Kalman Graffi

LifeSocial.KOM: A secure and P2P-based solution for online social networks

The phenomenon of online social networks reaches millions of users in the Internet nowadays. In these, users present themselves, their interests and their social links which they use to interact with other users. We present in this paper LifeSocial.KOM, a p2p-based platform for secure online social networks which provides the functionality of common online social networks in a totally distributed and secure manner. It is plugin-based, thus extendible in its functionality, providing secure communication and access-controlled storage as well as monitored quality of service, addressing the needs of both, users and system providers. The platform operates solely on the resources of the users, eliminating the concentration of crucial operational costs for one provider. In a testbed evaluation, we show the feasibility of the approach and point out the potential of the p2p paradigm in the field of online social networks.

Practical security in p2p-based social networks

The peer-to-peer paradigm is used in more and more advanced applications. One of the next areas that promise a success for the p2p paradigm lies in the upcoming trend of social networks. However, several security issues have to be solved in p2p-based social network platforms. We present in this paper a practical solution that establishes a trust infrastructure, enables authenticated and secure communication between users in the social network and provides personalized, fine grained data access control. We implemented our solution in a p2p based platform for social networks and show that the solution is practical and lightweight both in time consumption and traffic overhead.

A Distributed Platform for Multimedia Communities

Online community platforms and multimedia content delivery are merging in recent years. Current platforms like Facebook and YouTube are client-server based which result in high administration costs for the provider. In contrast to that peer-to-peer systems offer scalability and low costs, but are limited in their functionality.In this paper we present a framework for peer-to-peer based multimedia online communities. We identified the key challenges for this new application of the peer-to-peer paradigm and built a plugin based, easily extendible and multi-functional framework. Further, we identified distributed linked lists as valuable data structure to implement the user profiles, friend lists, groups, photo albums and more. Our framework aims at providing the functionality of common online community platforms combined with the multimedia delivery capabilities of modern peer-to-peer systems, e.g. direct multimedia delivery and access to a distributed multimedia pool.

LifeSocial.KOM: A P2P-Based Platform for Secure Online Social Networks

Online social networks with millions of users are very popular nowadays. They provide a platform for the users to present themselves and to interact with each other. In this paper, we present a totally distributed platform for social online networks based on the p2p paradigm, called LifeSocial.KOM. It provides the same functionality as common online social networks, while distributing the operational load on all participating nodes. LifeSocial.KOM is plugin-based and extendible, provides secure communication and user-based data access control and integrates a monitoring component which allows the users and operators to observe the quality of the distributed system.

Monitoring and management of structured peer-to-peer systems

The peer-to-peer paradigm shows the potential to provide the same functionality and quality like client/server based systems, but with much lower costs. In order to control the quality of peer-to-peer systems, monitoring and management mechanisms need to be applied. Both tasks are challenging in large-scale networks with autonomous, unreliable nodes. In this paper we present a monitoring and management framework for structured peer-to-peer systems. It captures the live status of a peer-to-peer network in an exhaustive statistical representation. Using principles of autonomic computing, a preset system state is approached through automated system re-configuration in the case that a quality deviation is detected. Evaluation shows that the monitoring is very precise and lightweight and that preset quality goals are reached and kept automatically.

AntSec, WatchAnt, and AntRep: Innovative Security Mechanisms for Wireless Mesh Networks

Wireless mesh networks (WMNs) build on user nodes to form the networks routing infrastructure. In particular, the correct forwarding behaviour of each intermediate node on a multihop path from a source node to a destination node is crucial for the functioning of the mesh network. However, current secure routing solutions and misbehaviour detection mechanisms are not sufficient and are mostly inapplicable in mesh networks based on state-of-the-art wireless technology. In particular, hop- by-hop per-link encryption mechanisms break solutions that are based on the overhearing of the wireless channel, which leads to severe problems in the presence of misbehaving nodes. We present AntSec, WatchAnt, and AntRep, which together address the above security gap. AntSec guarantees integrity and authenticity of routing messages, WatchAnt detects misbehaviour in forwarding data messages as well as routing messages and in addition is able to cope with per-link encryption at the MAC layer. AntRep is a reputation management system and helps take punitive action against misbehaving nodes. AntSec, WatchAnt, and AntRep are well suited for WMNs with a quasi-static network topology. Through a thorough evaluation we show the improved routing performance of AntSec working together with WatchAnt and AntRep.

Load balancing for multimedia streaming in heterogeneous peer-to-peer systems

Multimedia streaming of mostly user generated content is an ongoing trend, not only since the upcoming of Last.fm and YouTube. A distributed decentralized multimedia streaming architecture can spread the (traffic) costs to the user nodes, but requires to provide for load balancing and consider the heterogeneity of the participating nodes. We propose a DHT-based information gathering and analyzing architecture which controls the streaming request assignment in the system and thoroughly evaluate it in comparison to a distributed stateless strategy. We evaluated the impact of the key parameters in the allocation function which considers the capabilities of the nodes and their contribution to the system. Identifying the quality-bandwidth tradeoffs of the information gathering system, we show that with our proposed system a 53% better load balancing can be reached and the efficiency of the system is significantly improved.

SkyEye.KOM: An Information Management Over-Overlay for Getting the Oracle View on Structured P2P Systems

In order to ease the development and maintenance of more complex P2P applications, which combine multiple P2P functionality (e.g. streaming and dependable storage), we suggest to extend structured P2P systems with a dedicated information management layer. This layer is meant to generate statistics on the whole P2P system and to enable capacity-based peer search, which helps the individual functionality layers in the P2P application to find suitable peers for layer-specific role assignment. We present in this paper SkyEye.KOM, an information management layer applicable on DHTs, which fulfills these desired functionality. SkyEye.KOM builds an over-overlay, which is scalable by leveraging the underlying DHT, easy to deploy as simple add-on to existing DHTs and efficient as it needs O(log N) hops per query and to place peer-specific information network wide accessible. Evaluation shows that SkyEye.KOM has a good query performance and that the costs for maintaining the over-overlay are very low.

Underlay awareness in P2P systems: Techniques and challenges

Peer-to-peer (P2P) applications have recently attracted a large number of Internet users. Traditional P2P systems however, suffer from inefficiency due to lack of information from the underlay, i.e. the physical network. Although there is a plethora of research on underlay awareness, this aspect of P2P systems is still not clearly structured. In this paper, we provide a taxonomic survey that outlines the different steps for achieving underlay awareness. The main contribution of this paper is presenting a clear picture of what underlay awareness is and how it can be used to build next generation P2P systems. Impacts of underlay awareness and open research issues are also discussed.

Overlay Bandwidth Management: Scheduling and Active Queue Management of Overlay Flows

Peer-to-peer and mobile networks gained significant attention of both research community and industry. Applying the peer-to-peer paradigm in mobile networks lead to several problems regarding the bandwidth demand of peer-to-peer networks. Time-critical messages are delayed and delivered unacceptably slow. In addition to this, scarce bandwidth is wasted on messages of less priority. Therefore, the focus of this paper is on bandwidth management issues at the overlay layer and how they can be solved. We present HiPNOS.KOM, a priority based scheduling and active queue management system. It guarantees better QoS for higher prioritized messages in upper network layers of peer-to-peer systems. Evaluation using the peer-to-peer simulator PeerfactSim. KOM shows that HiPNOS.KOM brings significant improvement in Kademlia in comparison to FIFO and drop-tail, strategies that are used nowadays on each peer. User initiated lookups have in Kademlia 24% smaller operation duration when using HiPNOS.KOM.