Characterizing Internet Background Traffic from a Spain-Based Network Telescope

Internet background traffic (or Internet Background Radiation, IBR) consists of unsolicited packets. It is traffic usually generated in the preliminary phases of attacks by computers making enumerations of targets and available services, sent as responses to denial of service attacks, or sent by mistake due to incorrect configurations and commands. Capturing and analysing this traffic enables the observation of Internet activity and serves as an important tool for identifying new types of attacks and attackers. This traffic is captured by “network telescopes”, nodes that advertise blocks of unused IP addresses and store the traffic sent to them. This article studies the traffic received by a network telescope located in Spain during 2023, with more than 4.7 billion packets and 362.39 GB of information. A statistical breakdown of the packets by protocol shows that TCP accounts for 95.96%, UDP for 3.74%, and ICMP for 0.51%. In addition, the behaviour of the traffic generators targeting the telescope’s addresses is examined, and the main attacks – such as NTP and DNS reflection – are analysed. The characteristics of the traffic are compared with those of previous studies, highlighting changes in behaviour and the most common attacks.