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Protocoles et services internet Sommaire (prévision): q Introduction et rappels réseau q Rappels java Protocoles et services internet Sommaire (prévision): q Introduction et rappels réseau q Rappels java v Quelques compléments java q Protocoles: couche application v v v Html-http ftp smtp dns Réseaux Pair à pair H. Fauconnier q Sécurité, v sockets ssl q Serveurs web v Apache, servlet, web services q Wireless 3 séances de TP + examen M 2 -Internet 1 -1

Bibliographie q Java Network Programming, 3 rd Edition Elliotte Rusty Harold O'Reilly Media, Inc. Bibliographie q Java Network Programming, 3 rd Edition Elliotte Rusty Harold O'Reilly Media, Inc. . q Computer networking J. F. Kurose K. W. Ross Addison Wesley. H. Fauconnier M 2 -Internet 1 -2

Chapitre 1 q Introduction (rappels réseau) v Hôtes, réseaux d’accès, liens physiques v Commutation Chapitre 1 q Introduction (rappels réseau) v Hôtes, réseaux d’accès, liens physiques v Commutation par circuits, par paquets, structure du réseau v Pertes et délais v Protocoles et modèle en couches v Sécurité v Historique… H. Fauconnier M 2 -Internet 1 -3

Les composants… PC q millions of connected computing devices: hosts = end systems wireless Les composants… PC q millions of connected computing devices: hosts = end systems wireless laptop v running network cellular handheld apps q communication links v fiber, copper, access points radio, satellite wired links v transmission rate = bandwidth q routers: forward router packets (chunks of data) Mobile network server H. Fauconnier Global ISP Home network Regional ISP Institutional network M 2 -Internet Introduction 1 -4

Internet: q protocols control sending, Mobile network receiving of msgs v e. g. , Internet: q protocols control sending, Mobile network receiving of msgs v e. g. , TCP, IP, HTTP, Skype, Ethernet q Internet: “network of networks” v v loosely hierarchical public Internet versus private intranet Global ISP Home network Regional ISP Institutional network q Internet standards v RFC: Request for comments v IETF: Internet Engineering Task Force H. Fauconnier M 2 -Internet Introduction 1 -5

What’s the Internet: a service view q communication infrastructure enables distributed applications: v Web, What’s the Internet: a service view q communication infrastructure enables distributed applications: v Web, Vo. IP, email, games, e-commerce, file sharing q communication services provided to apps: v reliable data delivery from source to destination v “best effort” (unreliable) data delivery H. Fauconnier mobile network global ISP home network regional ISP institutional network M 2 -Internet Introduction 1 -6

A closer look at network structure: q network edge: applications and hosts q access A closer look at network structure: q network edge: applications and hosts q access networks, physical media: wired, wireless communication links q network core: v interconnected routers v network of networks H. Fauconnier mobile network global ISP home network regional ISP institutional network M 2 -Internet Introduction 1 -7

The network edge: q end systems (hosts): v v v run application programs e. The network edge: q end systems (hosts): v v v run application programs e. g. Web, email at “edge of network” peer-peer q client/server model v v client host requests, receives service from always-on server client/server e. g. Web browser/server; email client/server q peer-peer model: v v minimal (or no) use of dedicated servers e. g. Skype, Bit. Torrent H. Fauconnier M 2 -Internet Introduction 1 -8

Types d’accès mobile network q residential access nets global ISP q institutional access networks Types d’accès mobile network q residential access nets global ISP q institutional access networks (school, company) q mobile access networks Keep in mind: q bandwidth (bits per second) of access network? q shared or dedicated? H. Fauconnier home network regional ISP institutional network M 2 -Internet Introduction 1 -9

Access net: digital subscriber line (DSL) central office DSL splitter modem voice, data transmitted Access net: digital subscriber line (DSL) central office DSL splitter modem voice, data transmitted at different frequencies over dedicated line to central office v v v telephone network DSLAM ISP DSL access multiplexer use existing telephone line to central office DSLAM § data over DSL phone line goes to Internet § voice over DSL phone line goes to telephone net < 2. 5 Mbps upstream transmission rate (typically < 1 Mbps) < 24 Mbps downstream transmission rate (typically < 10 Mbps) Introduction 1 -10

