CS 1.3 Network Protocols

• HTTP (Hypertext Transfer Protocol)


  An insecure protocol used between a browser and web server. Hypertext Transfer Protocol transmits HTML web pages from web server to client
• HTTPS (Hypertext Transfer Protocol Secure)


  Secure version of HTTP, the traffic is encrypted between the browser and the web server for security. Now fairly standard
• TCP (Transmission Control Protocol)


  This sets up and maintains a reliable connection between two computers, e.g. client's browser and web server
• IP(Internet Protocol)


  This protocol describes how to route packets of data around networks. It's used by routers and switches to direct packets
• IMAP(Internet Message Access Protocol)


  Alternative email protocol to POP, the client can read emails but they stay on the server.
• FTP(File Transfer Protocol)


  Protocol for transferring files to and from a file server.
• SMTP(Simple Mail Transfer Protocol)


  Rules for sending emails from client to server, and then server to server.
• POP(Post Office Protocol)


  Used by client to download emails from mail server, less useful than IMAP
• Wi-Fi


  Wireless connection standards are known by this 4-letter acronym, this describes how wireless devices connect
• Ethernet


  The protocols used at the lowest layer of a network, describing the rules for connecting hardware and cables
• Protocol


  A set of agreed rules which allow two devices to communicate.
• Bluetooth


  Wireless PAN technology that transmits signals over short distances between smartphones, computers and other devices.
• Encryption


  Converting readable data into unreadable characters to prevent unauthorized access. Authorised recipients can reverse the process with the key. HTTPS uses it
• IP address


  Number that uniquely identifies each device connected to a network. IPv4 format is 4 bytes, IPv6 uses 16 bytes for more addresses.
• IPv4


  A version of the IP protocol that uses 32-bit (4-byte) addresses such as 104.16.15.221. There are only around 4 billion possible IPv4 addresses and we are running out, so IPv6 is now preferred
• IPv6


  The latest version of the IP protocol, it uses 128 bits (16 bytes) for every address so they will never run out. Addresses are shown as 4 pairs of hex bytes like this: a490::65d8:4282:7f30
• 128


  Number of bits in an IPv6 address
• 32


  Number of bits in an IPv4 address
• 4 billion


  Approximate number of IPv4 addresses, because IPv4 is limited to 32 bits giving 2^32 possible values
• Standard


  Published document that says how hardware or software must behave or interact, e.g. the Wi-Fi rules 802.11, the HTML structure and the cable types Cat 5e and Cat 6.
• Layer


  A level in the protocol stack. Protocols in each of these perform related services, and each must talk to the one above and below.
• TCP/IP


  The 4-layer "protocol stack" that makes the internet work. Includes Ethernet, IP, TCP and HTTP which all have a role to play in delivering a services over the web