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Chapter 14 Networking and Internetworking

Chapter 14 Networking and Internetworking. Credits: Parts of the slides are based on slides created by UNIX textbook authors, Syed M. Sarwar, Robert Koretsky, Syed A. Sarwar, 2005 Addison Wesley. expanded by Jozef Goetz, 2012. Objectives.

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Chapter 14 Networking and Internetworking

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  1. Chapter 14 Networking and Internetworking Credits: Parts of the slides are based on slides created by UNIX textbook authors, Syed M. Sarwar, Robert Koretsky, Syed A. Sarwar, 2005 Addison Wesley expanded by Jozef Goetz, 2012

  2. Objectives • You may ignore all slides with commands started with r* • To describe networks, the Internet and internetworks and explain why they are used • To discuss briefly the TCP/IP protocol suite, IP addresses, protocol ports, and internet services and applications • To explain what the client-server software model is and how it works • To discuss various network software tools for electronic communication , • remote login, • file transfer, • remote command execution , and • status reporting • To describe briefly the secure shell • To cover the commands and primitives

  3. Computer Networks and Internet works • When two or more computer hardware resources are connected they form a computer network • Local area Networks (LANs) • Metropolitan area networks (MANs) • Wide area networks (WANs) • An internetwork is a network of networks

  4. A brief history of the Internet • ARPANET (50s and 60s, some universities) • NSFNET (late 70s, all universities) • TCP/IP (invention ’74) became the official protocol in 1983. • When NSFNET and the ARPANET were connected, the growth became exponential • Many regional networks (Canada, Europe, the Pacific) joined up • In mid-80s people began viewing the collection of networks as the Internet • The glue that holds the Internet togetheris the TCP/IP reference model and TCP/IP protocol stack • ANS (Advanced Networks and Service) by MERIT, MCI, and IBM took overNSFNET in 1990 as ANSNET • ANSNET sold to American Online in 1995.

  5. The ARPANET • The original ARPANET design. IMP - Interface Message Processor

  6. The ARPANET • Growth of the ARPANET (a) December 1969. (b) July 1970. (c) March 1971. (d) April 1972. (e) September 1972.

  7. NSFNET • The NSFNET backbone in 1988.

  8. Internet Usage • Machine is on the Internet if • it runs the TCP/IP protocol stack, • has an IP address, and • can send IP packets to all the other machines on the Internet • Millions PC can call up an Internet service provider using a modem, be assigned atemporary (dynamic) IP address, and send IP packets to all the other hosts

  9. Internet Usage • Traditional applications (1970 – 1990) • E-mail • News • newsgroups devoted to different topics) • Remote login • Using telnet, WinSCP, rlogin, ssh programs • File transfer • Using FTP programs

  10. Internet Usage • Early ’90s new application the WWW (World Wide Web) • invented by physicist Tim Berbers-Lee brought millions of nonacademic users • They started using the Mosaic browser (GUI) and then other browsers • The ch-r of the network was changed from an academic and military playground to a public utility

  11. Architecture of the Internet. • A NAP (Network Access Point) is a room full of routers, at least one per backbone • A LAN in the room connects all the routers, • so packetscan be forwarded from any backboneto any other backbone • Overview of the Internet. • Signal is transferred to the ISP’s (Internet Service Provider) POP – Point of Present(located in the tel. switching office) and injected into the ISP’s regional network • from this point the system is fully digital and packet switched

  12. Collection of Subnetworks The Internet is an interconnected collection of many networks. SNA: Systems Network Architecture -IBM's mainframe network standards

  13. X.25 Networks • Developed during 70's. 1st public data network interface between public packet-switched networks and customers. Data packet has a 3-byte header • a 12 bit connection #, • a packet sequence #, • an acknowledgment # etc. and up to 126 bytes of data • Operate at 64 Kbps, so are very slow and becoming outdated. However there are still many of them in operation. • Connection oriented: Uses: • Switched Virtual Circuit • established when the first packet is sent • circuitremains for duration of session providing in-order delivery, and flow control. • Permanent Virtual Circuit • established by agreement between the customer and the carrier: • Like a leased line

  14. Frame Relay • Takes advantage of modern high-speed reliabledigital phonelines. Connection oriented. Property: In-order delivery, no error control, no flow control, akin to LAN • This allows simple protocolswith work done by user computersrather than by the network. • Runs at 1.5 Mbps with few features. • Customer leasesapermanent virtual circuit between two points. • this "virtual leased line" means that the wire is shared with other users at a great price reduction.