Access net: cable network cable headend … cable splitter modem V I D E Access net: cable network cable headend … cable splitter modem V I D E O V I D E O D A T A C O N T R O L 1 2 3 4 5 6 7 8 9 Channels frequency division multiplexing: different channels transmitted in different frequency bands Introduction 1 -11

Access net: cable network cable headend … cable splitter modem data, TV transmitted at Access net: cable network cable headend … cable splitter modem data, TV transmitted at different frequencies over shared cable distribution network v v CMTS cable modem termination system ISP HFC: hybrid fiber coax § asymmetric: up to 30 Mbps downstream transmission rate, 2 Mbps upstream transmission rate network of cable, fiber attaches homes to ISP router § homes share access network to cable headend § unlike DSL, which has dedicated access to central office Introduction 1 -12

Access net: home network wireless devices to/from headend or central office often combined in Access net: home network wireless devices to/from headend or central office often combined in single box cable or DSL modem wireless access point (54 Mbps) router, firewall, NAT wired Ethernet (100 Mbps) Introduction 1 -13

Enterprise access networks (Ethernet) institutional link to ISP (Internet) institutional router Ethernet switch v Enterprise access networks (Ethernet) institutional link to ISP (Internet) institutional router Ethernet switch v v v institutional mail, web servers typically used in companies, universities, etc 10 Mbps, 100 Mbps, 1 Gbps, 10 Gbps transmission rates today, end systems typically connect into Ethernet switch Introduction 1 -14

Wireless access networks v shared wireless access network connects end system to router § Wireless access networks v shared wireless access network connects end system to router § via base station aka “access point” wide-area wireless access wireless LANs: § within building (100 ft) § 802. 11 b/g (Wi. Fi): 11, 54 Mbps transmission rate § provided by telco (cellular) operator, 10’s km § between 1 and 10 Mbps § 3 G, 4 G: LTE to Internet Introduction 1 -15

Host: sends packets of data host sending function: v takes application message v breaks Host: sends packets of data host sending function: v takes application message v breaks into smaller chunks, known as packets, of length L bits v transmits packet into access network at transmission rate R § link transmission rate, aka link capacity, aka link bandwidth packet transmission delay = two packets, L bits each 2 1 R: link transmission rate host time needed to transmit L-bit packet into link = L (bits) R (bits/sec) 1 -16

Physical Media q Bit: propagates between transmitter/rcvr pairs q physical link: what lies between Physical Media q Bit: propagates between transmitter/rcvr pairs q physical link: what lies between transmitter & receiver q guided media: v signals propagate in solid media: copper, fiber, coax Twisted Pair (TP) q two insulated copper wires v v Category 3: traditional phone wires, 10 Mbps Ethernet Category 5: 100 Mbps Ethernet q unguided media: v signals propagate freely, e. g. , radio H. Fauconnier M 2 -Internet Introduction 1 -17

Physical Media: coax, fiber Coaxial cable: Fiber optic cable: conductors q bidirectional q baseband: Physical Media: coax, fiber Coaxial cable: Fiber optic cable: conductors q bidirectional q baseband: pulses, each pulse a bit q high-speed operation: q two concentric copper v v single channel on cable legacy Ethernet q broadband: v multiple channels on cable v HFC H. Fauconnier q glass fiber carrying light v high-speed point-to-point transmission (e. g. , 10’s 100’s Gps) q low error rate: repeaters spaced far apart ; immune to electromagnetic noise M 2 -Internet Introduction 1 -18

Physical media: radio q signal carried in electromagnetic spectrum q no physical “wire” q Physical media: radio q signal carried in electromagnetic spectrum q no physical “wire” q bidirectional q propagation environment effects: v v v reflection obstruction by objects interference H. Fauconnier Radio link types: q terrestrial microwave v e. g. up to 45 Mbps channels q LAN (e. g. , Wifi) v 11 Mbps, 54 Mbps q wide-area (e. g. , cellular) v 3 G cellular: ~ 1 Mbps q satellite v Kbps to 45 Mbps channel (or multiple smaller channels) v 270 msec end-end delay v geosynchronous versus low altitude M 2 -Internet Introduction 1 -19

Commutation par paquets- par circuits? H. Fauconnier M 2 -Internet 1 -20 Commutation par paquets- par circuits? H. Fauconnier M 2 -Internet 1 -20

