Chapter 2: Fundamentals and Issues with Cooperation in Networking

1. Chapter 2: Fundamentals and Issues with Cooperation in Networking  Mohammad S. Obaidat, Fellow of the IEEE and Fellow of the SCS and Tarik Guelzim, Department of Computer Science and Software Engineering Monmouth University W. Long Branch, NJ 07764, USA

2. Introduction • In the recent years, wireless point-to-point networks such as ad hoc network, sensor networks and mesh networks have received a considerable amount of research attention due to their increased applications in both military and civilian applications. • A concrete military application would be for example a network composed of officers and soldiers that need to share common information, one implementation that takes into consideration the battery power of the mobile units is to centralize the data in the officers and to authorize access to the soldiers

3. Introduction • Research in this field has concentrated on improving cooperative caching in which systems exchange cache data to be reused by all systems in the network thus increasing the overall performance and reducing latency. • Cooperation is also improving handover in 3G system architectures given the differences between technologies and mobility principles in 3GPP and non 3GPP networks.

4. Introduction • This allowed to slowly introducing technology in the market while aiming at making it interoperable later when the technology matures. • Cooperative information architecture applies also to security in which many networks cooperate to assure the security of a system. • These systems operate in a geographically widely distributed environment with the goal to manage access to security among stakeholders.

5. Fundamentals of cooperating networks • 4G networks can be defined as composite networks made of heterogeneous wireless networks. These networks include but not limited to: • Broadcast networks. • Wireless wide area networks (Cellular). • Wireless metropolitan networks (WiMAX). • Short range networks (WLAN, PAN, RFID, …)

6. Fundamentals of cooperating networks • Convergence between networks, terminals and services will be the main characteristic in 4G networks for both local and wide area setups. With this in mind, cooperation and cognition will become dominant features in the future of wireless networks.

7. Fundamentals of cooperating networks • Cooperative communication is a mean to enhance the network performance through spatial diversity. Cooperative transmission can be useful for users with single antennas and where there are no dedicated relays. The changing topology and non-centralized nature of cooperative communication is particularly useful for MANET. • Relay channel is the basic building block. • Unlike relay channels, in a user-cooperative model each of the cooperating users has data to transmit.

8. Fundamentals of cooperating networks:Cooperative Adhoc Network Services • Some studies have shown that sharing cache data between nodes can improves significantly the performance in P2P networks. • A novel technique relies on two ideas: • The cache data requests are transmitted to the cache layers on every node. • The cache data replies are only transmitted to the cache layer at the intermediate nodes that need to cache the data

9. Fundamentals of cooperating networks:Cooperative Adhoc Network Services • The implementation consists of: • A cooperative cache agent (CCA): This is a module that maps application protocol messages to the corresponding cooperative cache layer messages. • A cooperative cache daemon (CCD): This is a component that implements different cooperative cache mechanisms. • A cooperative cache supporting library (CCSL): this is the core component to provide primitive operations of the cooperative cache such as checking packets, recording data access history and cache read and writes primitives.

10. Fundamentals of cooperating networks:Cooperative Quality of Service (CQoS) • Mobile ad hoc networks allow fast and temporary connections among mobile nodes without the help of any infrastructure. • Quality of Service routing algorithms have been subject to a lot of research in the recent years. Ore Extraction Distributed ad hoc Routing (CEDAR) algorithm or the Ticket Based Probing (TBP) and many others like QoS routing based on bandwidth. • A new breed of protocols that remedy the current drawbacks are the multi-rate aware routing protocols that allow to provide a higher throughput and lower the delay by using the smallest path between hops. • The way this works is that while the distance of one hop decreases, transmitting at a higher bandwidth is most likely to be the chosen option since the required timeslots is reduced. On one hand we transmit the data quickly to the requesting node while we preserve the timeslots needed to transmit more data to other requesting nodes.

