Internet terms, Networking Communications By P. Joshua Reginald Vignan University Guntur A.P
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Internet terms, Networking Communications
ByP. Joshua Reginald
Vignan University Guntur A.P
• '‘Computer network'' to mean a collection of autonomous computers interconnected by a single technology.
• Two computers are said to be interconnected if they are able to exchange information.
• The connection can be via a copper wire; fiber optics, microwaves, infrared, and communication satellites can also be used.
• Networks come in many sizes, shapes and forms
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Client-server model
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Peer to Peer systems(No client no server)
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Basic Terminology
• The 'Internet' is hardware
It is the interconnection of computer networks comprised of millions of computing devices.
Desktop computers, mainframes, smartphones, tablets, GPS units, car alarms, video game are connected to the Net.
The ARPANET
• The original ARPANET design.
The ARPANET
Growth of the ARPANET (a) December 1969. (b) July 1970.(c) March 1971. (d) April 1972. (e) September 1972.
Architecture of the Internet
• Overview of the Internet.
• A good place to start is with a client at home. Let us assume our client calls his or her ISP over a dial-up telephone line,
• The modem is a card within the PC that converts the digital signals the computer produces to analog signals that can pass unhindered over the telephone system.
• These signals are transferred to the ISP's POP (Point of Presence), where they are removed from the telephone system and injected into the ISP's regional network.
• From this point on, the system is fully digital and packet switched. If the ISP is the local telco, the POP will probably be located in the telephone switching office where the telephone wire from the client terminates.
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• If the ISP is not the local telco, the POP may be a few switching offices down the road
• The ISP's regional network consists of interconnected routers in the various cities the ISP serves.
• If the packet is destined for a host served directly by the ISP, the packet is delivered to the host. Otherwise, it is handed over to the ISP's backbone operator.
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Applications of Networks
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Resource SharingHardware (computing resources, disks, printers)Software (application software)
Information SharingEasy accessibility from anywhere (files, databases)Search Capability (WWW)
CommunicationEmailMessage broadcast
Remote computing
Distributed processing (GRID Computing)PJR
Networking Applications-Summary
E-mailSearchable Data (Web Sites)E-CommerceNews GroupsInternet Telephony (VoIP)Video ConferencingChat GroupsInstant Messengers Internet Radio
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LAN, MAN & WAN
Network Hardware- Types of Networks
Network in small geographical Area (Room, Building or aCampus) is called LAN (Local Area Network)
Network in a City is call MAN (Metropolitan Area Network)
Network spread geographically (Country or across Globe) iscalled WAN (Wide Area Network)
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Local Area Networks
Two broadcast networks(a) Bus(b) Ring
A metropolitan area network based on cable TV
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Wide Area Networks
Relation between hosts on LANs and the subnet.
Wide Area Networks (2)
A stream of packets from sender to receiver.
HTTP
• http is a technical acronym that means 'hypertext transfer protocol', the language of web pages. When a web page has this prefix, then your links, text, and pictures should work in your web browser.
• https is 'hypertext transfer protocol SECURED'. This means that the web page has a special layer of encryption added to hide your personal information and passwords.
• Whenever you log into your online bank or your web email account, you should see https at the front of the page address.
HTML and XML• Hypertext Markup Language is the
programmatic language that web pages are based on. HTML commands your web browser to display text and graphics in orderly fashion. HTML uses commands called 'HTML tags' that look like the following:
• <body></body>
• <a href="www.lifewire.com"></a>
• <title></title>
• XML is eXtensible Markup Language, a cousin to HTML.
• XML focuses on cataloging and databasing the text content of a web page. XML commands look like the following:
• <entry>
• <address>
• <city>
• XHTML is a combination of HTML and XML.
URL
• URL's, or 'uniform resource locators', are the web browser addresses of internet pages and files.
• A URL works together with IP addresses to help us name, locate, and bookmark specific pages and files for our web browsers.
• URL's commonly use three parts to address a page or file: the protocol (which is the portion ending in '//:'); the host computer (which sometimes ends in .com); and the filename/pagename itself.
• Example:https://personal.bankofamerica.com/login/password.htm
• Email (formerly spelled e-mail with a hyphen) is electronic mail.
• It is the sending and receiving of typewritten messages from one screen to another.
• Email is usually handled by a webmail service (e.g. Gmail or Yahoomail), or an installed software package (e.g. Microsoft Outlook).
• Email has many cousins: text messaging, instant messaging, live chat, videomail (v-mail), Google Waving.
BLOG
• A blog ('web log') is a modern online writer's column.
• Amateur and professional writers publish their blogs on most every kind of topic: their hobby interest in paintball and tennis, their opinions on health care, their commentaries on celebrity gossip, photo blogs of favorite pictures, tech tips on using Microsoft Office.
• Absolutely anyone can start a blog, and some people actually make reasonable incomes by selling advertising on their blog pages.
ISP
• ISP is Internet Service Provider. That is the private company or government organization that plugs you into the vast Internet around the world.
• Your ISP will offer varying services for varying prices: web page access, email, hosting your own web page, hosting your own blog, and so on.
• ISP's will also offer various Internet connection speeds for a monthly fee. (e.g. ultra high-speed Internet vs economy Internet).
