Basic principles and protocols Secure and resilient routing Resilient overlay networks Secure DNS PA197 Secure Network Design 3. Security Architectures I Eva Hladká, Luděk Matýska Faculty of Informatics March 6, 2024 Eva Hladká, Luděk Matýska PA197 Secure Network Design 3. Security Architectures I Basic principles and protocols Secure and resilient routing Resilient overlay networks Secure DNS Q Basic principles and protocols • Common Internet protocols and their resilience • Redundancy principle in network design Q Secure and resilient routing • Link and Path Protection Link Aggregation • Multipath routing Q Resilient overlay networks O Secure DNS Eva Hladká, Luděk Matýska PA197 Secure Network Design 3. Security Architectures I Basic principles and protocols Secure and resilient routing Common Internet protocols and their resilience Resilient overlay networks Redundancy principle in network design Secure DNS Networks rely on protocols o a communication protocol is a set of rules that define how data are exchanged between computers • A protocol defines • syntax • semantics • synchronization independent on the implementation o Protocol layering • basic design principle • allows decomposition Eva Hladká, Luděk Matýska PA197 Secure Network Design 3. Security Architectures I Basic principles and protocols Secure and resilient routing Resilient overlay networks Secure DNS ( I OSI Reference Model Common Internet protocols and their resilience Redundancy principle in network design Application program Application Presentation Session Transport Network Data Link Physical Application layer Presentation layer Session layer Transport layer Network layer Data Link layer Physical layer Application program -z- 4— Application Presentation Session Transport Network Data link Physical o pzrr □ ö pzrr □ Eva Hladká, Luděk Matýska PA197 Secure Network Design 3. Security Architectures I Basic principles and protocols Secure and resilient routing Resilient overlay networks Secure DNS Common Internet protocols and their resilience Redundancy principle in network design TCP Reference Model Application Transport Network Datalink Physical Physical transmission medium Eva Hladká, Luděk Matýska PA197 Secure Network Design 3. Security Architectures I Basic principles and protocols Secure and resilient routing Common Internet protocols and their resilience Resilient overlay networks Redundancy principle in network design Secure DNS • Communication between application programs • end-to-end • whole messages • split into packets at Internet layer • Transmission Control Protocol (TCP) • reliable transport • flow/congestion control • User Datagram Protocol (UDP) • unreliable transport • connection-less Eva Hladká, Luděk Matýska PA197 Secure Network Design 3. Security Architectures I Basic principles and protocols Secure and resilient routing Common Internet protocols and their resilience Resilient overlay networks Redundancy principle in network design Secure DNS 9 Provides reliable transport • byte-oriented stream • guarantees ordering • guarantees integrity • However, the guarantees not prone against active adversary • man-in-the-middle: easy to modify • source address • content • sequence prediction attack • injects counterfeit attacks Eva Hladká, Luděk Matýska PA197 Secure Network Design 3. Security Architectures I Basic principles and protocols Secure and resilient routing Common Internet protocols and their resilience Resilient overlay networks Redundancy principle in network design Secure DNS • Redundancy: an old engineering principle • do not create (remove) any single point of failure (SPOF) • failure in one component should not crash the system • A design principle to prevent a failure of the whole system • It comes with added cost and complexity • Cost implications • more components than actually needed to perform an operation • cost limits the extent of redundancy • i.e. how many components could fail before the system goes down 9 Complexity implications • adding components makes the system more complex • higher complexity increases the probability of a failure • RYF-principle (Robust Yet Fragile) o Redundancy is not a backup Eva Hladká, Luděk Matýska PA197 Secure Network Design 3. Security Architectures I Basic principles and protocols Secure and resilient routing Common Internet protocols and their resilience Resilient overlay networks Redundancy principle in network design Secure DNS • Needs to have multiple instance of everything that can possibly fail • links • ports • active elements Everything must be at least doubled (no SPOF) • The principle demonstration LAN A Connection LAN B Connection Standard LAN Connectior ■ EMM ■ 1 Red Box 1 M M 1 DAN DAN DAN DAN 1p 3AN ~ Switch Eva Hladká, Luděk Matýska PA197 Secure Network Design 3. Security Architectures I Basic principles and protocols Secure and resilient routing Resilient overlay networks Secure DNS Common Internet protocols and their resilience Redundancy principle in network design • Redundancy is a tool, availability is the goal • we would like to have always available systems • in practice, high availability is achievable • Redundancy contributes to availability keeping the system up in presence of failures o Reaction in case of failure: • failure detection • failing over • reconnection • Network protocols have different parts implemented o routing used as the next example Eva Hladká, Luděk