11. Fundamentals of cooperating networks:Cooperative data integrity insurance in Grid networks • Data integrity has become one of the central concerns of large scale projects of distributed computing systems. In order for the grid to be successful, the users of that grid must trust the results coming out of the grid computation. • One such model is the reputation system. There are three types of reputation systems: • A positive reputation system (PRS): This system rewards good behavior in order to encourage a desired outcome. • A negative reputation system (NRS): in contrast to PRS, this model punishes undesirable behavior. • A hybrid reputation system (HRS): in this model, both PRS and NRS are accorded points with different weights.

12. Fundamentals of cooperating networks:Cooperative data integrity insurance in Grid networks • The HRS is the default choice of many reputation systems since it gives the fluctuation of the nodes reputation in both directions. One concrete example is E-Bay for example. This balanced system has buyers and sellers affecting each other’s reputations by giving a feedback on the interaction experience. • THE TRUSTWORTHINESS OF A NODE IN GRID ARCHITECTURE IS DETERMINED BY THE SPEED, THE ACCURACY, THE AVAILABILITY AND THE CONSISTENCY.

13. Fundamentals of cooperating networks:Cooperative Intrusion Trace back and Response Architecture (CITRA) • CITRA was originally developed, with funding from the DARPA initiative, as an infrastructure for integrating intrusion detection systems with firewalls and routers. • CITRA was developed to help automate intrusion detection and analysis that are usually performed by human administrators. • This is critical for 2 reasons: • Analysis of intrusions manually can take hours or longer. The cost of resolving the issue rapidly mounts. • The analysis is a complex task that requires expert administrators and professionals in certain cases. This is not usually available to most companies.

14. Fundamentals of cooperating networks:Cooperative Intrusion Trace back and Response Architecture (CITRA) • CITRA uses two levels of organizations. • The first is CITRA communities and administrative domain that is controlled by management components named Discovery Coordinator (DC). • Second, communities are interconnected with adjacent devices i.e. no third CITRA node is placed between any two nodes. Trace back of intrusion events is done by auditing traffic at the registered devices within the CITRA network. • This mechanism is so advanced that it is able to track the malicious source packets. Detection is done as follows: • The detector send a trace back message to each CITRA neighbor • Each boundary Controller (BC) and host along the potential path of an attack uses the network audit trail (AT) to determine if the packets associated with the attack passed through the BC node. If this condition holds, the trace back message is sent to the neighbor node • This loop continues until reaching the source of an attack or an edge of the CITRA system.

15. Fundamentals of cooperating networks:Cooperative Sensor Networks • Research in wireless sensor network (WSN) has grown at a very large pace in the recent years especially in the field of security. • Because of the inherent architecture of WSN, they have been prone to a lot of passive attacks such as stealing, physical damage or active attacks where a group of hackers try to actively exploit certain implantation flaws that are in inherent within the system itself. • In wireless sensor networks, it is primordial that a monitoring system be put in place to detect, diagnose and protect attacks on the system. This is no easy task mainly because of two variables: the first is the environment the networks are deployed to operate in and second because of the technical specifications of the wireless sensors themselves that have many restrictions in terms of power consumption, memory requirements and CPUs.

16. Fundamentals of cooperating networks:Cooperative Sensor Networks • WSN are the technology of the future. They are broadly used in a number of crucial and critical applications such as monitoring of seismic activities, performance analysis of manufacturing process and performance analysis, studies of wild life and detection as well as prevention in wild fires. • One of the most relevant uses is military application, in which a network of these devices is put on place to track enemy movements as well as for spying purposes. • Upon deployment, senor nodes use algorithms to self organize into a mesh of wireless networks and thus be able to collaborate together to extract information and process it together. • Each node uses automatic discovery of surrounding nodes using peer-to-peer networking. Usually these are variations of muti hop and cluster based routing algorithms, which is essence apply technique to dynamically discover resource within that network.

