The Internet and World Wide Web Flashcards
What is a network?
a collection of computers and devices in order to communicate
Examples of devices that can be in a network (4)
modems, cables, telephone lines, and satellites
a worldwide collection of networks that links millions of businesses, government agencies, etc
Internet (“Net”)
Services on the Internet? (5)
e-mail, file transfer (FTP), instant messaging, chat, and web
networking project by Pentagon’s Advanced Research Projects Agency (ARPA). Allowed scientists to share info. Built to function even if part was disabled or destroyed. Became functional in September 1969
DARPANET
4 host nodes for arpanet
University of California, Los Angeles, (U.C.L.A.), the Stanford Research Institute (S.R.I.) in Menlo Park, Calif., U.C. Santa Barbara (UCSB), and the University of Utah
5 supercomputers connected to ARPANET in 1986 creating ________
NSFNET (National Science Foundation’s Network)
Internet Structure today?
- networks from corporations, commercial firms, etc
- satellite companies
- phone companies
How has the network grown?
1969 - 4 host nodes
1984 - more than 1000 host nodes
Who controls the internet?
no single entity owns it, W3C controls HTML, and Internet2 controls delivery and communication
Who is Tim-Berners Lee?
- created the World Wide Web
- director of the W3C at MIT
- developed HTML
first browser
Mosaic
second browser
Netscape
What is an internet service provider (ISP)?
a business that has a permanent Internet connection. Provides temporary connections to people
access to internet through one or more telephone numbers
Regional ISP
local telephone numbers
National ISP
leading service provider
America Online
used phone for connectivity
Dial up access
How many groups of numbers are there in an IP address?
4
Examples of networks (3)
Local area network (LAN)
Virtual Private Network (VPN)
The Internet
Network components
Client computer Server computer Network interface card (NIC) Network operating system (NOS) Connection medium Hub or switch connecting multiple computers in a network Routers
Device that forwards data “packets” between computer networks for internetwork communication
router
simplest and slowest physical connection media
Twisted-pair wire (modems)
copper wires surrounded by thick insulation
Coaxial cable
Wireless transmission media and devices (3)
Microwave
Satellites
Cellular telephones
Method of communication that breaks a transmitted message into separate units (called packets), and allows each packet to follow any available network route that may lead to the destination
Upon arrival at the destination, the packets are reorganized into the original message
Previously circuit-switched networks required a dedicated path (circuit) through the network
Packet switching is dynamic and can efficiently use the network capacity and availability
Packet switching
Plaintext information floating around the internet can be captured by tools known by systems administrators, but also hackers
The need for encrypting sensitive information becomes more understood when considering plaintext can be viewed (e.g., credit card info in websites only using http, or in plaintext email)
May violate campus or corporate regulations
Packet Sniffers
Daughter of poet Lord Byron Many call her the first programmer Worked with Charles Babbage Ada computer language Famous colleagues (Dickens, Faraday) Died at 36, would have been 199
Ada Lovelace
criminal caught by bits
dennis rader
Needs for privacy and security
Protection from against external/internal hackers
Defending against industrial espionage
Protecting E-commerce assets
Verifying bank accounts/electronic transfers
Securing intellectual property
Preventing issues regarding liability
Ubiquity of email/networks and privacy
Cloud-based storage of private information
Insecure technologies (e.g., wireless)
Emergence of a paperless society
deals with creating documents that can be shared secretly over public communication channels
Cryptographic documents are decrypted with the key associated with encryption, with the knowledge of the encryptor
The word cryptography comes from the Greek words: Krypto (secret) and graphein (write)
cryptography
deals with finding the encryption key without the knowledge of the encryptor
cryptanalysis
deals with cryptography and cryptanalysis
cryptology
computer systems used to encrypt data for secure transmission and storage
cryptosystems
text that is in readable form
plaintext
results from plaintext by applying the encryption key
ciphertext
is the method of hiding secret messages in an ordinary document
Steganography does not use encryption explicitly, but rather through hiding information into an existing document
Steganography does not generally increase file size for hidden messages
Example: select the bit patterns in pixel colors to hide the message
steganography
can be used for both encryption and decryption
symmetric key
requires a different key for both encryption and decryption
asymmetric system
are used in algorithms to convert a plaintext document into a secret document
keys
A substitution cipher where each plaintext letter is replaced by some letter a fixed number of spaces down in the alphabet
caesar cipher
Rotates characters by 13 places
ROT13
the same key used for encryption/decryption
Problem of key distribution – how to get the key safely into hands of both parties
private key
a public key used for encryption and private key for decryption
Key distribution problem solved
Very popular technique:
Large Prime Numbers
Public (asymmetric) key
Issued by trusted third parties known as Certificate Authorities (CAs)
Verisign is a trusted third party
Used to authenticate an individual or an organization
Digital Certificates are usually given for a period of one year
They can be revoked
It is given at various security levels. The higher the security level, the CA verifies the authenticity of the certificate seeker more
digital certificates
Potential Problems with cryptographic technologies?
False sense of security if badly implemented
Government regulation of cryptographic technologies/export restrictions
Encryption prohibited in some countries
