© 2007 Cisco Systems, Inc. All rights reserved.Cisco Public ITE PC v4.0 Chapter 1 1 Application Layer Functionality and Protocols Network Fundamentals – Chapter 3

ITE PC v4.0 Chapter 1 2 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public  Define the application layer as the source and destination of data for communication across networks.  Explain the role of protocols in supporting communication between server and client processes.  Describe the features, operation, and use of well-known TCP/IP application layer services and protocols (HTTP, DNS, SMTP,Telnet, DHCP, FTP/TFTP, SMB, Gnutella). Applications – The Interface Between Human and Data Networks

ITE PC v4.0 Chapter 1 3 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Applications – services - protocols  Applications: end user application programs (GUI)  Services: background programs used by the applications –Ex: DNSclient, workstation service, printspooler,…  Application layer: interface for programs –to transfer data to the network by user request –To exchange data between S en D programs/services by means of protocols. (rules to interact).

ITE PC v4.0 Chapter 1 4 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public processes  Software running concurrently: User applications Services System operations  1 program/service can run serveral times, in different processes. –Ex: svchost.exe

ITE PC v4.0 Chapter 1 5 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public

ITE PC v4.0 Chapter 1 6 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public  PRESENTATION LAYER 1.Coding & conversion (ascii, formformats) 2.Compression 3.Encryption Ex: 1+2: jpeg, mpeg, gif1:tiff3:ssl  SESSION LAYER dialog/session control between source and destination applications: 1.Initiate 2.Keep active 3.Restart when idle

ITE PC v4.0 Chapter 1 7 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Two models for applications: client/server model & peer-to-peer model

ITE PC v4.0 Chapter 1 8 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public

ITE PC v4.0 Chapter 1 9 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Peer to peer networking vs peer to peer (P2P) applications Peer to peer applications can be used in either peer to peer or client/server networks.

ITE PC v4.0 Chapter 1 10 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Name resolution  NAAM (netbiosnaam / FQDN)  IP (logisch adres)  MAC (fysisch adres)

ITE PC v4.0 Chapter 1 11 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Netbios-naam (vlak) IPadres MAC adres Omzetting door middel van broadcast Omzetting door middel van broadcast, nl door ARP arp –a (=tijdelijk cache geheugen opvragen die wordt aangelegd na een ARP broadcast) Nbtstat –c nbtstat –a netbiosnaam Ping netbiosnaam IN LAN !!!!

ITE PC v4.0 Chapter 1 12 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Netbios-naam IPadres MAC adres BROADCASTS LIMITEREN: op alle PC's LMHOSTS bestand met IPadres computernaam Installeren van een WINS server met dynamische database. Alle clients moeten het WINSipadres kennen. (knooppunttypes) Omzetting door middel van broadcast, nl door ARP Deze omzetting blijft altijd broadcast, daarnaast gebruik makend van een ARPcache.

ITE PC v4.0 Chapter 1 13 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public PC /24 DG: werkgroepPCs SUBNET A PC /24 DG: PC /24 DG: PC /24 DG: werkgroepPCs SUBNET B PC /24 DG: PC /24 DG: router / /24 Vanuit subnet A: PING (lukt) PING PC4(lukt niet omdat de netbiosnaam via broadcast moet worden omgezet en de router stopt broadcasts.)OPL lmhost of WINS

ITE PC v4.0 Chapter 1 14 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public FQDN IPadres eerst routering tot in LAN dan MAC adres Omzetting enkel door middel van een statisch HOSTS bestand op alle computers of een DNSserver. Alle clients moeten het ipadres van de DNSserver kennen. Omzetting door middel van broadcast, nl door ARP

ITE PC v4.0 Chapter 1 15 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Cache query

ITE PC v4.0 Chapter 1 16 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public DNS = domain name service  DNS service for applications that need name resolving + DNS protocol

ITE PC v4.0 Chapter 1 17 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public 1 Domain-namespace structure 1 distributed db FQDN = hostname. SLD. TLD. or alias

ITE PC v4.0 Chapter 1 18 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Domain vs zone  Domain = part of namespace  Zone = db file with RESOURCE RECORDS for one or more domains.  DNSserver = AUTHORATIVE for one or more domains. Records in zone db file.

