Network telescope


A network telescope is an Internet system that allows one to observe different large-scale events taking place on the Internet. The basic idea is to observe traffic targeting the dark address-space of the network. Since all traffic to these addresses is suspicious, one can gain information about possible network attacks as well as other misconfigurations by observing it.
The resolution of the Internet telescope is dependent on the number of IP addresses it monitors. For example, a large Internet telescope that monitors traffic to 16,777,216 addresses, has a higher probability of observing a relatively small event than a smaller telescope that monitors 65,536 addresses.
The naming comes from an analogy to optical telescopes, where a larger physical size allows more photons to be observed.
A variant of a network telescope is a sparse darknet, or greynet, consisting of a region of IP address space that is sparsely populated with "darknet" addresses interspersed with active IP addresses. These include a greynet assembled from 210,000 unused IP addresses mainly located in Japan.