The network core v v mesh of interconnected routers packet-switching: hosts break application-layer messages The network core v v mesh of interconnected routers packet-switching: hosts break application-layer messages into packets § forward packets from one router to the next, across links on path from source to destination § each packet transmitted at full link capacity Introduction 1 -21

Packet-switching: store-and-forward L bits per packet source v v v 3 2 1 R Packet-switching: store-and-forward L bits per packet source v v v 3 2 1 R bps takes L/R seconds to transmit (push out) L-bit packet into link at R bps store and forward: entire packet must arrive at router before it can be transmitted on next link end-end delay = 2 L/R (assuming zero propagation delay) R bps destination one-hop numerical example: § L = 7. 5 Mbits § R = 1. 5 Mbps § one-hop transmission delay = 5 sec more on delay shortly … Introduction 1 -22

Packet Switching: queueing delay, loss A B C R = 100 Mb/s R = Packet Switching: queueing delay, loss A B C R = 100 Mb/s R = 1. 5 Mb/s queue of packets waiting for output link D E queuing and loss: v If arrival rate (in bits) to link exceeds transmission rate of link for a period of time: § packets will queue, wait to be transmitted on link § packets can be dropped (lost) if memory (buffer) fills up Introduction 1 -23

Two key network-core functions routing: determines source- forwarding: move packets from destination route taken Two key network-core functions routing: determines source- forwarding: move packets from destination route taken by packets § routing algorithms router’s input to appropriate router output routing algorithm local forwarding table header value output link 0100 0101 0111 1001 1 3 2 2 1 3 2 11 01 dest address in arriving packet’s header Network Layer 4 -24

Alternative core: circuit switching end-end resources allocated to, reserved for “call” between source & Alternative core: circuit switching end-end resources allocated to, reserved for “call” between source & dest: v v In diagram, each link has four circuits. § call gets 2 nd circuit in top link and 1 st circuit in right link. dedicated resources: no sharing § circuit-like (guaranteed) performance circuit segment idle if not used by call (no sharing) Commonly used in traditional telephone networks Introduction 1 -25

Circuit switching: FDM versus TDM Example: FDM 4 users frequency time TDM frequency time Circuit switching: FDM versus TDM Example: FDM 4 users frequency time TDM frequency time Introduction 1 -26

Packet switching versus circuit switching packet switching allows more users to use network! • Packet switching versus circuit switching packet switching allows more users to use network! • 100 kb/s when “active” • active 10% of time N users …. . example: § 1 Mb/s link § each user: 1 Mbps link v circuit-switching: § 10 users v packet switching: § with 35 users, probability > 10 active at same time is less than. 0004 * Q: how did we get value 0. 0004? Q: what happens if > 35 users ? * Check out the online interactive exercises for more examples Introduction 1 -27

Packet switching versus circuit switching is packet switching a “slam dunk winner? ” v Packet switching versus circuit switching is packet switching a “slam dunk winner? ” v v v great for bursty data § resource sharing § simpler, no call setup excessive congestion possible: packet delay and loss § protocols needed for reliable data transfer, congestion control Q: How to provide circuit-like behavior? § bandwidth guarantees needed for audio/video apps § still an unsolved problem Q: human analogies of reserved resources (circuit switching) versus on-demand allocation (packet-switching)? Introduction 1 -28

Internet structure: network of networks Question: given millions of access ISPs, how to connect Internet structure: network of networks Question: given millions of access ISPs, how to connect them together? access net … access net … … access net access net … access net …

Internet structure: network of networks Option: connect each access ISP to every other access Internet structure: network of networks Option: connect each access ISP to every other access ISP? access net … access net … … connecting each access ISP to each other directly doesn’t scale: O(N 2) connections. … … access net access net … … access net …

Internet structure: network of networks Option: connect each access ISP to a global transit Internet structure: network of networks Option: connect each access ISP to a global transit ISP? Customer and provider ISPs have economic agreement. access net … access net … … access net global ISP access net access net … access net …

Internet structure: network of networks But if one global ISP is viable business, there Internet structure: network of networks But if one global ISP is viable business, there will be competitors …. access net … access net access net … … ISP A access net ISP B ISP C access net access net … … access net