  15. Broadband ISDN and ATM Connection oriented. • ISDN(Integrated Services Digital Network) • offers cable, video on demand, e-mail, etc. • ATM (Asynchronous Transfer Mode) early ’90s is underlying • Mechanism inside the tel. system. • Transmits in small fixed-size cells. Not synchronous. • Was supposed to merge voice, data, cable TV, telex, telegraph etc. into a single integrated system – it didn’t happen • Alive, used by carriers for internal transport

  16. (a) Computer Networks and (b) Internetworks R - routers

  17. Why Computer Networks and Internetworks? • Sharing of computer resources • computers, printers, plotters, scanners, files and software • Network as a communicationmedium • inexpensive, fast, reliable • Cost efficiency • large computing power available • Less performance degradation • if one computer crashes, the remaining ones are still up

  18. Network Models • International Standards Organization’s Open System InterconnectReference Model (ISO’s OSI 7-Layer Reference Model) • The TCP/IP 5-layer Model • Used in the Internet

  19. Network Models with approximate mapping between the two • The first 4 layers deal with the communication between hosts. • The 5th layer deals with the Internet services provided by various applications. • Most of the 1st layer is handled by hardware (communication medium used, attachments of hosts to the medium). • The rest of the 1st layerand all the 2nd layer is handled by the (Network Interface Card) NICcard in a host. • Layers 3 and 4 are fully implemented in the operating systems kernelon most existing systems. • The first 2 layers are network hardware specific, the others are work independently of the physical layer

  20. Reference Models • Protocols and networks in the TCP/IP model initially. • The Application layer contains all of the higher-level protocols • – telnet - virtual terminal protocol • – FTP – file transfer • – SMTP – e-mail • – DNS - Domain Name System • – NNTP - Network News Transfer Protocol • – HTTP - Hypertext Transfer Protocol

  21. The TCP/IP Protocol Suite • As a user you can see the application layer in the form of applications and utilities • Web browsing, • file transfer, • remote login • etc. 1st -2nd layer is handled by the Network Interface Card -NIC card

  22. The TCP/IP Protocol Suite • IGMP - Internet Group Management Protocol • handlesmulticasting • ICMP - Internet Control Message Protocol • Handles errorsandcontrol messages. • Protocol is used to forward information, primarily error messages. • To see if a computer is running, the `ping' program sends an echo request, which is part of ICMP. • ARP -Address Resolution Protocol is a protocol for mapping an Internet Protocol IP address to a physical machine address (MAC) that is recognized in the local network. • For example, in IP Version 4, the most common level of IP in use today, an address is 32 bits long. • In an EthernetLAN, however, addresses for attached devices are 48 bits • RARP - Reverse Address Resolution Protocol is a protocol by which a physical machine in a LAN can request to learn its IP addressfrom a gatewayserver's Address Resolution Protocol (ARP) table or cache. • A network administrator creates a table in a LAN’s gateway router that maps the physical machine (MAC addresses) into IP addresses. 1st -2nd layer is handled by the Network Interface Card -NIC card

  23. Transport Layer: The TCP and UDP • The purpose of the transport layer is to transport applicationdata from your machine to a remote machine and vice versa • User Datagram Protocol(UDP) is a connectionless protocol, offers the best effortdelivery service • Transmission Control Protocol (TCP) is a connection-oriented protocol that establish a virtualconnection with the destination before transmitting data, • thus the TCP leads • completelyreliable, • error free • in-sequence delivery of data

  24. Routing of the Application DataThe Internet Protocol (IP) • The network layer is responsible for routing application data to the destination host • IP is responsible for transporting IP datagrams containing TCP segments or UDP datagrams to the destination host • The IP is a connectionless protocol, it simply sends the application data without establishing virtual connection with the destination before transmitting data, • thus the IP routing is the best effortand doesn’t guarantee delivery of TCP segments or UDP datagrams

  25. Routing of the Application DataThe Internet Protocol (IP) • In IPv4 the IP address (32 bits) is divided into three fields: • address class, • network ID and • host ID • The address classfield identifies the class of the address and dictates the number of bits used in the network ID and host ID fields • This scheme has 5 address classes : A,B,C,D,E

