Security and privacy issues in P2P streaming systems: A Survey
---
paper_title: A modeling framework of content pollution in Peer-to-Peer video streaming systems

paper_content:

Peer-to-Peer (P2P) live video streaming systems are known to suffer from intermediate attacks due to its inherent vulnerabilities. The content pollution is one of the common attacks that have received little attention in P2P live streaming systems. In this paper, we propose a modeling framework of content pollution in P2P live streaming systems. This model considers both unstructured and structured overlays, and captures the key factors including churns, user interactions, multiple attackers and defensive techniques. The models are verified with simulations and implemented in a real working system, Anysee. We analyze content pollution and its effect in live streaming system. We show that: (1) the impact from content pollution can exponentially increase, similar to the random scanning worms, leading to playback interruption and unnecessary bandwidth consumption; (2) content pollution is influenced by peer cooperation, peer degree and bandwidth in unstructured overlays, and topology breadth in structured ones; (3) the structured overlay is more resilient to content pollution; (4) a hybrid overlay result in better reliability and pollution resistance; (5) hash-based chunk signature scheme is most promising against content pollution.
---
paper_title: The pollution attack in P2P live video streaming: measurement results and defenses

paper_content:

P2P mesh-pull live video streaming applications ---such as Cool-Streaming, PPLive, and PPStream --- have become popular in the recent years. In this paper, we examine the stream pollution attack, for which the attacker mixes polluted chunks into the P2P distribution, degrading the quality of the rendered media at the receivers. Polluted chunks received by an unsuspecting peer not only effect that single peer, but since the peer also forwards chunks to other peers, and those peers in turn forward chunks to more peers, the polluted content can potentially spread through much of the P2P network. The contribution of this paper is twofold. First, by way of experimenting and measuring a popular P2P live video streaming system, we show that the pollution attack can be devastating. Second, we evaluate the applicability of four possible defenses to the pollution attack: blacklisting, traffic encryption, hash verification, and chunk signing. Among these, we conclude that the chunk signing solutions are most suitable.
---
paper_title: Pastry: Scalable, Decentralized Object Location, and Routing for Large-Scale Peer-to-Peer Systems

paper_content:

This paper presents the design and evaluation of Pastry, a scalable, distributed object location and routing substrate for wide-area peer-to-peer ap- plications. Pastry performs application-level routing and object location in a po- tentially very large overlay network of nodes connected via the Internet. It can be used to support a variety of peer-to-peer applications, including global data storage, data sharing, group communication and naming. Each node in the Pastry network has a unique identifier (nodeId). When presented with a message and a key, a Pastry node efficiently routes the message to the node with a nodeId that is numerically closest to the key, among all currently live Pastry nodes. Each Pastry node keeps track of its immediate neighbors in the nodeId space, and notifies applications of new node arrivals, node failures and recoveries. Pastry takes into account network locality; it seeks to minimize the distance messages travel, according to a to scalar proximity metric like the number of IP routing hops. Pastry is completely decentralized, scalable, and self-organizing; it automatically adapts to the arrival, departure and failure of nodes. Experimental results obtained with a prototype implementation on an emulated network of up to 100,000 nodes confirm Pastry's scalability and efficiency, its ability to self-organize and adapt to node failures, and its good network locality properties.
---
paper_title: Building peer-to-peer systems with chord, a distributed lookup service

paper_content:

We argue that the core problem facing peer-to-peer Systems is locating documents in a decentralized network and propose Chord, a distributed lookup primitive. Chord provides an efficient method of locating documents while placing few constraints on the applications that use it. As proof that Chord's functionality is useful in the development of peer-to-peer applications, we outline the implementation of a peer-to-peer file sharing system based on Chord.
---
paper_title: Peer-to-peer internet telephony using SIP

paper_content:

P2P systems inherently have high scalability, robustness and fault tolerance because there is no centralized server and the network self-organizes itself. This is achieved at the cost of higher latency for locating the resources of interest in the P2P overlay network. Internet telephony can be viewed as an application of P2P architecture where the participants form a self-organizing P2P overlay network to locate and communicate with other participants. We propose a pure P2P architecture for the Session Initiation Protocol (SIP)-based IP telephony systems. Our P2P-SIP architecture supports basic user registration and call setup as well as advanced services such as offline message delivery, voice/video mails and multi-party conferencing. Additionally, we give an overview of our implementation.
---
paper_title: A Survey of Peer-to-Peer Security Issues

paper_content:

Peer-to-peer (p2p) networking technologies have gained popularity as a mechanism for users to share files without the need for centralized servers. A p2p network provides a scalable and fault-tolerant mechanism to locate nodes anywhere on a network without maintaining a large amount of routing state. This allows for a variety of applications beyond simple file sharing. Examples include multicast systems, anonymous communications systems, and web caches. We survey security issues that occur in the underlying p2p routing protocols, as well as fairness and trust issues that occur in file sharing and other p2p applications. We discuss how techniques, ranging from cryptography, to random network probing, to economic incentives, can be used to address these problems.
---
paper_title: The SPARTA pseudonym and authorization system

paper_content:

This paper deals with privacy-preserving (pseudonymized) access to a service resource. In such a scenario, two opposite needs seem to emerge. On one side, the service provider may want to control, in first place, the user accessing its resources, i.e., without being forced to delegate the issuing of access permissions to third parties to meet privacy requirements. On the other side, it should be technically possible to trace back the real identity of a user upon dishonest behavior, and of course, this must be necessary accomplished by an external authority distinct from the provider itself. The framework described in this paper aims at coping with these two opposite needs. This is accomplished through (i) a distributed third-party-based infrastructure devised to assign and manage pseudonym certificates, decoupled from (ii) a two-party procedure, devised to bind an authorization permission to a pseudonym certificate with no third-party involvement. The latter procedure is based on a novel blind signature approach which allows the provider to blindly verify, at service subscription time, that the user possesses the private key of the still undisclosed pseudonym certificate, thus avoiding transferability of the authorization permission.
---
paper_title: An Efficient System for Non-transferable Anonymous Credentials with Optional Anonymity Revocation

paper_content:

A credential system is a system in which users can obtain credentials from organizations and demonstrate possession of these credentials. Such a system is anonymous when transactions carried out by the same user cannot be linked. An anonymous credential system is of significant practical relevance because it is the best means of providing privacy for users. In this paper we propose a practical anonymous credential system that is based on the strong RSA assumption and the decisional Diffie-Hellman assumption modulo a safe prime product and is considerably superior to existing ones: (1) We give the first practical solution that allows a user to unlinkably demonstrate possession of a credential as many times as necessary without involving the issuing organization. (2) To prevent misuse of anonymity, our scheme is the first to offer optional anonymity revocation for particular transactions. (3) Our scheme offers separability: all organizations can choose their cryptographic keys independently of each other. Moreover, we suggest more effective means of preventing users from sharing their credentials, by introducing all-or-nothing sharing: a user who allows a friend to use one of her credentials once, gives him the ability to use all of her credentials, i.e., taking over her identity. This is implemented by a new primitive, called circular encryption, which is of independent interest, and can be realized from any semantically secure cryptosystem in the random oracle model.
---
paper_title: Application-Layer Traffic Optimization (ALTO) Problem Statement

paper_content:

Peer-to-peer applications, such as file sharing, real-time ::: communication, and live media streaming, use a significant amount of ::: Internet resources. Such applications often transfer large amounts of ::: data in direct peer-to-peer connections. However, they usually have ::: little knowledge of the underlying network topology. As a result, they ::: may choose their peers based on measurements and statistics that, in ::: many situations, may lead to suboptimal choices. This document ::: describes problems related to optimizing traffic generated by peer-to- ::: peer applications and associated issues such optimizations raise in ::: the use of network-layer information.
---
paper_title: SecureStream: An Intrusion-Tolerant Protocol for Live-Streaming Dissemination

paper_content:

Peer-to-peer (P2P) dissemination systems are vulnerable to attacks that may impede nodes from receiving data in which they are interested. The same properties that lead P2P systems to be scalable and efficient also lead to security problems and lack of guarantees. Within this context, live-streaming protocols deserve special attention since their time sensitive nature makes them more susceptible to the packet loss rates induced by malicious behavior. While protocols based on dissemination trees often present obvious points of attack, more recent protocols based on pulling packets from a number of different neighbors present a better chance of standing attacks. We explore this in SecureStream, a P2P live-streaming system built to tolerate malicious behavior at the end level. SecureStream is built upon Fireflies, an intrusion-tolerant membership protocol, and employs a pull-based approach for streaming data. We present the main components of SecureStream and present simulation and experimental results on the Emulab testbed that demonstrate the good resilience properties of pull-based streaming in the face of attacks. This and other techniques allow our system to be tolerant to a variety of intrusions, gracefully degrading even in the presence of a large percentage of malicious peers.
---
paper_title: Understanding P2P-TV Systems Through Real Measurements

paper_content:

In this paper, we consider two popular peer-to-peer TV (P2P-TV) systems: PPLive, one of the today most widely used P2P-TV systems, and Joost, a promising new generation application of which no previous measurement study has been considered. Besides the traditional measurements like the amount of generated traffic for signaling and data transmission, the novel contribution of the paper consists in investigating the content distribution mechanisms. In particular, we evaluate the characteristics of both data distribution and signaling process for the overlay network discovery and maintenance. By considering two or more clients in the same sub-network, we observe the capability of the system to exploit the locality of peers. We also explore how the system adapts to different network conditions. The methodology we develop allows also to identify periodic behavior of the application, highlighting bursts of both data and signaling traffic.
---
paper_title: A Survey of Peer-to-Peer Security Issues

paper_content:

Peer-to-peer (p2p) networking technologies have gained popularity as a mechanism for users to share files without the need for centralized servers. A p2p network provides a scalable and fault-tolerant mechanism to locate nodes anywhere on a network without maintaining a large amount of routing state. This allows for a variety of applications beyond simple file sharing. Examples include multicast systems, anonymous communications systems, and web caches. We survey security issues that occur in the underlying p2p routing protocols, as well as fairness and trust issues that occur in file sharing and other p2p applications. We discuss how techniques, ranging from cryptography, to random network probing, to economic incentives, can be used to address these problems.
---
paper_title: Securing peer-to-peer media streaming systems from selfish and malicious behavior

paper_content:

We present a flexible framework for throttling attackers in peer-to-peer media streaming systems. In such systems, selfish nodes (e.g., free riders) and malicious nodes (e.g., DoS attackers) can overwhelm the system by issuing too many requests in a short interval of time. Since peer-to-peer systems are decentralized, it is difficult for individual peers to limit the aggregate download bandwidth consumed by other remote peers. This could potentially allow selfish and malicious peers to exhaust the system's available upload bandwidth. In this paper, we propose a framework to provide a solution to this problem by utilizing a subset of trusted peers (called kantoku nodes) that collectively monitor the bandwidth usage of untrusted peers in the system and throttle attackers. This framework has been evaluated through simulation thus far. Experiments with a full implementation on a network testbed are part of our future work.
---
paper_title: The pollution attack in P2P live video streaming: measurement results and defenses

paper_content:

P2P mesh-pull live video streaming applications ---such as Cool-Streaming, PPLive, and PPStream --- have become popular in the recent years. In this paper, we examine the stream pollution attack, for which the attacker mixes polluted chunks into the P2P distribution, degrading the quality of the rendered media at the receivers. Polluted chunks received by an unsuspecting peer not only effect that single peer, but since the peer also forwards chunks to other peers, and those peers in turn forward chunks to more peers, the polluted content can potentially spread through much of the P2P network. The contribution of this paper is twofold. First, by way of experimenting and measuring a popular P2P live video streaming system, we show that the pollution attack can be devastating. Second, we evaluate the applicability of four possible defenses to the pollution attack: blacklisting, traffic encryption, hash verification, and chunk signing. Among these, we conclude that the chunk signing solutions are most suitable.
---
paper_title: Defending against eclipse attacks on overlay networks

paper_content:

Overlay networks are widely used to deploy functionality at edge nodes without changing network routers. Each node in an overlay network maintains pointers to a set of neighbor nodes. These pointers are used both to maintain the overlay and to implement application functionality, for example, to locate content stored by overlay nodes. If an attacker controls a large fraction of the neighbors of correct nodes, it can "eclipse" correct nodes and prevent correct overlay operation. This Eclipse attack is more general than the Sybil attack. Attackers can use a Sybil attack to launch an Eclipse attack by inventing a large number of seemingly distinct overlay nodes. However, defenses against Sybil attacks do not prevent Eclipse attacks because attackers may manipulate the overlay maintenance algorithm to mount an Eclipse attack. This paper discusses the impact of the Eclipse attack on several types of overlay and it proposes a novel defense that prevents the attack by bounding the degree of overlay nodes. Our defense can be applied to any overlay and it enables secure implementations of overlay optimizations that choose neighbors according to metrics like proximity. We present preliminary results that demonstrate the importance of defending against the Eclipse attack and show that our defense is effective.
---
paper_title: "Won't You Be My Neighbor?" Neighbor Selection Attacks in Mesh-based Peer-to-Peer Streaming

paper_content:

P2P streaming has grown in popularity, allowing people in many places to benefit from live audio and television services. Mesh-based P2P streaming has emerged as the predominant architecture in realworld use because of its resilience to churn and node failures, scalability, and ease of maintenance. The proliferation of these applications on the public Internet raises questions about how they can be deployed in a secure and robust manner. Failing to address security vulnerabilities could facilitate attacks with significant consequences such as content censorship, unfair business competition, or external impact on the Internet itself. In this paper, we identify and evaluate neighbor selection attacks against mesh-based P2P streaming which allow insider attackers to control the mesh overlay formation and maintenance. We demonstrate the effect of the attacks against a mesh-based P2P streaming system and propose a solution to mitigate the attacks. Our solution is scalable, has low overhead, and works in realistic heterogeneous networks. We evaluate our solution using a mesh-based P2P streaming system with real-world experiments on the PlanetLab Internet testbed and simulations using the OverSim P2P simulator.
---
paper_title: SecureStream: An Intrusion-Tolerant Protocol for Live-Streaming Dissemination

paper_content:

Peer-to-peer (P2P) dissemination systems are vulnerable to attacks that may impede nodes from receiving data in which they are interested. The same properties that lead P2P systems to be scalable and efficient also lead to security problems and lack of guarantees. Within this context, live-streaming protocols deserve special attention since their time sensitive nature makes them more susceptible to the packet loss rates induced by malicious behavior. While protocols based on dissemination trees often present obvious points of attack, more recent protocols based on pulling packets from a number of different neighbors present a better chance of standing attacks. We explore this in SecureStream, a P2P live-streaming system built to tolerate malicious behavior at the end level. SecureStream is built upon Fireflies, an intrusion-tolerant membership protocol, and employs a pull-based approach for streaming data. We present the main components of SecureStream and present simulation and experimental results on the Emulab testbed that demonstrate the good resilience properties of pull-based streaming in the face of attacks. This and other techniques allow our system to be tolerant to a variety of intrusions, gracefully degrading even in the presence of a large percentage of malicious peers.
---
paper_title: Preventing DoS attacks in peer-to-peer media streaming systems

paper_content:

This paper presents a framework for preventing both selfishness and denial-of-service attacks in peer-to-peer media streaming systems. Our framework, called Oversight, achieves prevention of these undesirable activities by running a separate peer-to-peer download rate enforcement protocol along with the underlying peer-to-peer media streaming protocol. This separate Oversight protocol enforces download rate limitations on each participating peer. These limitations prevent selfish or malicious nodes from downloading an overwhelming amount of media stream data that could potentially exhaust the entire system. Since Oversight is based on a peer-to-peer architecture, it can accomplish this enforcement functionality in a scalable, efficient, and decentralized way that fits better with peer-to-peer media streaming systems compared to other solutions based on central server architectures. As peer-to-peer media streaming systems continue to grow in popularity, the threat of selfish and malicious peers participating in such large peer-to-peer networks will continue to grow as well. For example, since peer-to-peer media streaming systems allow users to send small request messages that result in the streaming of large media objects, these systems provide an opportunity for malicious users to exhaust resources in the system with little effort expended on their part. However, Oversight addresses these threats associated with selfish or malicious peers who cause such disruptions with excessive download requests. We evaluated our Oversight solution through simulations and our results show that applying Oversight to peer-to-peer media streaming systems can prevent both selfishness and denial-of-service attacks by effectively limiting the download rates of all nodes in the system.
---
paper_title: Securing peer-to-peer media streaming systems from selfish and malicious behavior

paper_content:

We present a flexible framework for throttling attackers in peer-to-peer media streaming systems. In such systems, selfish nodes (e.g., free riders) and malicious nodes (e.g., DoS attackers) can overwhelm the system by issuing too many requests in a short interval of time. Since peer-to-peer systems are decentralized, it is difficult for individual peers to limit the aggregate download bandwidth consumed by other remote peers. This could potentially allow selfish and malicious peers to exhaust the system's available upload bandwidth. In this paper, we propose a framework to provide a solution to this problem by utilizing a subset of trusted peers (called kantoku nodes) that collectively monitor the bandwidth usage of untrusted peers in the system and throttle attackers. This framework has been evaluated through simulation thus far. Experiments with a full implementation on a network testbed are part of our future work.
---
paper_title: Preventing DDoS Attacks Based on Credit Model for P2P Streaming System

paper_content:

Distributed Denial of Service (DDoS) attack is a serious threat to the Internet communications especially to P2P streaming system. P2P streaming system is vulnerable to DDoS attacks due to its high bandwidth demand and strict time requirement. In this paper, we propose a distributed framework to defense DDoS attack based on Credit Model(CM) which takes the responsibility to identify malicious nodes and categorize nodes into different credit level. We also introduce a Message Rate Controlling Model (MRCM)to control the message rate of a node according to its credit level. Combining CM and MRCS together, our framework can improve the resistibility against DDoS for P2P streaming system.
---
paper_title: Stochastic Graph Processes for Performance Evaluation of Content Delivery Applications in Overlay Networks

paper_content:

