Peer2peer Network Service Discovery for Ad-hoc Networks 11.12.2003 - - PowerPoint PPT Presentation

▶

Nov 13, 2023 39 likes •361 views

Hauptseminar im Wintersemester 2003 / 2004 Ad-hoc networking: concepts, applications, and security Peer2peer Network Service Discovery for Ad-hoc Networks 11.12.2003 Michael Dyrna dyrna@in.tum.de Outline I. Introduction II. Design of

SLIDE 1

Peer2peer Network Service Discovery for Ad-hoc Networks

Hauptseminar im Wintersemester 2003 / 2004

Ad-hoc networking: concepts, applications, and security

11.12.2003 Michael Dyrna dyrna@in.tum.de

SLIDE 2

Outline

Peer2peer Network Service Discovery for Ad-hoc Networks · Michael Dyrna · 2

I. Introduction II. Design of Service Discovery Protocols

III. Mechanisms and Techniques
IV. Existing Service Discovery Protocols

V. Security Aspects

VI. Summary & Outlook

SLIDE 3

Outline

I. Introduction II. Design of Service Discovery Protocols

III. Mechanisms and Techniques
IV. Existing Service Discovery Protocols

V. Security Aspects

VI. Summary & Outlook

Peer2peer Network Service Discovery for Ad-hoc Networks · Michael Dyrna · 3

SLIDE 4

Traditional service management

traditional system administration not complex but time-consuming addresses must be assigned and published no standardised representation failures not handled drivers necessary on every client nomadic users?

Peer2peer Network Service Discovery for Ad-hoc Networks · Michael Dyrna · 4

SLIDE 5

Background

proliferation of mobile networks modularity is new goal of system development peer-to-peer succeeds client/server problem: service management service discovery necessary

Peer2peer Network Service Discovery for Ad-hoc Networks · Michael Dyrna · 5

SLIDE 6

Goals of Service Discovery

enable modularity therefore: services advertise themselves clients search for services

I am a colour laser printer with 600 dpi resolution. I can print 12 pages per minute. I am looking for a printer with at least 300 dpi. Peer2peer Network Service Discovery for Ad-hoc Networks · Michael Dyrna · 6

SLIDE 7

Scenario: Mobile phone, PDA and head phone

SMS dial-up Internet connection audio input / output video input (camera) video output storage audio in-/output audio input audio output

use / provide services use / provide services use / provide services Peer2peer Network Service Discovery for Ad-hoc Networks · Michael Dyrna · 7

SLIDE 8

Outline

I. Introduction II. Design of Service Discovery Protocols

III. Mechanisms and Techniques
IV. Existing Service Discovery Protocols

V. Security Aspects

VI. Summary & Outlook

Peer2peer Network Service Discovery for Ad-hoc Networks · Michael Dyrna · 8

SLIDE 9

Properties

enable software components to find each other on a network provide a means for describing a service (for matching) techniques to detect changes in component availability maintain a consistent view of components

Peer2peer Network Service Discovery for Ad-hoc Networks · Michael Dyrna · 9

SLIDE 10

Entities (1)

Service User Service Manager

service request (multicast) service reply (unicast)

(a) without service cache manager SM holds information about services, attributes, interfaces SU queries for service and selects most appropriate one

Peer2peer Network Service Discovery for Ad-hoc Networks · Michael Dyrna · 10

SLIDE 11

Entities (2)

Service User Service Manager Service Cache Manager (b) with service cache manager

service registration (unicast) service ACK (unicast) service request (unicast) service reply (unicast)

(acts as broker)

Peer2peer Network Service Discovery for Ad-hoc Networks · Michael Dyrna · 11

multicast only for discovery of SCMs!

