Efficient Privacy Preserving Multicast DNS Service Discovery

In today´s local networks a significant amount oftraffic is caused by Multicast DNS Service Discovery (mDNSSD),a prevalent technique used for configurationless servicedistribution and discovery. It allows users to offer and use serviceslike device synchronization, file sharing, and chat, when joininga local network without any manual configuration. While this isvery convenient, it requires the public exposure of the offeringand requesting identities along with information about the offeredand requested services, even when services do not need to bepublic. Some of the information published by the announcementscan be very revealing, including complete lists of family members.Another problem is the huge amount of multicast traffic caused,which is especially relevant for large WiFi networks.In this paper we present a privacy extension that does notpublish private information and reduces the number of packetssent while still not requiring any network configuration except foran initial pairing per pair of users. A key feature of our solutionis the ease of upgrading existing systems, a must for widespreaddeployment and acceptance. We developed an implementationbased on the open-source Avahi daemon to show the feasibilityof our privacy extension. Our solution grants tunable privacyand reduces multicast traffic without affecting user experience.Index Terms-Privacy, DNS, Multicast, Service Discovery.