Introduction to Networking Part 1
By: Mushr00m
Note: After my basic networking tutorials (May be around 15-20 of them) are written I will move onto network security, and how to use this knowledge to test network vulnerability
Components of a Network
1. Nodes (Host/Host computers)
-Servers: provide service for clients. Examples: file servers, print servers, web servers, e-mail servers, and directory servers.
-Clients: Input/Output (I/O) device at the user end.
2. Links (The path through which the message travels)
-Cables
-Space (if using WiFi)
-Hubs
-Switches
-Routers
-Gateways
Click below for basic network topology
(Picture source: http://www.aquafruit.com.au/blog/wp-cont...ure-16.png)
Spoiler (Click to View)
Client Server vs. Peer-to-peer
1. Client & Server Coordinate
-The server provides services such as the web, printing, storage, and access control.
-Clients access these services.
2. Peer-to-peer (Host/Host computers)
-No proprietary servers
-Computers take turns to provide access to servers.
Types of Networks
1. Local Area Network (LAN)
-Small networks that are usually only the size of a room or building. A LAN is composed of a group of PC's that are attached to the same circuit.
2. Backbone Network (BN)
-A backbone network usually can stretch from a couple hundred meters, to a few kilometers. It is a high speed backbone that connects LANs at different locations.
3. Metropolitan Area Network (MAN)
-MANs can stretch anywhere from a few kilometers to tens of kilometers. MANs connect LANs and BNs at different locations. Data is usually transmitted through leased lines or commercial services.
4. Wide Area Network (WAN)
-Can range anywhere from a few hundred kilometers to thousands of kilometers. Data is transmitted the same way mentioned in MANs, through leased lines or commercial services.
Internets and Extranets
Internet
-The internet is a network made up of networks
-It is worldwide
-Publicly Accessible
Intranet
-A website or other app that is only accessible by the internal users of a network
Extranet
-Provides controlled access to corporate websites and apps usually provided to select individuals.
Note: Internet, intranet, and extranet all share the same network model and protocols.
Network Models
Two of the most important network models are:
-Open System Interconnection Model (OSI Model)
-Internet Model
OSI 7 Layer Model:
7. Application Layer-Provides a set of protocols used by programs on the network.
6. Presentation Layer-Prepares data for the user, uses data to provide an interface, data compression and translates between different formats.
5. Session Layer-Starts, keeps, and ends sessions between the sender and the receiver.
4. Transport Layer-Prepares messages for transport throughout the network. Keeps the connection established between the message sender and the message receiver.
3. Network Layer-Makes routing decisions.
2. Data Link Layer-Identifies the beginning and end of a message (called message delineation), checks messages for errors, and network medium access control.
1. Physical Layer-Defines how bits are formatted to actually be transmitted through the network.
The Internet 5 Layer Model:
5. Application Layer-The application layer is used by apps.
4. Transport Layer-Establishes connections. The transport layer translates domain names into its corresponding numeric address and breaks larger messages into smaller messages.
3. Network Layer-Makes routing decisions.
2. Data Link Layer-Identifies the beginning and end of a message (called message delineation), checks messages for errors, and network medium access control.
1. Physical Layer-Defines how bits are formatted to actually be transmitted through the network.
What is a protocol?
A protocol is a set of rules that decides how to communicate with each layer and how to interface with adjacent layers.
Networking Example:
-Clicking a link starts an HTTP request-response cycle. Your browser now sends the HTTP request.
-HTTP request is now forwarded to the transport layer's TCP protocol. The HTTP request is then placed in a TCP segment.
-TCP segment then gets placed in a network layer packet, called the IP.
-The IP packet is then put into a data link layer frame. The TCP segment is sent over the network media access (such as fiber optic cables) as a series of 1's and 0's (physical layer).
Network Standards
Example of standards that are used in each layer:
Application Layer-HTTP, WAP, RTSP, H.323, FTP, SMTP, IMAP, POP
Transport Layer-TCP, SPX
Network Layer-IP, IPX
Data Link Layer-Ethernet, PPP
Physical Layer-Cat 5 Twisted Pair Cables (LAN), V.92 (56 Kbps Modem)
Standard Making Bodies
-International Organization for Standardization (ISO)
-International Telecommunications Union-Telecom Group (ITU-T)
-American National Standards Institute (ANSI)
-Institute of Electrical and Electronic Engineers, Standards Association (IEEE-SA)
-International Engineering Task Force (IETF)
NOTE: THIS TUTORIAL MAY BE REPRODUCED FREELY OVER THE INTERNET.
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