SLIDE 12

Discovery

SU or SCM SU or SCM SCM or SM SCM or SM

aggressiv e lazy directed

probe reply reply advertise probe reply

Peer2peer Network Service Discovery for Ad-hoc Networks · Michael Dyrna · 12

SLIDE 13

Registration

service managers register their service descriptions with all discovered service cache managers service users can subscribe notification about changes in service descriptions of interest consistency is maintained by lease time (= period that limits validity of registration and subscription)

Peer2peer Network Service Discovery for Ad-hoc Networks · Michael Dyrna · 13

SLIDE 14

Data Representation

service identity (unique and location dependant, mandatory) service type (mandatory)

ptional: attributes
ptional: user interface
ptional: programme interface

Identity 192.168.8.15/mpool15 Type modem Attributes baud=28800 phonenumbersallowed=national dialprefix=’0’

Example:

Peer2peer Network Service Discovery for Ad-hoc Networks · Michael Dyrna · 14

SLIDE 15

Outline

I. Introduction II. Design of Service Discovery Protocols

III. Mechanisms and Techniques
IV. Existing Service Discovery Protocols

V. Security Aspects

VI. Summary & Outlook

Peer2peer Network Service Discovery for Ad-hoc Networks · Michael Dyrna · 15

SLIDE 16

Consistency Maintenance

changes in topology on purpose or due to failure polling: service user queries service manager or service cache manager to obtain up-to-date information notification: service user registers with service manager to

btain up-to-date information

service manager notifies registered service users about changes analogue: service manager <> cache manager

Peer2peer Network Service Discovery for Ad-hoc Networks · Michael Dyrna · 16

SLIDE 17

Failure Detection & Recovery

soft state persistence: components send „heart beat messages“ regularly no reception => assume remote component failed next reception => recovery & update application level persistence bounded retries: retry several times and throw exception in case of exception, application can: ignore it (good for polls/notifications) retry operation (assume failure until success) discard knowledge about component

Peer2peer Network Service Discovery for Ad-hoc Networks · Michael Dyrna · 17

SLIDE 18

Outline

I. Introduction II. Design of Service Discovery Protocols

III. Mechanisms and Techniques
IV. Existing Service Discovery Protocols

V. Security Aspects

VI. Summary & Outlook

Peer2peer Network Service Discovery for Ad-hoc Networks · Michael Dyrna · 18

SLIDE 19

Service Location Protocol, Version 2 (SLP2)

developed by IETF SrvLoc group (Sun, HP, Novell, IBM, ...) vendor and platform independent requires TCP/IP (uses mostly UDP) messages binary + string-based User Agents, Service Agents, Directory Agents (optional) DA address from DHCP or statically configured or by discovery URL: type://host:port/path protocol for using service is independent from SLP service templates by IANA scopes for administrative grouping

Peer2peer Network Service Discovery for Ad-hoc Networks · Michael Dyrna · 19

SLIDE 20

Jini

extension of Java developed by Sun, AOL + mobile equipment vendors for inter-connecting Java-enabled devices any component is service user and manager everything modelled as classes and objects Lookup Table can be on Lookup Server (optional) methods: store, match, fetch mobile code (Lookup Table contains RMI interface) “discovery and join” groups for administrative grouping

Peer2peer Network Service Discovery for Ad-hoc Networks · Michael Dyrna · 20

SLIDE 21

Salutation

developed by IBM, HP, Sun, Cisco, ... platform and network independence (any transport layer) can also handle access to services Salutation Manager (mandatory) service broker handles communication (via Transport Manager) queries other Managers for services services register with only one Salutation Manager Functional Units = defined classes of devices and services Service Session Management: Salutation Mode, Emulated Mode, Native Mode

Peer2peer Network Service Discovery for Ad-hoc Networks · Michael Dyrna · 21

SLIDE 22

Universal Plug and Play (UPnP)

developed by Microsoft, Intel, Compaq, Cisco, ... implemented in Windows XP extension of Windows Plug&Play requires TCP/IP uses HTTP-over-UDP, SOAP, XML Control Point, (controlled) device

nly 2-party-architecture

no consistency maintenance control, eventing, presentation

Peer2peer Network Service Discovery for Ad-hoc Networks · Michael Dyrna · 22

SLIDE 23

Bluetooth Service Discovery Protocol (SDP)