Internet structure: network of networks But if one global ISP is viable business, there Internet structure: network of networks But if one global ISP is viable business, there will be competitors …. which must be interconnected Internet exchange point access net … … net access net IXP access net … … ISP A IXP access net ISP B ISP C access net peering link access net … … access net

Internet structure: network of networks … and regional networks may arise to connect access Internet structure: network of networks … and regional networks may arise to connect access nets to ISPS access net … … access net IXP access net … … ISP A IXP access net ISP B ISP C access net regional net access net … … access net

Internet structure: network of networks … and content provider networks (e. g. , Google, Internet structure: network of networks … and content provider networks (e. g. , Google, Microsoft, Akamai ) may run their own network, to bring services, content close to end users access net … … access net IXP access net Content provider network IXP access net ISP B access net regional net access net … … access net … … ISP A access net

Internet structure: network of networks Tier 1 ISP IXP Regional ISP access ISP v Internet structure: network of networks Tier 1 ISP IXP Regional ISP access ISP v access ISP Google access ISP IXP Regional ISP access ISP at center: small # of well-connected large networks § “tier-1” commercial ISPs (e. g. , Level 3, Sprint, AT&T, NTT), national & international coverage § content provider network (e. g, Google): private network that connects it data centers to Internet, often bypassing tier-1, regional ISPs Introduction 1 -36

Tier-1 ISP: e. g. , Sprint POP: point-of-presence to/from backbone peering … … … Tier-1 ISP: e. g. , Sprint POP: point-of-presence to/from backbone peering … … … to/from customers H. Fauconnier M 2 -Internet Introduction 1 -37

Internet structure: network of networks q “Tier-2” ISPs: smaller (often regional) ISPs v Connect Internet structure: network of networks q “Tier-2” ISPs: smaller (often regional) ISPs v Connect to one or more tier-1 ISPs, possibly other tier-2 ISPs Tier-2 ISP pays tier-1 ISP for connectivity to rest of Internet q tier-2 ISP is customer of tier-1 provider Tier-2 ISP Tier 1 ISP Tier-2 ISP H. Fauconnier Tier-2 ISP Tier 1 ISP Tier-2 ISPs also peer privately with each other. Tier-2 ISP M 2 -Internet Introduction 1 -38

Internet structure: network of networks q “Tier-3” ISPs and local ISPs v last hop Internet structure: network of networks q “Tier-3” ISPs and local ISPs v last hop (“access”) network (closest to end systems) local ISP Local and tier 3 ISPs are customers of higher tier ISPs connecting them to rest of Internet H. Fauconnier Tier 3 ISP Tier-2 ISP local ISP Tier-2 ISP Tier 1 ISP Tier-2 ISP local ISP M 2 -Internet Introduction 1 -39

Internet structure: network of networks q a packet passes through many networks! local ISP Internet structure: network of networks q a packet passes through many networks! local ISP Tier 3 ISP Tier-2 ISP local ISP Tier-2 ISP Tier 1 ISP H. Fauconnier Tier-2 ISP local ISP Tier 1 ISP Tier-2 ISP local ISP M 2 -Internet Introduction 1 -40

Délais et pertes. . H. Fauconnier M 2 -Internet Introduction 1 -41 Délais et pertes. . H. Fauconnier M 2 -Internet Introduction 1 -41

How do loss and delay occur? packets queue in router buffers v v packet How do loss and delay occur? packets queue in router buffers v v packet arrival rate to link (temporarily) exceeds output link capacity packets queue, wait for turn packet being transmitted (delay) A B packets queueing (delay) free (available) buffers: arriving packets dropped (loss) if no free buffers Introduction 1 -42

Four sources of packet delay transmission A propagation B nodal processing queueing dnodal = Four sources of packet delay transmission A propagation B nodal processing queueing dnodal = dproc + dqueue + dtrans + dprop dproc: nodal processing § § § check bit errors determine output link typically < msec dqueue: queueing delay § time waiting at output link for transmission § depends on congestion level of router Introduction 1 -43

Four sources of packet delay transmission A propagation B nodal processing queueing dnodal = Four sources of packet delay transmission A propagation B nodal processing queueing dnodal = dproc + dqueue + dtrans + dprop dtrans: transmission delay: § L: packet length (bits) § R: link bandwidth (bps) § dtrans = L/R dtrans and dprop very different dprop: propagation delay: § d: length of physical link § s: propagation speed in medium (~2 x 108 m/sec) § dprop = d/s * Check out the Java applet for an interactive animation on trans vs. prop delay Introduction 1 -44

