We must include a firmware directives to /boot/loader.conf.local to ensure the USB devices are recognized during boot. The steps are as follows:
i. Backup the config.
ii. Identify Missing Firmware. Check system logs or manually inspect USB devices to find missing firmware.
iii. Add Firmware Directives by editing /boot/loader.conf.local and add lines like usbdev_load=”YES” for each missing firmware.
iv. Save Changes and Reboot the System.
Cause 4: Interface Mismatch Detection
During boot, the system checks for interfaces and prompts user to reassign them if there is a mismatch.
Fix: To avoid the prompt, comment out the interface mismatch detection code in /etc/rc.bootup. The steps are as follows:
i. Backup the setup.
ii. Open the /etc/rc.bootup file in a text editor and look for the interface mismatch detecting function. This function usually begins with the if [-n “$INTERFACE_MISMATCH”]; then.
iii. To disable the interface mismatch detection function, put a # sign at the beginning of the line.
iv. Save the changes and reboot the system.
Cause 5: Traffic Shaping and Limiters
Outdated traffic shaping settings can cause low throughput.
Fix: Check and adjust the traffic shaping options to ensure they are suitable for the available bandwidth. The steps are as follows:
i. Check the traffic shaping settings, including bandwidth limits, queue settings, and policies.
ii. Use online tools or speed tests to find the actual available bandwidth.
iii. Adjust the bandwidth limits in the traffic shaping settings to match the measured bandwidth, setting appropriate upload and download limits.
iv. Improve queue settings, like queue size and discipline (e.g., CoDel, FQ_CoDel, or PIE), to reduce bufferbloat and latency.
v. Create or update traffic shaping policies to prioritize important traffic and limit non-essential traffic by applications, users, or IP addresses.
vi. Test network performance and monitor traffic shaping statistics after applying changes.
Cause 6: Duplex Mismatch
Duplex conflicts between the firewall and the upstream link can result in low throughput and interface issues.
Fix: Check that the firewall’s speed and duplex factors match those of the upstream link. The steps are as follows:
i. Check the duplex settings of both devices using the device config or tools like ethtool or mii-tool.
ii. Set both devices to the same duplex mode, either manually or by enabling auto-negotiation.
iii. Ensure the duplex settings match using the device config or tools like ethtool or mii-tool.
iv. Test the connection to ensure it works correctly and has no interface errors.
Cause 7: WAN Connection Issues
Issues with the WAN connection can result in limited bandwidth.
Fix: We need to test WAN as given below:
i. Connect the modem’s Ethernet port to a switch port.
ii. Connect a device (e.g., laptop) to another switch port.
iii. Test the internet connection on the device. If stable with good throughput, the issue is likely with the firewall.
iv. Review the firewall settings, including WAN interface, traffic shaping, and MTU settings.
v. Connect the firewall directly to the switch and test the WAN connection. If issues persist, the firewall’s WAN interface may have a hardware problem.
Cause 8: MTU Issues
An MTU mismatch between the firewall and the upstream link can result in packet breakup and loss.
Fix: To overcome MTU difficulties, make sure the firewall’s and upstream link’s MTU settings match. This can be accomplished by setting the MTU of the firewall to the same value as the upstream link. Consider using MSS clamping for VPN networks to reduce fragmentation and assure suitable packet transmission.
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Conclusion
Understanding these causes and running the right changes will successfully fix the “Network Interface Mismatch” issue in pfSense. In conclusion, the article explains about different fixes from our Tech team for different issues that may lead to the error.
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