Malware
• Malware is the broad term to describe any malicious software designed by hackers.
• Malware includes: viruses, trojans, ratware, keyloggers, zombie programs, and any other software that
Malware will do
• vandalize your computer in some way
• steal your private information
• take remote control of your computer for other ends
• manipulate you into purchasing something
Addons
• Addons are custom software modifications. The user optionally installs addons to improve the power of their Web browsers or office software.
• Examples include: a custom eBay toolbar for your Firefox browser, a new search feature for your Outlook email.
• Most addons are free and can be found and downloaded from the Web.
• Plugins are a special kind of web browser addon. Pluginsare essentially required addons if you wish to view very specialized web pages.
• Examples include: Adobe Flash or Shockwave player, Microsoft Silverlight player, Adobe Acrobat pdf reader.
Trojan
• A trojan is a special kind of hacker program that relies on the user to welcome it and activates it.
• Named after the famous Trojan horse tale, a trojan program masquerades as a legitimate file or software program.
• Sometimes it will be an innocent-looking movie file or an installer that pretends to be actual anti-hacker software.
• The power of the trojan attack comes from users naively downloading and running the trojan file.
SPAM
• Spam' has two meanings. • 1) Spam can mean 'the rapid repetition of a keyboard
command'. But more commonly, • 2) spam is the jargon name of 'unwanted/unsolicited
email'.• Spam email is usually comprised of two sub-categories:
high-volume advertising, and hackers attempting to lure you into divulging your passwords.
• Filtering is the popular-but-imperfect defense against spam.
• Filtering uses software that reads your incoming email for keyword combinations, and then either deletes or quarantines messages that appear to be spam. Look for a 'spam' or 'junk' folder in your mailbox to see your quarantine of filtered email.
Firewall
• Firewall - A firewall is a piece of software that blocks unwanted traffic a computer and intranet.
• Most modern computers come with a firewall already installed, and there are numerous third party firewall applications available online.
Phishing
• Phishing - Phishing refers to a type of online scam where criminals pose as representatives of legitimate businesses or organizations in order to obtain sensitive user information.
• Some of the more common phishing scams involve the imitation of popular websites (Facebook, Amazon, PayPal, etc) by slightly altering the spelling or structure of the original site's web address.
IP Addresses
• In IPv4 an address consists of 32 bits which limits the address space to4294967296 (232) possible unique addresses.
• IPv4 addresses are canonically represented in dot-decimal notation, which consists of four decimal numbers, each ranging from 0 to 255, separated by dots
e.g., 172.16.254.1.
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IP Addresses
IP address formats
The IP Version 4 Protocol (1)
The IPv4 (Internet Protocol) header.
The IP Version 4 Protocol
• An IPv4 datagram consists of a header part and a body or payload part.
• The header has a 20-byte fixed part and a variable-length optional part.
• The bits are transmitted from left to right and top to bottom.
Version field
Version field keeps track of which version of the protocol the datagram belongs to.
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The IP Version 4 ProtocolIHL
tells how long the header is, in 32-bit words.
Differentiated services
• Also called as Type of service field
Total length
The maximum length is 65,535 bytes.
Identification
• allow the destination host to determine which packet a newly arrived fragment belongs to. All the fragments of a packet contain the same Identification value
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IP Version 6 Goals• Support billions of hosts
• Reduce routing table size
• Simplify protocol
• Better security
• Attention to type of service
• Aid multicasting
• Roaming host without changing address
• Allow future protocol evolution
• Permit coexistence of old, new protocols. . .
IP Version 6
The IPv6 fixed header (required).
DNS – The Domain Name System
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• Generally Programs theoretically could refer to hosts, mailboxes, and other resources by their network (e.g., IP) addresses, these addresses are hard for people to remember
• sending e-mail to [email protected] means that if Tana's ISP or organization moves the mail server to a different machine with a different IP address, her e-mail address has to change.
• Consequently, ASCII names were introduced to decouple machine names from machine addresses.
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• some mechanism is required to convert the ASCII strings to network addresses.
• DNS is primarily used for mapping host names and e-mail destinations to IP addresses but can also be used for other purposes
• DNS is defined in RFCs 1034 and 1035
• To map a name onto an IP address, an application program calls a library procedure called the resolver,
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The DNS Name Space
A portion of the Internet domain name space.
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• Internet is divided into over 200 top-level domains.
• Each domain covers many hosts.
• Each domain is partitioned into sub domains, and these are further partitioned, and so on.
• All these domains can be represented by a tree .
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• The top-level domains come in two flavors: generic and countries.
• The original generic domains(7+1(R)) were
com (commercial),
edu (educational institutions),
gov (the U.S. Federal Government),
int (certain international organizations),
mil (the U.S. armed forces)
net (network providers), and
org (nonprofit organizations).
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Communications
• Simplex
• Half duplex
• Duplex
Communications
➢Transfer of information
➢Simplex (Ex:Pager)
➢Half duplex( Walkie talkie)
➢Duplex(Cell phone)
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WIRELESS TECHNOLOGY
Introduction
➢Wireless is defined as “having no wires”.
➢The term is used to describe communication where
there is no physical wired connection between sender
and receiver, rather the network is connected by radio or
microwaves.
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