Caravan analogy 100 km ten-car caravan v v 100 km toll booth cars “propagate” Caravan analogy 100 km ten-car caravan v v 100 km toll booth cars “propagate” at 100 km/hr toll booth takes 12 sec to service car (bit transmission time) car~bit; caravan ~ packet Q: How long until caravan is lined up before 2 nd toll booth? toll booth § § § time to “push” entire caravan through toll booth onto highway = 12*10 = 120 sec time for last car to propagate from 1 st to 2 nd toll both: 100 km/(100 km/hr)= 1 hr A: 62 minutes Introduction 1 -45

Caravan analogy (more) 100 km ten-car caravan v v v toll booth 100 km Caravan analogy (more) 100 km ten-car caravan v v v toll booth 100 km toll booth suppose cars now “propagate” at 1000 km/hr and suppose toll booth now takes one min to service a car Q: Will cars arrive to 2 nd booth before all cars serviced at first booth? § A: Yes! after 7 min, 1 st car arrives at second booth; three cars still at 1 st booth. Introduction 1 -46

v v v R: link bandwidth (bps) L: packet length (bits) a: average packet v v v R: link bandwidth (bps) L: packet length (bits) a: average packet arrival rate average queueing delay Queueing delay (revisited) traffic intensity = La/R ~ 0: avg. queueing delay small La/R -> 1: avg. queueing delay large La/R > 1: more “work” arriving than can be serviced, average delay infinite! * Check out the Java applet for an interactive animation on queuing and loss La/R ~ 0 La/R -> 1 Introduction 1 -47

“Real” Internet delays and routes what do “real” Internet delay & loss look like? “Real” Internet delays and routes what do “real” Internet delay & loss look like? v traceroute program: provides delay measurement from source to router along endend Internet path towards destination. For all i: v § sends three packets that will reach router i on path towards destination § router i will return packets to sender § sender times interval between transmission and reply. 3 probes Introduction 1 -48

“Real” Internet delays, routes traceroute: gaia. cs. umass. edu to www. eurecom. fr 3 “Real” Internet delays, routes traceroute: gaia. cs. umass. edu to www. eurecom. fr 3 delay measurements from gaia. cs. umass. edu to cs-gw. cs. umass. edu 1 cs-gw (128. 119. 240. 254) 1 ms 2 border 1 -rt-fa 5 -1 -0. gw. umass. edu (128. 119. 3. 145) 1 ms 2 ms 3 cht-vbns. gw. umass. edu (128. 119. 3. 130) 6 ms 5 ms 4 jn 1 -at 1 -0 -0 -19. wor. vbns. net (204. 147. 132. 129) 16 ms 11 ms 13 ms 5 jn 1 -so 7 -0 -0 -0. wae. vbns. net (204. 147. 136) 21 ms 18 ms 6 abilene-vbns. abilene. ucaid. edu (198. 32. 11. 9) 22 ms 18 ms 22 ms 7 nycm-wash. abilene. ucaid. edu (198. 32. 8. 46) 22 ms trans-oceanic 8 62. 40. 103. 253 (62. 40. 103. 253) 104 ms 109 ms 106 ms link 9 de 2 -1. de. geant. net (62. 40. 96. 129) 109 ms 102 ms 104 ms 10 de. fr 1. fr. geant. net (62. 40. 96. 50) 113 ms 121 ms 114 ms 11 renater-gw. fr 1. fr. geant. net (62. 40. 103. 54) 112 ms 114 ms 112 ms 12 nio-n 2. cssi. renater. fr (193. 51. 206. 13) 111 ms 114 ms 116 ms 13 nice. cssi. renater. fr (195. 220. 98. 102) 123 ms 125 ms 124 ms 14 r 3 t 2 -nice. cssi. renater. fr (195. 220. 98. 110) 126 ms 124 ms 15 eurecom-valbonne. r 3 t 2. ft. net (193. 48. 50. 54) 135 ms 128 ms 133 ms 16 194. 211. 25 (194. 211. 25) 126 ms 128 ms 126 ms 17 * * means no response (probe lost, router not replying) 18 * * * 19 fantasia. eurecom. fr (193. 55. 113. 142) 132 ms 128 ms 136 ms * Do some traceroutes from exotic countries at www. traceroute. org Introduction 1 -49