ITE PC v4.0 Chapter 1 19 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Example: RR: A; NS; CNAME ; MX

ITE PC v4.0 Chapter 1 20 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Query: recursief vs iteratief Cache ?Authorative ?Root of Forwarders ?

ITE PC v4.0 Chapter 1 21 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public

ITE PC v4.0 Chapter 1 22 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Tool: nslookup (client / recursief / A)  Vraag de rootservers op.  Vraag de DNS server op, bevoegd voor mijn domeinnaam.  Vraag het IP adres op van de server waarop mijn website staat.  Tool instellen om te werken als een DNSserver en niet als een client  Vraag het IP adres op van de server

ITE PC v4.0 Chapter 1 23 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public

ITE PC v4.0 Chapter 1 24 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Scenario – opbouw: 1PC naar Internet

ITE PC v4.0 Chapter 1 25 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Scenario – opbouw:split namespace website hosting door ISP

ITE PC v4.0 Chapter 1 26 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Scenario – opbouw: DNS door ISP, website in eigen netwerk.

ITE PC v4.0 Chapter 1 27 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Scenario – opbouw: DNS /website in eigen netwerk.

ITE PC v4.0 Chapter 1 28 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Scenario – opbouw: DNS /website in eigen netwerk.

ITE PC v4.0 Chapter 1 29 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public HTTP/HTTPS  Conversation between browser and webserver  Get: webpage opvragen  Post: inhoud formulier doorsturen  Put: wijzigingen aan webpagina doorsturen

ITE PC v4.0 Chapter 1 30 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public

ITE PC v4.0 Chapter 1 31 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public

ITE PC v4.0 Chapter 1 32 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public

ITE PC v4.0 Chapter 1 33 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public

ITE PC v4.0 Chapter 1 34 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public

ITE PC v4.0 Chapter 1 35 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public

ITE PC v4.0 Chapter 1 36 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public

ITE PC v4.0 Chapter 1 37 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Webserver: verschillende webpagina’s toegankelijk maken via 1 IPadres poort 80  Mogelijkheden: Meerdere publieke IPadressen 1 publiek IPadres – verschillende poortnummers: Werken met hostheaders.

ITE PC v4.0 Chapter 1 38 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public SMTP (simple mail transfer protocol) POP (post office protocol)

ITE PC v4.0 Chapter 1 39 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public MX records opvragen !!!

ITE PC v4.0 Chapter 1 40 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public FTP file transfer protocol 21 20

ITE PC v4.0 Chapter 1 41 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public  Active mode FTP (default !)  Passive mode FTP

ITE PC v4.0 Chapter 1 42 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public

ITE PC v4.0 Chapter 1 43 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public DHCP Caution: When PC powered down ; address returned to the pool This is not fully correct !!!! Depends on lease-time

ITE PC v4.0 Chapter 1 44 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Gratuitous arp  Detectie IP conflicten: indien ontvangen arp source adres = eigen IP  Bij Clusters: meerdere fysieke interfaces koppelen aan 1 logisch IP. Bij wijziging van interface moeten andere devices op de hoogte worden gebracht. ARP caches updaten.  Bij opstarten; down/up: nic driver maakt zich kenbaar naar anderen.

ITE PC v4.0 Chapter 1 45 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Telnet: terminal emulation (cfr console maar vanop afstand), zonder encryptie !!!

ITE PC v4.0 Chapter 1 46 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Secure telnet: SSH (secure shell)

ITE PC v4.0 Chapter 1 47 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public File sharing / SMB (server message block)

ITE PC v4.0 Chapter 1 48 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Gnutella protocol: gedecentraliseerd P2P HYBRIDE (met centrale index db) GNUTELLA (niet afh van centrale index db) peer discovery

ITE PC v4.0 Chapter 1 49 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public SNMP: network management protocol Top talkers throughput on interfaces load of protocols Top conversations