Recent research efforts have shown that peer-topeer (p2p) mechanisms incorporate a potential that goes well beyond simple file sharing. Compared to the classic client-server architecture, these systems do not suffer from a single point of failure.

However, there is still the danger that an adversary is able to attack a specific subpart of the system. This is especially true for structured p2p networks like Chord. A well targeted attack could cause disruptions in its global ring structure and result in severe performance degradations, loss of resources or major malfunctions.

In this paper we introduce a self-protecting approach to prevent such disruptions before they actually happen. However, since it is practically impossible to avoid all failures and attacks, we also present selfrepairing algorithms, which are able to automatically detect disruptions and initiate appropriate countermeasures to reestablish the structure of the overlay.