Concept of Internet and Networking PDF

CONCEPT OF INTERNET AND NETWORKING MANAGEMENT OF THE INTERNET How individuals connect to an ISP? Ownership of the Internet Point of presence (POP) - modems, servers, - Local networks are owned by routers, and switches Individuals...

CONCEPT OF INTERNET AND NETWORKING MANAGEMENT OF THE INTERNET How individuals connect to an ISP? Ownership of the Internet Point of presence (POP) - modems, servers, - Local networks are owned by routers, and switches Individuals ISPs maintain multiple POPs throughout the Universities geographic area they serve Government agencies Private companies - Infrastructure (high-speed data lines) is owned by Government entities Privately held companies Management of the Internet - Nonprofit organizations and user groups Internet uses Client/server model Each have a specialized purpose - Clients are Previously handled by U.S. government Devices such as computers, tablets, and contractors smartphones Guarantees worldwide engagement in the Clients use browsers to request services direction of the Internet - Types of servers Paying for the Internet Web servers: Run specialized operating - National Science Foundation (NSF) systems to host web pages and other Pays for large part of infrastructure information Funds research and development for new Commerce servers: Software that enables technologies users to buy goods and services; use security - Other countries participate as well protocols to protect sensitive information File servers: Provide remote storage; cloud storage DATA TRANSMISSION AND PROTOCOLS Network follows standard protocols to send information Protocol is a set of rules for exchanging electronic information INTERNET NETWORKING INTERACT "rules of the road" for the information How computers are superhighway connected to the Internet? Internet is a "network of networks" Main paths known collectively as Internet backbone Problems in developing an open system Internet protocol Agreeing on standards was easy Developing a new method of communication was difficult - Circuit switching (technology available in the 1960s) was ineflicient for computer communication Circuit Switching TCP/IP Protocol the Internet uses for transmitting data - Main suite of protocols is TCP/IP Why Circuit switching is inefficient for Transmission Control Protocol (TCP) computers? Internet Protocol (IP) - Consists of many interrelated protocols What computers use to communicate? Packet switching makes computer communicate efficient Data is broken into smaller chunks (packets) Doesn't require a dedicated communications circuit INTERNET IDENTITY Packets are sent over various routes at same IP Address time Each device connected They are reassembled at the destination by to Internet required to receiving computer have a unique number Fulfilled original goal of Internet: Data can Called the IP Address still travel to destination if a node is disabled Domain names are or destroyed word-based IP addresses IP address Typical IP address: 197.169.73.63 Benefits of dynamic Dotted decimal number (dotted quad) addressing Binary form is Provides more secure 11000101.10101001.01001001.00111111 environment Referred to as an octet Helps keep hackers out of Considered 32-bit numbers system Can represent 4,294,967,296 values Because of limited number of IP addresses... Classless inter-domain routing (CIDR) was developed Allows single IP address to represent How computer knows IP address of another several computer? unique IP addresses (supernetting) Computer converts URL to IP address by Other Adds Internet a network prefix to end of last octet (/ consulting database on domain name system addressing systems (DNS) server Internet Protocol version 6 (IPv6), Functions like a phone book for the Internet developed by lETF, uses 128-bit addressing Root DNS server: knows location of DNS instead of 32-bit servers that contain master listings for TLD XXXX:XXXX:XXXX:XXXX:XXXX:XXX X:XXXX:XXXX Each X is a hexadecimal digit Hexadecimal is base-16 number system Uses 0-9 or A-F IPV6 Makes much larger number of IP addresses available (340 followed by 36 zeros) All modern operating systems handle both IPv4 and IPv6 COMMUNICATIONS OVER THE Majority of routing still uses IPV4 INTERNET E-MAIL IPv6 conversion will accelerate as IPv4 Invention of e-mail addresses are running out Ray Tomlinson (1971) helped develop ARPANET (precursor to the Internet) How my computer gets an IP address? Enables users to leave text messages for each other on a single machine Extended to sending text messages between machines on Internet Became the most popular application 1973: Accounted for 75% of all data traffic Simple Mail Transfer Protocol (SMTP) sends e-mails along the Internet Part of the Internet Protocol suite Is a client/server application Passes through several e-mail servers How dynamic addresses are assigned Handled by Dynamic Host Configuration Protocol (DHCP) Belongs to TCP/IP protocol suite Takes from pool of available addresses on as- needed basis Assigns address for duration of session Might not be the same from session to session Sending files as attachments COMMUNICATIONS O VER THE SMTP handles text messages INTERNET INSTANT MESSAGING Multipurpose Internet Mail Extensions What you need to run instant messaging? (MIME) specification created to send files Client program that connects to an instant E-mail is sent as text, but MIME handles messaging (IM) service encoding and decoding of files Examples Email is highly susceptible to being read Yahoo! Messenger It is sent in plain text Google Talk Copies might exist on numerous servers Windows Live Messenger Encryption helps protect sensitive How instant messaging works? messages Client software makes connection with chat Many e-mail servers offer built-in server encryption Provides connection information to your Codes e-mail so that only person with key device to code can decode the message Server isn't involved in chat session Private-key encryption Chatting takes place between two devices Only the two parties have the code over the Internet Could be a shift code Could be more complex substitution code Main problem is key security Two keys (key pair) are created One for coding, one for decoding Coding key is distributed as public key Message being sent is coded using public key Decode using private key Only receiver knows private key Mathematical relationship between two keys Private-key's level of security Impossible to deduce private key from public key because of complexity of algorithms In brute force attack every possible combination is tried Can enable hackers to deduce key and decode message