1 © 2001 John Urrutia. All rights reserved. Chapter 7 Networking and the InterNet.

1© 2001 John Urrutia. All rights reserved.

Chapter 7

Networking Networking and theand theInterNetInterNet


TopicsBackground

Common Types of Networks

Communications Over the Network

Networking Utilities

Distributed Computing


Topics (cont.)Nertwork Services / DAEMONS

InterNet Services

The World Wide Web

Creating your own Web Page


BackgroundSneaker-Net (pre-tty)

Slow

Unreliable transmission

Serial transmissionFaster than slow (100’s BPS)

More reliable


BackgroundMost companies run several

networks in their environmentLAN, MAN, WAN

Intranet – Link company infrastructure

Internet – Link the company to the outside world

Fast – (10’s MBS – 1 GBS)


BackgroundNetwork services

Linux runs special processes called daemons

These are continually running processes that handle the sharing of system resources such as file systems

They make remote file systems appear as attached to local computers


BackgroundNetwork services

New utilities developed to handle the networked environment

rwho – rlogin – telnet – rcp – ftp


BackgroundIntranets

Access is restricted to internal users.

Similar to LANs but uses internet protocol and technology.

Provides Inter-operability (Macs, PC, Linux, etc.)Local e-mail Web-page development and access


TopicsBackground






Common Types of NetworksNetwork topologies – Broadcast

Ethernet

Single wire – Party line

All systems have access to all traffic

Messages sent at will

Collisions require re-sends which can cause network instability


Common Types of NetworksNetwork topologies – Token ring

FDDI –Fiber Distributed Data Interface

Single wire – Party line

All systems have access to all traffic

Messages sent only when token captured

Token passing can fail which cause delays in network traffic


Common Types of NetworksNetwork topologies – Point to point

Two endpoints only

Dedicated line between points

Well governed – limited traffic

Topologically limited to small number of connections (2 log N )


Point to Point


Common Types of NetworksLocal Area Networks ( LANs)

Run over:Thicknet (Coaxial cable) or Thinnet

(10BASE2) Unshielded Twist Pair

UTP, Category 5, 10BASET Fiber Optic Cable Infrared Radio


Common Types of NetworksLocal Area Networks ( LANs)

Designed to support a small network within a small geographical areaOfficeStoreHome


Common Types of NetworksEthernet

Ethernet technology runs at 10MBS but throughput is less do to collisions

Messaging is processed by packets. Each of which contain a destination address

Ethernet ImprovementsAllow up to 1GBS over UTP


Common Types of NetworksFDDI

Peak data rate is 100MBS

DrawbacksCost of CableCost of interface cardsDifficult to install and maintain

Technology Available over copper


Common Types of NetworksWide Area Networks ( WANs)

Designed to cover a large geographic area. Across states or countries or around the

world

Generally Point-to-PointLeased linesSatellite


Common Types of NetworksMetropolitan Area Networks ( MANs)

Designed to cover a medium geographic area. Across buildings or within a city

Generally Point-to-PointLeased linesRadio


Common Types of NetworksGateways

Allow interoperability across disparate hardware devices or networks.

Translates protocols from LAN to WAN

Re-packets messages


Common Types of NetworksRouters

Hi speed switching station connecting 2 or more networks

Constantly monitor traffic across the networks

Route datagrams (messages) to the least used pathway



Common Types of NetworksNetwork Protocols

Protocol is the set of rules defining how systems or networks communicate with each otherEthernet, Telnet, FTP, TCP– Transport Control Protocol HTTP – Hyper-Text Transfer Protocol PPP – Point to Point Protocol SLIP – Serial Line Internet Protocol


Common Types of NetworksHost Addresses

Every message sent over the network has a 32 bit destination address (IPv4). Using the Internet Protocol the address is made up of 4 bytes of data

Addresses may be static or dynamic

Addresses are contolled by the NICNetwork Information Center



Addresses belong to 1 of 4 classes A,B,C,DIdentified by the number of 1 bits in the

highorder byte

The max number of networks allowed on the Internet is 2,113,664

The max number of host computers is 3,758,096,400


Host Addresses31 24 23 16 15 8 7 0

0 Netid Host ID

Bit

Class A:

10 Netid Host IDClass B:

110 Netid Host IDClass C:

1110 Multicast addressClass D:

111110 ReservedClass E:



127.37.16.231 is a valid IP Address but it is hard to remember

The /etc/hosts file provides the fully qualified host name along with a symbolic nickname

Updating symbolics is a daunting taskNIS – Network Information ServiceDNS – Domain Name Services


TopicsBackground






Communicating Over the Network

Many of the standard communications utilities have been extended to handle remote computing.pine, finger, talk

Some systems do not identify themselves in their prompt.hostname



Using finger to learn about Remote Usersfinger @Linux2

Provides information about remote system logins.

Querys the network services

finger daemon runs remotely.



finger the NEIS at USGS to find almost real-time earthquake info

World Wide mail using pine

Talking around the world talk


TopicsBackground






Networking UtilitiesMany of the utilities have been

extended to provide network access

New utilities created to monitor and control the network environment


Networking UtilitiesUsing rlogin and telnet to

Access Remote Computersrlogin is used to connect UNIX and

UNIX-like systems

telnet is used to connect non-UNIX systems

Both utilities make your host session appear to be on the remote system


Networking UtilitiesYou must be trusted to use rcp rsh

Trusted systems are identified by the /etc/hosts.equiv file.

Trusted Hosts and the ~/.rhost FileIdentifies the host name and user id


Networking UtilitiesUsing ftp to Transfer Files

…]$ ftp linux2ascii / binarygetputbye?


Networking UtilitiesUsing rsh to run commands

remotely


Networking UtilitiesUsing ping to Test a Network

ConnectionUses ICMP – internet control message

protocol


Networking UtilitiesUsing rwho to list Users on Remote

Systems


TopicsBackground






Distributed ComputingThe Client/Server Model

Servers store and provide information to clients

Clients access information through servers


Distributed ComputingDomain Name Services (DNS)

Hierarchy.com.edu.gov.mil.net.org


Distributed ComputingNetwork Information Service (NIS)

Developed by Sun Microsystems

Keeps system independent configuration files current

Access information throughypcatypmatch


Distributed ComputingNetwork File System (NFS)

Makes available remote file systems as local filesystems



InterNet Services

The World Wide Web



Network Services / DAEMONSInetd

Listens for service requestsAutomatically starts other daemons to

provide services


Network Services / DAEMONSnamed

Supports the DNSThis replaces the old /etc/hosts table


Network Services / DAEMONSin.nntpd

Network News Transfer Protocol

Provide exchange service of USENET articles

Intelligently downloads files


Network Services / DAEMONSrouted

Manages routing tables

gatedManages gateway configurations


Network Services / DAEMONSsmtpd

Simple Mail Transfer Protocol



InterNet Services

The World Wide Web



Internet ServicesUSENET

Formed in the 1980’s

Similar to an electronic bulletin board


Internet ServicesArchie

Public domain database of over 1000 FTP sites

Tell you where to find stuff


Internet ServicesGopher

Retrieves selected documents based on your criteria



InterNet Services

The World Wide Web



Overview of the WWWBrowser terminology

Screen Elements

Navigating the WEB

Reading News

Downloading files

Bookmarks


Overview of the WWWSearch Engines

Alta Vista

LYCOS

Excite

HotBot

Google


Creating Your Own Web PageNetscape

MS Word

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1 © 2001 John Urrutia. All rights reserved. Chapter 7 Networking and the InterNet.

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