This paper proposes a new methodology to model the distribution of finite-size content to a group of users connected through an overlay network. Our methodology describes the distribution process as a constrained stochastic graph process (CSGP), where the constraints dictated by the content distribution protocol and the characteristics of the overlay network define the interaction among nodes. A CSGP is a semi-Markov process whose state is described by the graph itself. CSGPs offer a powerful description technique that can be exploited by Monte Carlo integration methods to compute in a very efficient way not only the mean but also the full distribution of metrics such as the file download times or the number of hops from the source to the receiving nodes. We model several distribution architectures based on trees and meshes as CSGPs and solve them numerically. We are able to study scenarios with a very large number of nodes, and we can precisely quantify the performance differences between the tree-based and mesh-based distribution architectures.
---
paper_title: Graph Based Analysis of Mesh Overlay Streaming Systems

paper_content:

This paper studies fundamental properties of stream-based content distribution services. We assume the presence of an overlay network (such as those built by P2P systems) with limited degree of connectivity, and we develop a mathematical model that captures the essential features of overlay-based streaming protocols and systems. The methodology is based on stochastic graph theory, and models the streaming system as a stochastic process, whose characteristics are related to the streaming protocol. The model captures the elementary properties of the streaming system such as the number of active connections, the different play-out delay of nodes, and the probability of not receiving the stream due to node failures/misbehavior. Besides the static properties, the model is able to capture the transient behavior of the distribution graphs, i.e., the evolution of the structure over time, for instance in the initial phase of the distribution process. Contributions of this paper include a detailed definition of the methodology, its comparison with other analytical approaches and with simulative results, and a discussion of the additional insights enabled by this methodology. Results show that mesh based architectures are able to provide bounds on the receiving delay and maintain rate fluctuations due to system dynamics very low. Additionally, given the tight relationship between the stochastic process and the properties of the distribution protocol, this methodology gives basic guidelines for the design of such protocols and systems.
---
paper_title: Gossiping in distributed systems

paper_content:

Gossip-based algorithms were first introduced for reliably disseminating data in large-scale distributed systems. However, their simplicity, robustness, and flexibility make them attractive for more than just pure data dissemination alone. In particular, gossiping has been applied to data aggregation, overlay maintenance, and resource allocation. Gossiping applications more or less fit the same framework, with often subtle differences in algorithmic details determining divergent emergent behavior. This divergence is often difficult to understand, as formal models have yet to be developed that can capture the full design space of gossiping solutions. In this paper, we present a brief introduction to the field of gossiping in distributed systems, by providing a simple framework and using that framework to describe solutions for various application domains.
---
paper_title: Mesh or Multiple-Tree: A Comparative Study of Live P2P Streaming Approaches

paper_content:

Existing approaches to P2P streaming can be divided into two general classes: (i) tree-based approaches use push-based content delivery over multiple tree-shaped overlays, and (ii) mesh-based approaches use swarming content delivery over a randomly connected mesh. Previous studies have often focused on a particular P2P streaming mechanism and no comparison between these two classes has been conducted. In this paper, we compare and contrast the performance of representative protocols from each class using simulations. We identify the similarities and differences between these two approaches. Furthermore, we separately examine the behavior of content delivery and overlay construction mechanisms for both approaches in static and dynamic scenarios. Our results indicate that the mesh-based approach consistently exhibits a superior performance over the tree-based approach. We also show that the main factors attributing in the inferior performance of the tree-based approach are (i) the static mapping of content to a particular tree, and (ii) the placement of each peer as an internal node in one tree and as a leaf in all other trees.
---
paper_title: Source vs Data-driven Approach for Live P2P Streaming

paper_content:

Live streaming applications are increasing on the Internet. These applications are delay sensitive and need group communication. Presently, protocols designed for this kind of communication do not rely on the classical client/server model used in the Internet but organize the receivers into an overlay network, where they are supposed to collaborate with each other following the peer-to-peer model. Live p2p streaming protocols can be classified in three different categories: source-driven, receiver-driven and datadriven protocols. Each of them manages the overlay differently. In this paper we compare them by simulation to specify what is the most appropriate approach for these protocols. We implement a new simulator of p2p network and we choose two well-known protocols for simulations: a sourcedriven and a data-driven protocol. To our knowledge, our works are the first to compare with the same simulator and scenarii different approaches for live p2p streaming. Our simulations show that nodes organization on the overlay influences drastically network global performances, and data-driven approach seems to be the most appropriate approach for these protocols because it is less sensitive to dynamicity of nodes which is the main problem to resolve for these applications.
---
paper_title: Experimental comparison of peer-to-peer streaming overlays: An application perspective

paper_content:

We compare two representative streaming systems using mesh-based and multiple tree-based overlay routing through deployments on the PlanetLab wide-area experimentation platform. To the best of our knowledge, this is the first study to compare streaming overlay architectures in real Internet settings, considering not only intuitive aspects such as scalability and performance under churn, but also less studied factors such as bandwidth and latency heterogeneity of overlay participants. Overall, our study indicates that mesh-based systems are superior for nodes with high bandwidth capabilities and low round trip times, while multi-tree based systems currently cope better with stringent real time deadlines under heterogeneous conditions.
---
paper_title: Detecting Malicious Peers in Overlay Multicast Streaming

paper_content:

Overlay multicast streaming is built out of loosely coupled end-hosts (peers) that contribute resources to stream media to other peers. Peers, however, can be malicious. They may intentionally wish to disrupt the multicast service or cause confusions to other peers. We propose two new schemes to detect malicious peers in overlay multicast streaming. These schemes compute a level of trust for each peer in the network. Peers with a trust value below a threshold are considered to be malicious. Results from our simulations indicate that the proposed schemes can detect malicious peers with medium to high accuracy, depending on cheating patterns and malicious peer percentages.
---
paper_title: "Won't You Be My Neighbor?" Neighbor Selection Attacks in Mesh-based Peer-to-Peer Streaming

paper_content:

P2P streaming has grown in popularity, allowing people in many places to benefit from live audio and television services. Mesh-based P2P streaming has emerged as the predominant architecture in realworld use because of its resilience to churn and node failures, scalability, and ease of maintenance. The proliferation of these applications on the public Internet raises questions about how they can be deployed in a secure and robust manner. Failing to address security vulnerabilities could facilitate attacks with significant consequences such as content censorship, unfair business competition, or external impact on the Internet itself. In this paper, we identify and evaluate neighbor selection attacks against mesh-based P2P streaming which allow insider attackers to control the mesh overlay formation and maintenance. We demonstrate the effect of the attacks against a mesh-based P2P streaming system and propose a solution to mitigate the attacks. Our solution is scalable, has low overhead, and works in realistic heterogeneous networks. We evaluate our solution using a mesh-based P2P streaming system with real-world experiments on the PlanetLab Internet testbed and simulations using the OverSim P2P simulator.
---
paper_title: SecureStream: An Intrusion-Tolerant Protocol for Live-Streaming Dissemination

paper_content:

Peer-to-peer (P2P) dissemination systems are vulnerable to attacks that may impede nodes from receiving data in which they are interested. The same properties that lead P2P systems to be scalable and efficient also lead to security problems and lack of guarantees. Within this context, live-streaming protocols deserve special attention since their time sensitive nature makes them more susceptible to the packet loss rates induced by malicious behavior. While protocols based on dissemination trees often present obvious points of attack, more recent protocols based on pulling packets from a number of different neighbors present a better chance of standing attacks. We explore this in SecureStream, a P2P live-streaming system built to tolerate malicious behavior at the end level. SecureStream is built upon Fireflies, an intrusion-tolerant membership protocol, and employs a pull-based approach for streaming data. We present the main components of SecureStream and present simulation and experimental results on the Emulab testbed that demonstrate the good resilience properties of pull-based streaming in the face of attacks. This and other techniques allow our system to be tolerant to a variety of intrusions, gracefully degrading even in the presence of a large percentage of malicious peers.
---
paper_title: Experimental comparison of peer-to-peer streaming overlays: An application perspective

paper_content:

We compare two representative streaming systems using mesh-based and multiple tree-based overlay routing through deployments on the PlanetLab wide-area experimentation platform. To the best of our knowledge, this is the first study to compare streaming overlay architectures in real Internet settings, considering not only intuitive aspects such as scalability and performance under churn, but also less studied factors such as bandwidth and latency heterogeneity of overlay participants. Overall, our study indicates that mesh-based systems are superior for nodes with high bandwidth capabilities and low round trip times, while multi-tree based systems currently cope better with stringent real time deadlines under heterogeneous conditions.
---
paper_title: Mesh or Multiple-Tree: A Comparative Study of Live P2P Streaming Approaches

paper_content:

Existing approaches to P2P streaming can be divided into two general classes: (i) tree-based approaches use push-based content delivery over multiple tree-shaped overlays, and (ii) mesh-based approaches use swarming content delivery over a randomly connected mesh. Previous studies have often focused on a particular P2P streaming mechanism and no comparison between these two classes has been conducted. In this paper, we compare and contrast the performance of representative protocols from each class using simulations. We identify the similarities and differences between these two approaches. Furthermore, we separately examine the behavior of content delivery and overlay construction mechanisms for both approaches in static and dynamic scenarios. Our results indicate that the mesh-based approach consistently exhibits a superior performance over the tree-based approach. We also show that the main factors attributing in the inferior performance of the tree-based approach are (i) the static mapping of content to a particular tree, and (ii) the placement of each peer as an internal node in one tree and as a leaf in all other trees.
---
paper_title: CoolStreaming/DONet: a data-driven overlay network for peer-to-peer live media streaming

paper_content:

This paper presents DONet, a data-driven overlay network for live media streaming. The core operations in DONet are very simple: every node periodically exchanges data availability information with a set of partners, and retrieves unavailable data from one or more partners, or supplies available data to partners. We emphasize three salient features of this data-driven design: 1) easy to implement, as it does not have to construct and maintain a complex global structure; 2) efficient, as data forwarding is dynamically determined according to data availability while not restricted by specific directions; and 3) robust and resilient, as the partnerships enable adaptive and quick switching among multi-suppliers. We show through analysis that DONet is scalable with bounded delay. We also address a set of practical challenges for realizing DONet, and propose an efficient member and partnership management algorithm, together with an intelligent scheduling algorithm that achieves real-time and continuous distribution of streaming contents. We have extensively evaluated the performance of DONet over the PlanetLab. Our experiments, involving almost all the active PlanetLab nodes, demonstrate that DONet achieves quite good streaming quality even under formidable network conditions. Moreover, its control overhead and transmission delay are both kept at low levels. An Internet-based DONet implementation, called CoolStreaming v.0.9, was released on May 30, 2004, which has attracted over 30000 distinct users with more than 4000 simultaneously being online at some peak times. We discuss the key issues toward designing CoolStreaming in this paper, and present several interesting observations from these large-scale tests; in particular, the larger the overlay size, the better the streaming quality it can deliver.
---
paper_title: Experimental comparison of peer-to-peer streaming overlays: An application perspective

paper_content:

We compare two representative streaming systems using mesh-based and multiple tree-based overlay routing through deployments on the PlanetLab wide-area experimentation platform. To the best of our knowledge, this is the first study to compare streaming overlay architectures in real Internet settings, considering not only intuitive aspects such as scalability and performance under churn, but also less studied factors such as bandwidth and latency heterogeneity of overlay participants. Overall, our study indicates that mesh-based systems are superior for nodes with high bandwidth capabilities and low round trip times, while multi-tree based systems currently cope better with stringent real time deadlines under heterogeneous conditions.
---
paper_title: Gossiping in distributed systems

paper_content:

Gossip-based algorithms were first introduced for reliably disseminating data in large-scale distributed systems. However, their simplicity, robustness, and flexibility make them attractive for more than just pure data dissemination alone. In particular, gossiping has been applied to data aggregation, overlay maintenance, and resource allocation. Gossiping applications more or less fit the same framework, with often subtle differences in algorithmic details determining divergent emergent behavior. This divergence is often difficult to understand, as formal models have yet to be developed that can capture the full design space of gossiping solutions. In this paper, we present a brief introduction to the field of gossiping in distributed systems, by providing a simple framework and using that framework to describe solutions for various application domains.
---
paper_title: Self-stabilizing and Byzantine-Tolerant Overlay Network ⋆

paper_content:

Network overlays have been the subject of intensive research in recent years. The paper presents an overlay structure, S-Fireflies, that is self-stabilizing and is robust against permanent Byzantine faults. The overlay structure has a logarithmic diameter with high probability, which matches the diameter of less robust overlays. The overlay can withstand high churn without affecting the ability of active and correct members to disseminate their messages. The construction uses a randomized technique to choose the neighbors of each member, while limiting the ability of Byzantine members to affect the randomization or to disturb the construction. The basic ideas generalize the original Fireflies construction that withstands Byzantine failures but was not self-stabilizing.
---
paper_title: How robust are gossip-based communication protocols?

paper_content:

Gossip-based communication protocols are often touted as being robust. Not surprisingly, such a claim relies on assumptions under which gossip protocols are supposed to operate. In this paper, we discuss and in some cases expose some of these assumptions and discuss how sensitive the robustness of gossip is to these assumptions. This analysis gives rise to a collection of new research challenges.
---
paper_title: Real-Time, Byzantine-Tolerant Information Dissemination in Unreliable and Untrustworthy Distributed Systems

paper_content:

In unreliable and untrustworthy systems, information dissemination may suffer network failures and attacks from Byzantine nodes which are controlled by traitors or adversaries, and can perform destructive behaviors. Typically, Byzantine nodes together or individually "swallow" messages, or fake disseminated information. In this paper, we present an authentication-free, gossip-based real-time information dissemination mechanism called RT-LASIRC, in which "healthy" nodes utilize Byzantine features to defend against Byzantine attacks. We show that RT-LASIRC is robust against blackhole and message-faking attacks. Our experimental studies verify RT-LASIRC's effectiveness.
---
paper_title: BAR gossip

paper_content:

We present the first peer-to-peer data streaming application that guarantees predictable throughput and low latency in the BAR (Byzantine/Altruistic/Rational) model, in which non-altruistic nodes can behave in ways that are self-serving (rational) or arbitrarily malicious (Byzantine). At the core of our solution is a BAR-tolerant version of gossip, a well-known technique for scalable and reliable data dissemination. BAR Gossip relies on verifiable pseudo-random partner selection to eliminate non-determinism that can be used to game the system while maintaining the robustness and rapid convergence of traditional gossip. A novel fair enough exchange primitive entices cooperation among selfish nodes on short timescales, avoiding the need for long-term node reputations. Our initial experience provides evidence for BAR Gossip's robustness. Our BAR-tolerant streaming application provides over 99% convergence for broadcast updates when all clients are selfish but not colluding, and over 95% convergence when up to 40% of clients collude while the rest follow the protocol. BAR Gossip also performs well when the client population consists of both selfish and Byzantine nodes, achieving over 93% convergence even when 20% of the nodes are Byzantine.
---
paper_title: Understanding P2P-TV Systems Through Real Measurements

paper_content:

In this paper, we consider two popular peer-to-peer TV (P2P-TV) systems: PPLive, one of the today most widely used P2P-TV systems, and Joost, a promising new generation application of which no previous measurement study has been considered. Besides the traditional measurements like the amount of generated traffic for signaling and data transmission, the novel contribution of the paper consists in investigating the content distribution mechanisms. In particular, we evaluate the characteristics of both data distribution and signaling process for the overlay network discovery and maintenance. By considering two or more clients in the same sub-network, we observe the capability of the system to exploit the locality of peers. We also explore how the system adapts to different network conditions. The methodology we develop allows also to identify periodic behavior of the application, highlighting bursts of both data and signaling traffic.
---
paper_title: Detecting Malicious Peers in Overlay Multicast Streaming

paper_content:

Overlay multicast streaming is built out of loosely coupled end-hosts (peers) that contribute resources to stream media to other peers. Peers, however, can be malicious. They may intentionally wish to disrupt the multicast service or cause confusions to other peers. We propose two new schemes to detect malicious peers in overlay multicast streaming. These schemes compute a level of trust for each peer in the network. Peers with a trust value below a threshold are considered to be malicious. Results from our simulations indicate that the proposed schemes can detect malicious peers with medium to high accuracy, depending on cheating patterns and malicious peer percentages.
---

Title: Security and Privacy Issues in P2P Streaming Systems: A Survey

Section 1: Overview
Description 1: Provide a broad introduction to P2P streaming systems, their advantages, and associated security challenges.

Section 2: Examples
Description 2: Illustrate real-world examples of security attacks on P2P streaming systems to highlight the importance of addressing security issues.

Section 3: Security Considerations for P2P Streaming
Description 3: Discuss the specific security concerns that arise in P2P streaming systems, detailing the important aspects of securing such systems.

Section 4: Threat Model
Description 4: Define possible sources and targets of attacks in P2P streaming systems, outlining the main aspects of the threat landscape.

Section 5: System-level Security Goals in P2P Streaming
Description 5: Identify and describe the goals that a secure P2P streaming system must achieve to mitigate security threats.

Section 6: Data and Content Security Goals in P2P Streaming
Description 6: Discuss the security properties required to protect the integrity and confidentiality of data and content in P2P streaming.

Section 7: Protection Mechanisms
Description 7: Present mechanisms and strategies that can be employed to protect against security threats in P2P streaming systems.

Section 8: Common Attacks in P2P Streaming Systems
Description 8: Provide an overview of typical attacks targeting P2P streaming systems and the conditions under which these vulnerabilities are exploited.

Section 9: Security Practices
Description 9: Discuss existing security solutions in P2P streaming, their vulnerabilities, and how they can be improved to provide better protection.

Section 10: Tree-based Approaches
Description 10: Examine tree-based overlay topologies in P2P streaming and their associated security challenges and solutions.

Section 11: Mesh-based Approaches
Description 11: Investigate mesh-based overlay topologies, comparing their security strengths and weaknesses to other approaches.

Section 12: Gossiping and Byzantine Faults
Description 12: Analyze gossip protocols and their applicability in protecting against Byzantine faults in P2P streaming systems.

Section 13: Discussion
Description 13: Reflect on the trade-offs between security and performance in P2P streaming systems, and the balance required to maintain both effectively.

Section 14: Further Work
Description 14: Identify open issues and future research directions in the field of P2P streaming security.

Section 15: Conclusions
Description 15: Summarize the findings of the survey and provide final thoughts on the state and future of security and privacy in P2P streaming systems.