CHAPTER 18 PC’s ON THE INTERNET



CHAPTER 18 PC’s ON THE INTERNET

TCP/IP is the language of the internet

In general IP(internet protocol) handles Routing.

TCP(transmission control protocol) handles Reliability.

IP identifies networks & individual hosts using IP addresses

TCP identifies individual services using tcp port numbers

Other Protocols that help IP do it’s job

ARP – Address Resolution Protocol – matches IP address to MAC address

RARP – reverse ARP – matches MAC address to IP address

ICMP – internet control message protocol – carries error & diagnostic information

TCP uses socket numbers to identify a particular service on a source or target computer

A socket number = ip address: tcp port number example 10.100.10.250:80

Well known port numbers range from 1 – 1024 & are reserved

Port numbers 1025-65536 are open for use

TCP/IP ARCHITECTURE

Application protocols

• HTTP Hypertext Transfer Protocol 80

• SMTP Simple Mail Transfer Protocol 25

• TELNET

• DNS 53

• SNMP 25

• FTP File Transfer Protocol 20

Transport protocols

• TCP connection

• UDP connectionless

Internetwork protocols

• IP

• HELPERS

TCP/IP UTILITIES

• Ping – test connectivity

• Tracert – tests connectivity & displays the route taken to get to the destination

• Nslookup – displays information about IP addressing and DNS domain names

• IPconfig – Microsoft command (windows 2000, XP, 2003, vista) displays tcp/ip configuration settings

WAYS TO CONNECT TO THE INTERNET

• Dialup

• Cable modem

• DSL

• ISDN

• Satellite access

• Wireless access

DIAL UP PROTOCOLS

• Slip – serial line internet protocol

o Not secure

o Obsolete

• Ppp – point to point protocol

o Secure

o More efficient than slip

o Dominates today

CABLE MODEM & DSL PROTOCOLS

• PPPOE – point to point protocol over Ethernet

WEB PAGE CACHING

Server side caching – the web server caches or stores web pages in case you wish to view them again

Client side caching – the web browser stores web pages for you to view later

ROUTERS – connect different networks

Hardware – anycomputer with 2 or more nics can act as a router

Software – routers can be dedicated computers or they can be network servers that offer other services as well

WINDOWS XP NETWORK SERVICES

ICS – internet connection sharing

• Allows an XP computer with a connection to the internet to act like a router if other computers can connect to that XP computer on the local LAN

• Limited to very small (10 or less) groups of computers

• Very simple to configure, but configuration is automatic and cannot be changed

ICF – internet connection firewall

• A software firewall that will block incoming packets that are not in response to a request form your XP computer

• Greatly improved in service pack 2

VPNS – virtual private network

A secure, logical connection form 1 computer to another: originally designed to use the internet as it’s infrastructure

VPNS use tunneling & encryption

While there are 4 types of VPNS, these tow are the most popular

• PPTP – point to point tunneling protocol

• L2TP & IPSEC

o L2TP – layer 2 tunneling protocol

o IPSEC – IP security for encryption

VPNS are a type of remote access

Remote access to networks requires a secure way to provide a username & password to login

AUTHENTICATION PROTOCOLS

• EAP – smart cards

• MSCHAP 1 & 2

• CHAP

• SPAP

WEB BROWSERS

Graphic tools used to view world wide web sites

URL – uniform resource locator

Each web page is identified by a unique URL

TROUBLESHOOTING BROWSER PROBLEMS

• Scan for viruses often

• Keep the browser up to date

• Reinstall the browser if necessary

SECURE WEB OPERATIONS (HTTPS)

• Uses SSL (secure sockets layer, uses digital certificates)

• New version of SSL is: TLS (transport layer security)

E-MAIL

• Uses SMTP or SMTP AUTH, for e-mail messages sent to an E-MAIL server

• Uses POP3 or IMAP for E-MAIL messages that are downloaded from an email server by the recipient

FTP – becoming obsolete

• A tcp/ip service that works at the command prompt to allow users to upload and download files to and from a FTP server

VOIP – voice over IP

• A protocol that allows voice communications over a network

• Requires that each digital phone be assigned a telephone number from the VOIP provider

• Uses dynamic IP addressing

• Uses ferrite clamps to reduce EMI

REMOTE DESKTOP

• Gives a user access to their XP computer from anywhere on the internet

• Requires static IP address

• Must be enabled in My computer, properties, remote

• Start remote desktop – start – programs – accessories – communications – remote desktop.

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