A honeynet is a special prepared network which is not used in normal
business. It is a kind of playground to watch and learn the tactics of crackers. The only
purpose of a honeynet is to be probed, attacked or compromised. During the operation
other systems may not be harmed by an attack originated within the honeynet. In
this paper the design, realization and operation of a honeynet built within the German
Research Network (DFN) will be described. Concepts for continuously monitoring
and securing the honeynet are introduced. A selection of the results of the operation
phase will be presented as well