Maltrail is a lightweight analysis tool that examines network traffic and raises the alarm if it detects suspicious access or dubious name resolution.
Hundreds of security products vie for the favor of users on the Internet, promising the highest levels of protection. Along with the numerous commercial offerings available for a monthly rate are some free open-source products that aim to expand the basic protection that might already be in place.
Maltrail  is an open source tool that lays in wait on the network and sounds the alarm if a package appears suspicious. It reports its findings but does not intervene. The way Maltrail works is somewhere between an intrusion detection system and a malware scanner. Maltrail uses public blacklists to examine the packages. In Maltrail jargon, the description of a suspicious IP address, web URL, or domain is known as a trail. Feeds are lists of known trails that the Maltrail community keeps up to date.
Maltrail consists of two components. The sensor component sniffs the packets, and the server component collects the alarms from the sensor. In a perfect setup, the sensor component resides on a router or firewall, because these devices get to see the data streams of all network participants. In Figure 1, the sensor resides on a firewall and therefore has access to all the packets passing through. The position of the server does not matter much as long as the sensor and the admin can access it.
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