  26. IPv4 Addresses in Dotted Decimal Notation • 32-bit binary numbers are difficult to remember • IPv4 addresses are given in dotted decimal notation (DDN) • In DDN all 4 bytes of an IPv4 address are written in their decimal equivalents and are separated by dots • Example: 192.102.10.21

  27. IP Addresses IP address formats. • 127.0.0.0 (or 127.x.x.x, where x is between 0-127) is known as localhost is used to send a data packet to itself. for testing purpose. • hostID = 1…1 is the broadcast address in order to send a data packet to all hosts on a network

  28. IPv4 Address Classes The sum of network IDs for class A, B, C = 2^7 + 2^14 + 2^21 = 1,113,664 networks The sum of hosts IDs for class A, B, C = 2^24 + 2^16 + 2^ 8 = 3,758,096,400 hosts

  29. IPv4 Address Classes Prove all ranges!!!

  30. IPv4 Address Classes • A: Very large organizations and government agencies • B: Large organizations: AT&T, IBM, MIT, large universities etc. • C: Small to medium sized organizations: ISP, small consulting companies, • community colleges, universities • In IPv4 the IP address (32 bits) • In IPv6 the IP address is 128 bits and it covers the # of hosts 6 x 2^28times the present world population

  31. IPv4 Address Classes Figure 14.5  An internetwork of 4 networks with one class A, one class B, and 2 class C networks connected via 4 routers class C class A class C class B

  32. Symbolic Names • Symbolic names are easier to remember • remain the same even if the numeric address changes • must be unique for a host on the Internet • Format: hostname.domain_name e.g.students.up.edu where: domain_name = organization_name.top-level_domain • organization_nameis assigned by the Network Information Center e.g. laverne.edu • Attaching the name of a host to a domain name with a period between them yields the Fully Qualified Domain Name (FQDN) for the host • e.g.egr.up.edu – egr is a host name at the University of Portland

  33. A portion of the Internet domainname hierarchy

  34. Top-Level Internet Domains

  35. The Domain Name System • Domain Name System (DNS)servicetranslatessymbolicnamesto equivalent IP addresses • DNS implements a distributed database of name-to-address mappings • A set of dedicated hosts run name serversthat take requests from the application software • and work together to map domain names tothe corresponding IP addresses • every organization runs at least 1 name server • app uses gethostbyname() to get its IP address

  36. Inverse domain • The servers that handle the inverse domain are also hierarchical. • This means the netidpart of the address should be at a higher level than the subnetid part, and the subnetid part higher than the hosted part. • In this way, a server serving the whole site is at a higher level than the servers serving each subnet. • To follow the convention of reading the domain labels from the bottomto the top, an IP address such as 132.34.45.121 (a class 13: address with netid 132.34) is read as 121.45.34.132.in-addr. area. • This configuration makes the domain look inverted when compared to a generic or country domain.

  37. DNS lookup utility: host [cs253u@shell cs253u]$ host ecs.fullerton.edu ecs.fullerton.edu has address 137.151.27.1 [cs253u@shell cs253u]$ host 137.151.27.1 1.27.151.137.in-addr.arpa domain name pointer ecs.fullerton.edu. [cs253u@shell cs253u]$ [jgoetz jgoetz]$ host ulv.edu ulv.edu has address 192.231.179.66 ulv.edu mail is handled (pri=5) by mxg1.ulv.edu ulv.edu mail is handled (pri=5) by mxg2.ulv.edu [jgoetz jgoetz]$ host 192.231.179.66 66.179.231.192.IN-ADDR.ARPA domain name pointer www.ulv.edu

  38. The Domain Name System #DNS service is to use a statichostfile /etc/hosts #a static hosts file contains the domain names and their IP addresses configured by the system admin $ cat /etc/hosts [jgoetz jgoetz]$ cat /etc/hosts 127.0.0.1 localhost 192.231.179.91 raq4.ulv.edu # Cobalt automated entry for eth0 192.231.179.81 loki.ulv.edu loki #Veritas Backup Server #to view IP address and other info about host’s interface to the network $ /sbin/ifconfig –a # faculty.ulv.edu has 192.231.179.91 [jgoetz jgoetz]$ /sbin/ifconfig -a eth0 Link encap:Ethernet HWaddr 00:10:E0:05:A8:F4 inet addr:192.231.179.91 Bcast:192.231.179.95 Mask:255.255.255.224 UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:212947098 errors:0 dropped:0 overruns:0 frame:0 TX packets:318162567 errors:3 dropped:0 overruns:0 carrier:3 collisions:0 txqueuelen:100 Interrupt:5 Base address:0x8000 eth1 Link encap:EthernetHWaddr 00:10:E0:05:A8:F3 BROADCAST MULTICAST MTU:1500 Metric:1 RX packets:0 errors:0 dropped:0 overruns:0 frame:0 TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:100 Interrupt:9 Base address:0x8100 lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 UP LOOPBACK RUNNING MTU:3924 Metric:1 RX packets:1749416 errors:0 dropped:0 overruns:0 frame:0 TX packets:1749416 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 $