Bluetooth = short-range communication system describes all network layers, one of which is SDP developed by Microsoft, Intel, mobile equipment vendors pico nets with limited number of devices can overlap SDP server and client in every device no service cache manager search or browse consistency maintenance delegated to lower layers Service Records consist of Service Attributes

Peer2peer Network Service Discovery for Ad-hoc Networks · Michael Dyrna · 23

SLIDE 24

Comparison

Peer2peer Network Service Discovery for Ad-hoc Networks · Michael Dyrna · 24

SLP2 Jini Salutation UPnP Bluetooth SDP (main) developer IETF Sun Salutation Consortium Microsoft Microsoft + Intel network transport TCP/IP independent independent TCP/IP Bluetooth programming language independent Java independent independent independent OS and platform dependent independent independent dependent independent attributes searchable yes yes yes no yes service cache manager

ptional
ptional

mandatory no no scoping scopes groups no no not necessary characteristics very lightweight code mobility, Java integration network independence, service access focus on hardware high integration qualification for ad- hoc

integration

scalability + + +

SLIDE 25

Outline

I. Introduction II. Design of Service Discovery Protocols

III. Mechanisms and Techniques
IV. Existing Service Discovery Protocols

V. Security Aspects

VI. Summary & Outlook

Peer2peer Network Service Discovery for Ad-hoc Networks · Michael Dyrna · 25

SLIDE 26

Threats

perturbation of discovery denial-of-service flooding with nonsense-services register and de-register services without permission unauthorised use of services causes cost and / or enables access to sensitive data man-in-the-middle attack eavesdrop sensitive service content (e.g. print service) forward service data to actual service manager to disguise

Peer2peer Network Service Discovery for Ad-hoc Networks · Michael Dyrna · 26

SLIDE 27

Requirements

Peer2peer Network Service Discovery for Ad-hoc Networks · Michael Dyrna · 27

availability authenticity access control integrity non-repudiation confidentiality DoS flooding

unauth. commands
unauth. use

man-in-the-middle

not specific

SLIDE 28

Mechanisms

Peer2peer Network Service Discovery for Ad-hoc Networks · Michael Dyrna · 28

availability access control authenticity integrity non-repudiation confidentiality limit service registrations rely on network layer maintain access control lists rely on network access control generic mechanisms (asymmetric cryptography) problem: secure key distribution

SLIDE 29

Reality

Peer2peer Network Service Discovery for Ad-hoc Networks · Michael Dyrna · 29

SLP2: optional authentication feature but not for service users manual key distribution Jini: Java provides most mechanisms, but mobile code causes new challenges: server authentication and authorisation trust problem client -> proxy (what does the proxy do?) integrity only for messages, not for objects so far Salutation: optional authentication (username / password) UPnP: “Security considerations: to be determined” Bluetooth: usage protection and information confidentiality SDP relies on these mechanisms

SLIDE 30

Outline

I. Introduction II. Design of Service Discovery Protocols

III. Mechanisms and Techniques
IV. Existing Service Discovery Protocols

V. Security Aspects

VI. Summary & Outlook

Peer2peer Network Service Discovery for Ad-hoc Networks · Michael Dyrna · 30

SLIDE 31

Summary & Outlook

trend to dynamic networks (like ad-hoc) => peer-to-peer approaches & service discovery necessary service discovery allows modularity consistency maintenance & failure handling important challenges SLP2 + Jini for large, Bluetooth for small homogeneous, Salutation for heterogeneous ad-hoc networks, UPnP at most for Windows notebooks ;-) co-existence + more protocols? security issue not well solved => future improvements?

Peer2peer Network Service Discovery for Ad-hoc Networks · Michael Dyrna · 31

SLIDE 32

Thank you for your attention! :-)

Questions? Answers!

Peer2peer Network Service Discovery for Ad-hoc Networks · Michael Dyrna · 32