Chapter 17. Troubleshooting

Table of Contents

17.1. Interfaces are not detected
17.2. After replacing my current firewall with m0n0wall using the same public IP, m0n0wall cannot get an Internet connection.
17.3. No Link Light
17.4. Cannot Access webGUI
17.5. Cannot Access Internet from LAN after WAN Configuration
17.5.1. Ping m0n0wall LAN IP
17.5.2. Check m0n0wall's WAN IP
17.5.3. Ping m0n0wall's WAN IP
17.5.4. Ping m0n0wall's WAN's gateway IP
17.5.5. Ping an IP address on the Internet
17.5.6. Ping a DNS name that responds to pings
17.6. Troubleshooting Firewall Rules
17.6.1. Reading raw IPFilter logs
17.7. Troubleshooting Bridging
17.8. Troubleshooting IPsec Site to Site VPN
17.9. Troubleshooting Solid Freezes
17.9.1. Shared IRQ's
17.9.2. BIOS Version and Settings
17.9.3. Hardware Issues

This chapter outlines some of the more common problems you may experience when using m0n0wall, and how to troubleshoot and resolve them.


To allow yourself access to log messages even if the m0n0wall device is unreachable, you can send syslog messages to a remote syslog server. This way you can see many logs that might help identify the problem. See the section on Logging for more information.

17.1. Interfaces are not detected

First check your BIOS settings for a "Plug and Play OS" or "OS" setting. For "Plug and Play OS", set it to "no" or "disable". If there is an "OS" setting, typically you can and should set it to "other". This most always fixes the problem.

If that doesn't resolve it, try to upgrade your system BIOS.

Resetting the BIOS to default settings might help. There have been instances in the past where this has resolved this problem, likely due to some strange BIOS setup from past use of the hardware.

Occasionally other hardware like sound cards, and similar, can prevent some or all of your cards from being detected. Try removing any cards in the system that aren't required, and disabling any unused hardware (USB, parallel port, serial ports, any onboard sound, etc.) in the system BIOS.

Most all Ethernet cards are supported by m0n0wall, but if you still cannot see the network cards, ensure they are supported.