  39. The Domain Name System [cs253u@shell cs253u]$ cat /etc/hosts # Do not remove the following line, or various programs # that require network functionality will fail. 127.0.0.1 localhost.localdomain localhost shell 192.168.3.25 ldap.int.ecs.fullerton.edu ldap 192.168.3.29 ecsmysql.ecs.fullerton.edu ecsmysql 192.168.3.30 mail.ecs.fullerton.edu mail 137.151.28.223 lupus.ecs.fullerton.edu lupus 192.168.3.200 lupus2.ecs.fullerton.edu lupus2 • [jgoetz@raq4 ~]$ host 192.231.179.91 • 91.179.231.192.IN-ADDR.ARPA domain name pointer FACULTY.ULV.EDU

  40. The Domain Name System • #lookupfor the IP address of a host name: • [cs253u@shell cs253u]$ nslookup ecs.fullerton.edu • Server: 192.168.3.26 # name server • Address: 192.168.3.26#53 • Name: ecs.fullerton.edu • Address: 137.151.27.1 • [jgoetz jgoetz]$ nslookup ulv.edu • Server: ns.ulv.edu • Address: 64.69.149.200 • Name: ulv.edu • Address: 192.231.179.66 • [jgoetz@raq4 ~]$ nslookup faculty.ulv.edu • Server: ns.ulv.edu # this a nameserver • Address: 64.69.149.200 • Name: faculty.ulv.edu • Address: 192.231.179.91 #nslookup uses file /etc/resolv.conf to find the host that runs the name server and passes the request over it. [jgoetz jgoetz]$ cat /etc/resolv.conf domain ulv.edu search ulv.edu nameserver 64.69.149.200 nameserver 64.69.154.123 [jgoetz jgoetz]$

  41. The Domain Name System • nslookup uses file /etc/resolv.conf to find the host that runs the name server and passes the request over it. • [cs253u@shell cs253u]$ cat/etc/resolv.conf nameserver 192.168.3.26 • diginteracts with name servers specified in /etc/resolv.conf and display their responses – gives more infothan nslookup

  42. The Domain Name System • [jgoetz jgoetz]$ dig ulv.edu • ; <<>> DiG 8.3 <<>> ulv.edu • ;; res options: init recurs defnam dnsrch • ;; got answer: • ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 4 • ;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 2, ADDITIONAL: 2 • ;; QUERY SECTION: • ;; ulv.edu, type = A, class = IN • ;; ANSWER SECTION: • ulv.edu. 12H IN A 192.231.179.66 • ;; AUTHORITY SECTION: • ulv.edu. 12H IN NS ns2.ulv.edu. • ulv.edu. 12H IN NS ns.ulv.edu. • ;; ADDITIONAL SECTION: • ns.ulv.edu. 12H IN A 64.69.149.200 • ns2.ulv.edu. 12H IN A 64.69.154.123 • ;; Total query time: 11 msec • ;; FROM: raq4.ulv.edu to SERVER: default -- 64.69.149.200 • ;; WHEN: Thu Nov 15 16:21:26 2007 • ;; MSG SIZE sent: 25 rcvd: 108 [jgoetz@raq4 ~]$ dig faculty.ulv.edu ; <<>> DiG 8.3 <<>> faculty.ulv.edu ;; res options: init recurs defnam dnsrch ;; got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 4 ;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 2, ADDITIONAL: 2 ;; QUERY SECTION: ;; faculty.ulv.edu, type = A, class = IN ;; ANSWER SECTION: faculty.ulv.edu. 1D IN A 192.231.179.91 ;; AUTHORITY SECTION: ulv.edu. 1D IN NS ns.ulv.edu. ulv.edu. 1D IN NS ns2.ulv.edu. ;; ADDITIONAL SECTION: ns.ulv.edu. 1D IN A 64.69.149.200 ns2.ulv.edu. 1D IN A 64.69.154.123 ;; Total query time: 25 msec ;; FROM: raq4.ulv.edu to SERVER: default -- 64.69.149.200 ;; WHEN: Wed Nov 16 22:25:25 2005 ;; MSG SIZE sent: 33 rcvd: 116