Packet loss queue (aka buffer) preceding link in buffer has finite capacity v packet Packet loss queue (aka buffer) preceding link in buffer has finite capacity v packet arriving to full queue dropped (aka lost) v lost packet may be retransmitted by previous node, by source end system, or not at all v buffer (waiting area) A packet being transmitted B packet arriving to full buffer is lost * Check out the Java applet for an interactive animation on queuing and loss Introduction 1 -50

Throughput v throughput: rate (bits/time unit) at which bits transferred between sender/receiver § instantaneous: Throughput v throughput: rate (bits/time unit) at which bits transferred between sender/receiver § instantaneous: rate at given point in time § average: rate over longer period of time server, with server sends bits file of F bits (fluid) into pipe to send to client linkpipe that can carry capacity Rs bits/secat rate fluid Rs bits/sec) linkpipe that can carry capacity Rc bits/secat rate fluid Rc bits/sec) Introduction 1 -51

Throughput (more) v Rs < Rc What is average end-end throughput? Rs bits/sec v Throughput (more) v Rs < Rc What is average end-end throughput? Rs bits/sec v Rc bits/sec Rs > Rc What is average end-end throughput? Rs bits/sec Rc bits/sec bottleneck link on end-end path that constrains end-end throughput Introduction 1 -52

Throughput: Internet scenario per-connection endend throughput: min(Rc, Rs, R/10) v in practice: Rc or Throughput: Internet scenario per-connection endend throughput: min(Rc, Rs, R/10) v in practice: Rc or Rs is often bottleneck v Rs Rs Rs R Rc Rc Rc 10 connections (fairly) share backbone bottleneck link R bits/sec Introduction 1 -53

Protocoles, modèle en couches H. Fauconnier M 2 -Internet Introduction 1 -54 Protocoles, modèle en couches H. Fauconnier M 2 -Internet Introduction 1 -54

Protocol “Layers” Networks are complex! q many “pieces”: v hosts v routers v links Protocol “Layers” Networks are complex! q many “pieces”: v hosts v routers v links of various media v applications v protocols v hardware, software H. Fauconnier Question: Is there any hope of organizing structure of network? Or at least our discussion of networks? M 2 -Internet Introduction 1 -55

What’s a protocol? human protocols: q “what’s the time? ” q “I have a What’s a protocol? human protocols: q “what’s the time? ” q “I have a question” q introductions … specific msgs sent … specific actions taken when msgs received, or other events H. Fauconnier network protocols: q machines rather than humans q all communication activity in Internet governed by protocols define format, order of msgs sent and received among network entities, and actions taken on msg transmission, receipt M 2 -Internet Introduction 1 -56

What’s a protocol? a human protocol and a computer network protocol: Hi TCP connection What’s a protocol? a human protocol and a computer network protocol: Hi TCP connection request Hi TCP connection response Got the time? Get http: //www. awl. com/kurose-ross 2: 00 time Q: Other human protocols? H. Fauconnier M 2 -Internet Introduction 1 -57

Organization of air travel ticket (purchase) ticket (complain) baggage (check) baggage (claim) gates (load) Organization of air travel ticket (purchase) ticket (complain) baggage (check) baggage (claim) gates (load) gates (unload) runway takeoff runway landing airplane routing v a series of steps Introduction 1 -58

Layering of airline functionality ticket (purchase) ticket (complain) ticket baggage (check) baggage (claim baggage Layering of airline functionality ticket (purchase) ticket (complain) ticket baggage (check) baggage (claim baggage gates (load) gates (unload) gate runway (takeoff) runway (land) takeoff/landing airplane routing departure airport airplane routing intermediate air-traffic control centers arrival airport layers: each layer implements a service § via its own internal-layer actions § relying on services provided by layer below Introduction 1 -59

Why layering? dealing with complex systems: v explicit structure allows identification, relationship of complex Why layering? dealing with complex systems: v explicit structure allows identification, relationship of complex system’s pieces § layered reference model for discussion v modularization eases maintenance, updating of system § change of implementation of layer’s service transparent to rest of system § e. g. , change in gate procedure doesn’t affect rest of system v layering considered harmful? Introduction 1 -60