17. Fundamentals of cooperating networks: Cooperative Relaying Network Service • Cooperative communications and networking provides new paradigms of distributed processing and transmission. • This gives new capabilities in terms of capacity and diversity gain in wireless networks. For instance, infrastructure networks, 3G networks and wireless sensor networks improve in terms of performance of both area coverage and quality of service (QoS). • It also enables a distributed time-space signal processing that can be used in monitoring, localization, distributed measurement, fail over transparency, reduced network complexity and reduced energy consumption per node.

18. Fundamentals of cooperating networks: Delay Optimization in Cooperative Relaying • To achieve greater coverage and capacity, relaying has been widely suggested to be used in future generation of wireless networks. There are two kinds of relaying techniques in use today. The first is relaying of the signal once after amplification and the second is relaying the signal after decoding.

19. Fundamentals of cooperating networks: Delay Optimization in Cooperative Relaying • Relying stations can be mobile or stationary. By introducing random cyclic delays at the relay stations along with channel state information about the mobile unit, the best performance is given by the network. • However, this technique comes at the expense of network overhead. To optimize this technique, the best segment of the signal is picked from each relay and taken into account to create the full signal, thus, only a fractional feedback is required. In addition, this technique lowers the system complexity and gives high spectrum efficiency.

20. Fundamentals of cooperating networks:Distributed Cooperative automatic redistribution request (ARQ) Scheme in Wireless Networks • The ARQ scheme is made available through the persistent relay carrier sensing multiple access protocol (PRCSMA) and is a novel scheme that allows the execution of a distributed cooperative automatic retransmission request in IEEE 802.11 wireless networks. • The underlying idea of this protocol is to enhance the performance of the WLAN MAC layer and to extend its coverage. • ARQ works as follows: once a destination station receives a erroneous packet, it requests its retransmission from any of the relays that “overheard” the transmission at the first place. Space and time diversity can be used to select the “best” candidate among the relays that will retransmit the requested packet. With such a scheme, we can improve channel usage and extend the coverage and retransmission of data.

21. Fundamentals of cooperating networks:Resource Sharing via Planed Relay for HWN • Multi-hop relaying is one way to employ multiple relays to serve a communication channel. • It first appeared in the 1940’s with an application focused on extending transmission range. • Nowadays, it is used to increase network throughput and improve network reliability. • In a cooperative relaying model, partnership can take different forms (e.g. multi-hop relaying) with different degrees of complexity.

22. Fundamentals of cooperating networks:Resource Sharing via Planed Relay for HWN • In theory, when compared to regular cellular network, relays provide the capability to substitute poor single hop quality of the wireless medium and better link quality between towers. It also allows a higher end to end data rate by allowing two simultaneously communicating interfaces.

23. Fundamentals of cooperating networks:Resource Sharing via Planed Relay for HWN • The following scheme has been shown to extend service rang, optimize cell capacity and minimize transmission power. It has also allowed to cover “shadow” areas and support load balancing between networks.

24. ISSUES AND SECURITY FLAWS WITH COOPERATING NETWORKS: WIRELESS SENSOR NETWORKS CASE STUDY • Cooperation has its benefits but sure has its flaws. Since cooperative networking is still in its infancy stage, the issues that are reported are only experimental ones. • In order to bring understand some real life security issues in cooperation, we detail in the following sections issues with a dominant cooperative network type: Wireless sensor networks (WSN).

25. WIRELESS SENSOR NETWORKS CASE STUDY: General Issues and Contingencies • As in any wireless computer network, enhancing operation and access security starts by defining goals as to what security encompass. The following are the security goals of most forms of cooperative networks: • Integrity: there must be a mechanism by which we need to tell whether a message received has been altered by an unauthorized node. • Authentication: this is the most basic form of security in which we need to determine the identity of the source of the information as well as the reliability of the sender node. • Confidentiality: This also an important security metric through which message are encrypted using an encryption algorithm to keep the communication among the sensor network private and eavesdrop resistant. • Availability: as in any computer network, having “healthy” nodes provides and ensures the normal flow of the data across the network without interruption.