  43. The Domain Name System • [jgoetz jgoetz]$ dig ulv.edu • ; <<>> DiG 8.3 <<>> ulv.edu • ;; res options: init recurs defnam dnsrch • ;; got answer: • ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 4 • ;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 2, ADDITIONAL: 2 • ;; QUERY SECTION: • ;; ulv.edu, type = A, class = IN • ;; ANSWER SECTION: • ulv.edu. 12H IN A 192.231.179.66 • ;; AUTHORITY SECTION: • ulv.edu. 12H IN NS ns2.ulv.edu. • ulv.edu. 12H IN NS ns.ulv.edu. • ;; ADDITIONAL SECTION: • ns.ulv.edu. 12H IN A 64.69.149.200 • ns2.ulv.edu. 12H IN A 64.69.154.123 • ;; Total query time: 11 msec • ;; FROM: raq4.ulv.edu to SERVER: default -- 64.69.149.200 • ;; WHEN: Thu Nov 15 16:21:26 2007 • ;; MSG SIZE sent: 25 rcvd: 108 dig ecs.fullerton.edu ; <<>> DiG 9.2.4 <<>> ecs.fullerton.edu ;; global options: printcmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 29854 ;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 1, ADDITIONAL: 0 ;; QUESTION SECTION: ;ecs.fullerton.edu. IN A ;; ANSWER SECTION: ecs.fullerton.edu. 86400 IN A 137.151.27.1 ;; AUTHORITY SECTION: ecs.fullerton.edu. 86400 IN NS ecs.fullerton.edu. ;; Query time: 22 msec ;; SERVER: 192.168.3.26#53(192.168.3.26) ;; WHEN: Fri Mar 14 23:54:21 2008 ;; MSG SIZE rcvd: 65

  44. Well-known Internet Services

  45. The Client-Server Software Model • Internet servicesare implemented by using a paradigm in which the software for a service is partitioned into 2 parts • The part that runs on the host on which the user running the application is logged on to is called the client software • The part that’s usually starts running when a host boots is called the server software • Connection-oriented client server models: • client sends a connection request to the server and • the server either rejects or accepts the request. • If server accepts the request, the client and server are said to be connected through a virtual connection

  46. The Client-Server Software Model http://faculty.ulv.edu/

  47. Displaying the Names. uname [OPTION]... DESCRIPTION Print certain system information. With no OPTION, same as -s. -a, --all print all information -m, --machine print the machine (hardware) type -n, --nodename print the machine's network node hostname -r, --release print the operating system release -s, --sysname print the operating system name -p, --processor print the host processor type -v print the operating system version --help display this help and exit --version output version information and exit [jgoetz jgoetz]$ uname Linux [jgoetz jgoetz]$ uname -n raq4.ulv.edu [jgoetz jgoetz]$ uname -a [jgoetz jgoetzLinux raq4.ulv.edu 2.2.16C37_V #1 Sat Apr 12 15:06:43 PDT 2003 i686 unknown

  48. Displaying the Host Name $ uname -n yamsrv1.ece.gatech.edu $ uname -a SunOS yamsrv1.ece.gatech.edu 5.8 Generic_108528-22 sun4u sparc SUNW,Ultra-250 $ hostname– name of the host you are logged on to yamsrv1.ece.gatech.edu [jgoetz jgoetz]$ hostname raq4.ulv.edu -a, --all print all information -m, --machine print the machine (hardware) type -n, --nodename print the machine's network node hostname --help

  49. cpu info. [jgoetz jgoetz]$ less /proc/cpuinfo [cs253u@shell cs253u]$ less /proc/cpuinfo processor : 1 vendor_id : AuthenticAMD cpu family : 15 model : 35 model name : Dual Core AMD Opteron(tm) Processor 175 stepping : 2 cpu MHz : 2211.280 cache size : 1024 KB fdiv_bug : no hlt_bug : no f00f_bug : no coma_bug : no fpu : yes fpu_exception : yes cpuid level : 1 flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext lm 3dnowext 3dnow lahf_ lm pni /proc/cpuinfo (END)

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