Internet protocol stack v application: supporting network applications § FTP, SMTP, HTTP v transport: Internet protocol stack v application: supporting network applications § FTP, SMTP, HTTP v transport: process-process data transfer § TCP, UDP v network: routing of datagrams from source to destination § IP, routing protocols v link: data transfer between neighboring network elements application transport network link physical § Ethernet, 802. 111 (Wi. Fi), PPP v physical: bits “on the wire” Introduction 1 -61

ISO/OSI reference model presentation: allow applications to interpret meaning of data, e. g. , ISO/OSI reference model presentation: allow applications to interpret meaning of data, e. g. , encryption, compression, machine-specific conventions v session: synchronization, checkpointing, recovery of data exchange v Internet stack “missing” these layers! v § these services, if needed, must be implemented in application § needed? application presentation session transport network link physical Introduction 1 -62

Encapsulation source message segment Ht M datagram Hn Ht M frame M Hl Hn Encapsulation source message segment Ht M datagram Hn Ht M frame M Hl Hn Ht M application transport network link physical switch destination M Ht M Hn Ht Hl Hn Ht M M application transport network link physical Hn Ht Hl Hn Ht M M network link physical Hn Ht M router Introduction 1 -63

Sécurité H. Fauconnier M 2 -Internet Introduction 1 -64 Sécurité H. Fauconnier M 2 -Internet Introduction 1 -64

Network Security q The field of network security is about: v how bad guys Network Security q The field of network security is about: v how bad guys can attack computer networks v how we can defend networks against attacks v how to design architectures that are immune to attacks q Internet not originally designed with (much) security in mind original vision: “a group of mutually trusting users attached to a transparent network” v Internet protocol designers playing “catch-up” v Security considerations in all layers! v H. Fauconnier M 2 -Internet Introduction 1 -65

Bad guys can put malware into hosts via Internet q Malware can get in Bad guys can put malware into hosts via Internet q Malware can get in host from a virus, worm, or trojan horse. q Spyware malware can record keystrokes, web sites visited, upload info to collection site. q Infected host can be enrolled in a botnet, used for spam and DDo. S attacks. q Malware is often self-replicating: from an infected host, seeks entry into other hosts H. Fauconnier M 2 -Internet Introduction 1 -66

Bad guys can put malware into hosts via Internet q Trojan horse v Hidden Bad guys can put malware into hosts via Internet q Trojan horse v Hidden part of some otherwise useful software v Today often on a Web page (Active-X, plugin) q Virus v infection by receiving object (e. g. , e-mail attachment), actively executing v self-replicating: propagate itself to other hosts, users H. Fauconnier q Worm: v infection by passively receiving object that gets itself executed v self- replicating: propagates to other hosts, users Sapphire Worm: aggregate scans/sec in first 5 minutes of outbreak (CAIDA, UWisc data) M 2 -Internet Introduction 1 -67

Bad guys can attack servers and network infrastructure q Denial of service (Do. S): Bad guys can attack servers and network infrastructure q Denial of service (Do. S): attackers make resources (server, bandwidth) unavailable to legitimate traffic by overwhelming resource with bogus traffic 1. select target 2. break into hosts around the network (see botnet) 3. send packets toward target from compromised hosts H. Fauconnier target M 2 -Internet Introduction 1 -68

The bad guys can sniff packets Packet sniffing: broadcast media (shared Ethernet, wireless) v The bad guys can sniff packets Packet sniffing: broadcast media (shared Ethernet, wireless) v promiscuous network interface reads/records all packets (e. g. , including passwords!) passing by v C A src: B dest: A v payload B Wireshark software used for end-of-chapter labs is a (free) packet-sniffer H. Fauconnier M 2 -Internet Introduction 1 -69

The bad guys can use false source addresses q IP spoofing: send packet with The bad guys can use false source addresses q IP spoofing: send packet with false source address C A src: B dest: A payload B H. Fauconnier M 2 -Internet Introduction 1 -70

The bad guys can record and playback q record-and-playback: sniff sensitive info (e. g. The bad guys can record and playback q record-and-playback: sniff sensitive info (e. g. , password), and use later v password holder is that user from system point of view A C src: B dest: A user: B; password: foo B H. Fauconnier M 2 -Internet Introduction 1 -71