26. WIRELESS SENSOR NETWORKS CASE STUDY: General Issues and Contingencies • The major problems in these networks can be summarized into four categories. • Hackers and malicious users often use one of them or a combination of two or more when targeting weak nodes. • The first to mention is the interruption technique: In this kind of attack, the hacker cuts off the communication link in the sensor network and thus rendering the node unavailable. • Usually this can be accomplished using methods such as code injection in which additional code is added maliciously to the device to be able to accomplish operations of interest to the hacker.

27. WIRELESS SENSOR NETWORKS CASE STUDY: General Issues and Contingencies • The second mechanism that threatens the wireless network is the interception technique in which the hacker compromises the sensor network by capturing data and after analysis using its content to gain unauthorized access to the entire network an example of such an attack is the node capture attack. • The third method of gaining unauthorized access to the WSN is through modification of transmitted packets by tempering with their content. This might lead to problem such as Denial of Service attack and network flooding in which a large amount of unsupported data is consuming the network bandwidth. • The fourth type of attack is the fabrication attack. In this latter, the malicious user inserts false information and data into the network and thus forces the rest of the sensor node to think that the network cannot be trusted anymore i.e. compromised.

28. WIRELESS SENSOR NETWORKS CASE STUDY: General Issues and Contingencies • Information gathering: In WSN, this is a type of passive attack that is usually implemented by a hacker who proves to have very powerful resources that enable him to extract and collect information on the fly and mine it for useful data that can allow access to the network such as keys, paraphrases and so on. • Node insurrection: In this kind of attack the malicious user leads a cracking attack on the entire network that leads to obtaining encryption keys as well as other cryptographic data and thus compromising the whole sensor network.

29. WIRELESS SENSOR NETWORKS CASE STUDY: General Issues and Contingencies • Sensor node injection: In this type of attack the hacker injects a similar node to the network and lure peer nodes that it is legitimate. Hence, attack suck as packet forwarding and data analysis can be implemented. Although this sounds like an easy attack to conduct, however, it is very hard in certain setups win which the network is physically secured (military installation for example). • Traffic mining: This is another attack in which the attacker employs tools to analyze the traffic between the nodes as well as extract information in terms of key, encryptions used and so on. This occurs in the early stage of conducting a successful attack of a sensor network.

30. WIRELESS SENSOR NETWORKS CASE STUDY: General Issues and Contingencies • Routing Information Spoofing: Spoofing routing information is a very widely used attack against wireless sensor networks. To intrude such a network, the attacker manipulates the routing tables either in software by injecting loop records in the lead nodes, or hardware based, by positioning devices that are able to attract or repel network traffic. • Selective Filtering: For this attack to be implemented, an attacker must first hijack a sensor node, either physically or remotely. After a successful compromise of the node, this latter is altered to control the information that is to be sent or forwarded.

31. Conclusions • Cooperative communication offers an alternative method to leverage existing network infrastructure by means of spatial diversity. • Cooperation helps users to get the most from available resources. The philosophy of user cooperation is based on the theory of the relay channel. • We have discussed the fundamentals of cooperative networks and the services that it presents. We scratched the surface on some services that have been experimented and are in use today such as CQoS and cooperative data caching. These two play an important role in enhancing both network throughput and capacity as well as availability.

32. Conclusions • Cooperation today is focused on layers 1, 2 and 3 of the OSI model allowing existing application (layer 6 and 7) to benefit from it transparently or with minimal change. • On the other hand, there are some security issues with cooperation that are inherent from wireless ad hoc networks. Some flaws that attackers can use to either provoke a DoS on the network or to leverage the capacity of their nodes at the detriment of others but hogging cooperative resources or launching WAN level attacks.