Matýska PA197 Secure Network Design 3. Security Architectures I Basic principles and protocols Secure and resilient routing Resilient overlay networks Secure DNS Link and Path Protection Link Aggregation Multipath routing • A scheme to mitigate from network failure • link layer • end nodes of the link responsible for failover • Basic principles • failure recognition • selection of redundant path • Bi-directional Line Switched Ring (BLRS) • every link can carry payload and backup traffic at the time • four fiber • two fibers for working • two fibers for protection/backup • two-fiber • work and backup shared • half the capacity for backup Eva Hladká, Luděk Matýska PA197 Secure Network Design 3. Security Architectures I Basic principles and protocols Secure and resilient routing Resilient overlay networks Secure DNS Link and Path Protection Link Aggregation Multipath routing o Link aggregation • multiple links carry the traffics • failure of a single link reduces the overall throughput the redundancy principle in practice • Initially static configuration • high probability of configuration error • not able to properly detect the failure o Dynamic configuration • Link Aggregation Control Protocol (see next slides) Eva Hladká, Luděk Matýska PA197 Secure Network Design 3. Security Architectures I Basic principles and protocols Secure and resilient routing Resilient overlay networks Secure DNS Link and Path Protection Link Aggregation Multipath routing • Protect from network failure in connection oriented networks • Ring • Optical Mesh o MPLS (Multi Protocol Label Switching) • packet protection scheme • two link/node disjoint paths between ingress and outgress routers • outgress router compares packets • uses double the bandwidth • global path protection primary and backup label switched path (LSP) are computed and setup • the backup may not fulfill the SLA • backup LSP does not carry traffic • fault indication signal inform ingress router to switch to backup LSP Eva Hladká, Luděk Matýska PA197 Secure Network Design 3. Security Architectures I Basic principles and protocols Secure and resilient routing Resilient overlay networks Secure DNS Link and Path Protection Link Aggregation Multipath routing • Combining (aggregating) multiple network connections to • increase throughput • provide redundancy • The lowest three layers • layer 1: IEEE 1901 (power line) or IEEE 802.11 (wireless) • layer 2: across switch ports 9 layer 3: round robin scheduling • Provides load balancing and failover over the links • Link Aggregation Control Protocol (LACP) • IEEE 802.3ad standard to negotiate bundled links between switches • Packet reordering problem Eva Hladká, Luděk Matýska PA197 Secure Network Design 3. Security Architectures I Basic principles and protocols Secure and resilient routing Resilient overlay networks Secure DNS Link and Path Protection Link Aggregation Multipath routing ocols Vendor's protocols • CISCO: EtherChannel and Port Aggregation Protocol • Juniper: Aggregated Ethernet • Nortel, AVAYA: Multi-Link Trunking family of protocols • Huawei: Eth-Trunk Linux Bonding driver • bonds several NICs into a logical channel • can work in active or passive mode • fault tolerance (both) and load balancing (passive) Eva Hladká, Luděk Matýska PA197 Secure Network Design 3. Security Architectures I Basic principles and protocols Secure and resilient routing Resilient overlay networks Secure DNS Link and Path Protection Link Aggregation Multipath routing Benefits • fault tolerance • increased bandwidth • improved security Types of paths • overlapped • edge-disjoint • node-disjoint Problems with per-packet multipath routing • variable path MTU • variable latencies • packet reordering • debugging Equal-cost multipath routing (ECMO) • IEEE 8021Qbp (2014) Eva Hladká, Luděk Matýska PA197 Secure Network Design 3. Security Architectures I Basic principles and protocols Secure and resilient routing Resilient overlay networks Secure DNS Link and Path Protection Link Aggregation Multipath routing Eva Hladká, Luděk Matýska PA197 Secure Network Design 3. Security Architectures I Basic principles and protocols Secure and resilient routing Resilient overlay networks Secure DNS Link and Path Protection Link Aggregation Multipath routing • Optimized Link State Routing Protocol • RFC 3626 o IP routing for mobile ad hoc networks • Basic principles • limited flooding: 2-hop neighbor • multipoint relays (MPR) • only MPR can source topology control packets • limits the extent of knowledge shared among nodes • not all links are advertised • no reliable algorithm • a pro-active algorithms: route computed before used Eva Hladká, Luděk Matýska PA197 Secure Network Design 3. Security Architectures I Basic principles and protocols Secure and resilient routing Resilient overlay networks Secure DNS Link and Path Protection Link Aggregation Multipath routing • MANET a challenging environment for reliable routing • node mobility • limited battery capacity • low reliability of data transfer medium Reliable routing necessary for mobile ad hoc networks • Basic principles: • proactive routing • reactive routing Eva Hladká, Luděk Matýska PA197 Secure Network Design 3. Security Architectures I Basic principles and protocols Secure and resilient routing Resilient overlay networks Secure DNS Link and Path Protection Link Aggregation Multipath routing • Similar to routing in Internet o Example: Destination Sequence Distance Vector (DSDV) • periodic exchange of routing information • independent of actual payload transport • Drawbacks: • large number of control messages • high load on the network nodes • frequency must relate to the "mobility" of nodes within the network • can be very high or the routing info is obsolete • Not really suitable for MANET Eva Hladká, Luděk Matýska PA197 Secure Network Design 3. Security Architectures I Basic principles and protocols Secure and resilient routing Resilient overlay networks Secure DNS Link and Path Protection Link Aggregation Multipath routing • Reacts on data transfer needs • Route discovery and Route maintenance • responsibility to find a route lies with the source node—discovery • every node detects topology changes 9 Examples: • Dynamic Source Routing (DSR) • Ad-hoc On Demand Distance Vector Routing (AODV) 9 Flooding mechanisms to discover the route(s) • Naive approach: select the shortest path • suboptimal in MANET • creates congestion in the center of the network • "shortest" may not survive node mobility • Multipath routing proposed as a better alternative Eva Hladká, Luděk Matýska PA197 Secure Network Design 3. Security Architectures I Basic principles and protocols Secure and resilient routing Resilient overlay networks Secure DNS Link and Path Protection Link Aggregation Multipath routing • Several variants • delay aware protocols • reliable multipath protocols • minimum overhead • energy efficient • hybrid approaches • Follow: Mohammed Tariquea, Kemal E. Tepeb, Sasan Adibic, Shervin Erfanib: Survey of multipath routing protocols for mobile ad hoc networks. J. Network and Computer Applications, Vol. 32(6), pp 1125-1143, 2009 • http://www.sciencedirect.com/science/article/pii/ S1084804509001027 Eva Hladká, Luděk Matýska PA197 Secure Network Design 3. Security Architectures I Basic principles and protocols Secure and resilient routing Resilient overlay networks Secure DNS 9 Introduced by Andersen:2001 o An architecture to support e2e communication to • detect network outages and performance degradation o recover from these and do it fast (in terms of seconds even when used over the Internet) • An application layer overlay over the "standard" network • monitor the liveness and quality of Internet paths • take decision where to actually route each packet <* Optimizes application-specific routing metrics Eva Hladká, Luděk Matýska PA197 Secure Network Design 3. Security Architectures I Basic principles and protocols Secure and resilient routing Resilient overlay networks Secure DNS o Some problems with "standard" routing • routing metrics are not modifiable by users • interdomain routing usually not too sophisticated • quality measurements usually only intra-domain • RON concept • move routing to the end systems o but not to the applications • it is still a network • small scale (tens of RON nodes only) • independent end to end monitoring used for routing decisions • Sophisticated applications (e.g. videoconferencing), but also coordinated reaction to DOS attack • cooperative defense • RON nodes used for o detection near malicious data target • traffic control near source • coordinated response through RON nodes Eva Hladká, Luděk Matýska PA197 Secure Network Design 3. Security Architectures I Basic principles and protocols Secure and resilient routing Resilient overlay networks Secure DNS Associates host names with IP addresses Bidirectional 9 forward record: from host to IP address • reverse record: from IP address to host name Hierarchical distributed architecture • root servers • authoritative servers • data caching Specific vulnerabilities 9 Denial of service • information disclosure (reconnaissance before attack) • (authoritative) spoofing • cache poisoning Eva Hladká, Luděk Matýska PA197 Secure Network Design 3. Security Architectures I Basic principles and protocols Secure and resilient routing Resilient overlay networks Secure DNS růůt ii ii . CŮffl 1 .in-addr . ipS net org .CISCO too La WW isc gov ufi .ulc tx i imp .ttfdp* www jabber ftp Eva Hladká, Luděk Matýska PA197 Secure Network Design 3. Security Architectures I Basic principles and protocols Secure and resilient routing Resilient overlay networks Secure DNS • DNS security extension • uses PKI and digital signatures <* Server side authentication • signed zone information • storage for public keys • signed query answers (A, MX, PTR) o Client (resolver) side • origin authentication (authoritative) • data integrity • authoritative denial of existence Eva Hladká, Luděk Matýska PA197 Secure Network Design 3. Security Architectures I Basic principles and protocols Secure and resilient routing Resilient overlay networks Secure DNS Networks serving critical systems—the reliability of network as a whole becoming increasingly important • in some networks (e.g. MANET), the reliability is a necessary condition for proper operation Redundancy used as a standard engineering technique to achieve robustness • redundant systems more expensive o redundant systems more complex No "silver bullet" to solve the reliability requirement Presented examples of (more) reliable protocols • routing • resilient overlay networks Secure DNS as another example of the application of the basic principles Next lecture: Secure/Reliable data transport over the network Eva Hladká, Luděk Matýska PA197 Secure Network Design 3. Security Architectures I