Historique H. Fauconnier M 2 -Internet Introduction 1 -72 Historique H. Fauconnier M 2 -Internet Introduction 1 -72

Internet History 1961 -1972: Early packet-switching principles q 1961: Kleinrock - queueing theory shows Internet History 1961 -1972: Early packet-switching principles q 1961: Kleinrock - queueing theory shows effectiveness of packetswitching q 1964: Baran - packetswitching in military nets q 1967: ARPAnet conceived by Advanced Research Projects Agency q 1969: first ARPAnet node operational H. Fauconnier q 1972: v v ARPAnet public demonstration NCP (Network Control Protocol) first host-host protocol first e-mail program ARPAnet has 15 nodes M 2 -Internet Introduction 1 -73

Internet History 1972 -1980: Internetworking, new and proprietary nets q 1970: ALOHAnet satellite q Internet History 1972 -1980: Internetworking, new and proprietary nets q 1970: ALOHAnet satellite q q q network in Hawaii 1974: Cerf and Kahn architecture for interconnecting networks 1976: Ethernet at Xerox PARC ate 70’s: proprietary architectures: DECnet, SNA, XNA late 70’s: switching fixed length packets (ATM precursor) 1979: ARPAnet has 200 nodes H. Fauconnier Cerf and Kahn’s internetworking principles: v minimalism, autonomy - no internal changes required to interconnect networks v best effort service model v stateless routers v decentralized control define today’s Internet architecture M 2 -Internet Introduction 1 -74

Internet History 1980 -1990: new protocols, a proliferation of networks q 1983: deployment of Internet History 1980 -1990: new protocols, a proliferation of networks q 1983: deployment of q q TCP/IP 1982: smtp e-mail protocol defined 1983: DNS defined for name-to-IP-address translation 1985: ftp protocol defined 1988: TCP congestion control H. Fauconnier q new national networks: Csnet, BITnet, NSFnet, Minitel q 100, 000 hosts connected to confederation of networks M 2 -Internet Introduction 1 -75

Internet History 1990, 2000’s: commercialization, the Web, new apps q Early 1990’s: ARPAnet decommissioned Internet History 1990, 2000’s: commercialization, the Web, new apps q Early 1990’s: ARPAnet decommissioned q 1991: NSF lifts restrictions on commercial use of NSFnet (decommissioned, 1995) q early 1990 s: Web v hypertext [Bush 1945, Nelson 1960’s] v HTML, HTTP: Berners-Lee v 1994: Mosaic, later Netscape v late 1990’s: commercialization Late 1990’s – 2000’s: q more killer apps: instant messaging, P 2 P file sharing q network security to forefront q est. 50 million host, 100 million+ users q backbone links running at Gbps of the Web H. Fauconnier M 2 -Internet Introduction 1 -76

Internet history 2005 -present q ~750 million hosts v Smartphones and tablets q Aggressive Internet history 2005 -present q ~750 million hosts v Smartphones and tablets q Aggressive deployment of broadband access q Increasing ubiquity of high-speed wireless access q Emergence of online social networks: v Facebook: soon one billion users q Service providers (Google, Microsoft) create their own networks v Bypass Internet, providing “instantaneous” access to search, emai, etc. q E-commerce, universities, enterprises running their services in “cloud” (eg, Amazon EC 2) Introduction 1 -77

Les standard internet q Internet Engineering Task Force (IETF) (ouvert) q W 3 C Les standard internet q Internet Engineering Task Force (IETF) (ouvert) q W 3 C (industriels fermé) q RFC IETF: v Experimental v Proposed standard v Draft standard v Standard Informational v Historic q Niveau de recommandation v Not recommended v Limited use v Elective v Recommended v required H. Fauconnier M 2 -Internet Introduction 78

Internet 2011 Introduction 1 -79 Internet 2011 Introduction 1 -79

Internet 2011 Introduction 1 -80 Internet 2011 Introduction 1 -80

Facebook Introduction 1 -81 Facebook Introduction 1 -81

Facebook Introduction 1 -82 Facebook Introduction 1 -82

Facebook Introduction 1 -83 Facebook Introduction 1 -83