Ad Hoc & Sensor Networks Advanced Topics in Computer Networks Introduction Ad Hoc & Sensor Networks Ad Hoc Networks Sensor Networks Security Concerns 1
Introduction Introduction Definitions (ad hoc?) Ad Hoc Networks Characteristics Motivation & Applications Ad Hoc Networks History Ad Hoc Networks Security Concerns Ad Hoc Introduction definition concerned with a particular end or purpose; formed or used for specific or immediate problems or needs (Merriam-Webster s Collegiate Dictionary) Wireless Ad Hoc Networks definition mobile platforms or nodes that can move freely and establish ephemera wireless networks without any aid from central entities (e.g. access points) 2
Ad Hoc Characteristics Ad Hoc Nodes need to be fully functional in: routing capabilities (in multi-hop ad hoc networks) security (ad hoc networks have no borders to be defended) Dynamic Topology mobile nodes current Internet routing protocols are not suitable for ad hoc networks Ad Hoc Characteristics Unstable Data Links wireless links high medium error rates consequences in the upper layer protocols TCP performance in wireless environments Limited Battery Resources limited processing power and limited bandwidth 3
Ad Hoc Applications Impossibility to deploy a wired network historical buildings Lack of infrastructure destruction of previous infrastructure; or temporary need only (e.g. press rooms in conference centers) Military Applications Ad Hoc Applications distributed network - no single point of failure no need of previous or intact infrastructure Wireless Ad Hoc Nets Go to War http://www.sensorsmag.com/articles/0504/10/main.shtml 4
Ubiquitous Computing Ad Hoc Applications computational environments information anytime, anywhere offered through invisible interfaces data synchronization among devices Personal Area Networks (PANs) short-range network of interconnected devices PAN Technologies IEEE 802.15 WG IEEE 802.15.1 - Bluetooth based IEEE 802.15.3 - Ultra Wide Band (UWB) IEEE 802.15.4 - ZigBee (Ubiquitous Computing) Past Implementations (non ad hoc!) The English NCR Microwave Bank - 1998 www.wired.com/news/technology/0,1282,14949,00.html The Swedish Electrolux Screen Fridge - 1999 www.electrolux.se/screenfridge/ 5
Sensor Networks coordinated sensors Ad Hoc Applications environmental & traffic control surveillance embedded sensors automotive airplanes etc. we will see more about sensor networks later... IETF MANET WG Ad Hoc Networks Today Goal standardize IP routing protocol functionality suitable for wireless routing application within both static and dynamic topologies. http://www.ietf.org/html.charters/manet-charter.html http://tonnant.itd.nrl.navy.mil/manet/manet_home.html IETF MANET WG Achievements (Aug. 2004) 1 informational RFC (RFC 2501); 3 experimental RFCs regarding ad hoc routing (RFC 2561, 3626, 3684); 1 internet draft also regarding ad hoc routing (DSR). 6
Introduction Ad Hoc Networks Ad Hoc Networks Basic Organization Ad Hoc Routing IETF Experimental RFC: AODV, OLSR and TBRF IETF Draft: DSR Sensor Networks Security Concerns Ad Hoc Networks Organization Flat or Zero-tier organization no hierarchy equivalent nodes 7
Ad Hoc Networks Organization Hierarchical clustered network ad hoc nodes with different capablities & tasks Routing in Ad Hoc Networks Some assumptions on Internet routing today the network topology is - usually - well-known distance vector protocols (e.g. RIP, IGRP) link state protocols (e.g. OSPF) network links are - usually - stable low BER: [10-6,10-8 ] to copper and [10-10,10-15 ] to fiber optics LAN LAN WAN LAN LAN LAN 8
Routing in Ad Hoc Networks However, in mobile ad hoc networks network topology is - usually - unpredictable! network links are highly unstable high BER: [10-4,10-6 ] but 10-3 in some extreme cases. to remember error rate impact on upper protocols! Routing in Ad Hoc Networks IETF MANET WG desirable qualitative properties*: distributed operation (essential) loop-freedom demand-based operation and/or proactive operation routing security prevent disruption or modification of protocol operation sleep period operation unidirectional link support *according to RFC 2501 9
Routing in Ad Hoc Networks Ad Hoc Routing Protocols Taxonomy On-demand reactive protocols AODV (RFC 3561) - Jul. 2003 DSR (IETF Draft) - Jul. 2004 Table-driven pro-active protocols OLSR (RFC 3626) - Oct. 2003 TBRF (RFC 3684) - Feb. 2004 Hybrid Protocols no hybrid protocols at this moment... (Location-based protocols - geographical information ) Introduction Ad Hoc Networks Sensor Networks Characteristics Routing Security Concerns Ad Hoc Networks 10
Sensor Networks - Characteristics Sensor Networks Characteristics: very large number of mobile nodes (ideally!) large geographical areas (e.g. rain forests, volcanoes, etc.) multi-hop wireless networks none or very slow node mobility battery-resources define node lifetime (!!!) nodes are usually not supposed to be recovered nodes have a very low cost! not true!!! (at least nowadays) ~US$100,00 (each node today) Node Implementations UC Berkeley Manufacturing Institute bandwidth: 10kbps range: 3m to 30m serial data acquisition serial acquisition/transmission running TinyOS Rene Mote two Mote generations already Rene Mote Dot Mote Dot Mote see more in: http://kingkong.me.berkeley.edu/~nota/runningman/mote.htm 11
Sensor Networks - Topology General Topology sensor nodes information flow information flow sensor network sinks Sensor Networks - Routing Routing in Sensor Networks new routing concerns regarding battery consumption taxonomy of routing protocols for sensor networks hierarchical routing protocols LEACH, LEACH-C, etc. flat routing protocols SPIN, Direct Diffusion, etc. routing protocols for sensor networks are not standardized (yet!) 12
Introduction Ad Hoc Networks Sensor Networks Security Concerns Ad Hoc Networks Security Concerns Why security is so special in ad hoc networks? 13
Security Concerns How is traditional network security achieved today? guaranteed presence of some devices and services; Firewalls, IDS existence of a central services; Certification Authorities limited number of access points to the network; Routers, WLAN access points well-known and permanent infrastructure. AP network entry points (borders) Security Concerns However, in ad hoc networks... entities can join and leave the network at anytime; no central control entity exist; ad hoc network have no defined borders; no permanent infrastructure exist. network entry points 14
Security Concerns Security in Ad Hoc Networks is a Work-in-Progress... seminal proposals: 1999 Cambridge - Resurrecting Duckling Architecture 1999 Cornell - Threshold Cryptography Proposal some security issues in ad hoc networks secure routing, key exchange, distribution & management, intrusion detection systems, etc. however, not enough time to talk more about security (sorry!) leonardo.martucci@kau.se 15