Detect attacks on your network with Maltrail

Place of Use

If you are not able to install Maltrail on a router, switch, or firewall, you need to run the software in passive mode. To operate Maltrail in passive mode, set up the sensor on any computer and then configure it to receive a copy of each packet via a mirror port on the core switch. In this configuration, the sensor is not sitting in the data path, but it will still get enough information to work effectively.

Small networks with a Fritzbox or Speedport as the central component require more effort. The popular DSL routers only allow insights into the incoming packets via a backdoor. This is where manufacturer support ends and tinkering begins. Fortunately, various scripting geniuses have shared their success in accessing the hidden areas of the Fritzbox [2] web interface and other devices [3]. If your router does provide the packet stream in PCAP format, the Maltrail sensor can read and analyze the resulting file with the -i switch.

If this kind of workaround is too much work for you, the only other option is to use Maltrail as a host IDS. In this case, the sensor runs locally on all the servers you want it to monitor. However, Maltrail will no longer be able to protect the entire network, only selected computers.


Not all trails on your network pose a threat. Maltrail also sees services like DynDNS and various HTTP user agents as potential risks. To prevent harmless messages from filling the entire log, you can exclude groups of trails or even entire feeds from the scan.

If you want individual trails to disappear, make them invisible by right-clicking and selecting Hide Threat. Conversely, Maltrail also accepts custom sources with trails that you specify in the configuration file via the CUSTOM_TRAILS_DIR.

Special Case: Windows

Officially Maltrail only runs on Linux and Unix, but with a few tweaks, you can also use a Windows computer as a sensor. The problem is not with Maltrail itself, but with the Pcapy package, which comes with a mass of dependencies. If you don't mind the work, download the Pcapy, Winpcap, and Python source code, as well as the Microsoft Visual C++ Compiler for Python, and compile the package yourself [4]. Once this step is completed, you can launch the sensor on Windows, where it will run in the usual way (Figure 3).

Figure 3: In a roundabout way, Maltrail also runs under Windows.

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