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Networks and Computer Security

You may consider being able to connect to the Internet through your computer, laptop or cellphone as a very common task today. However, this was not that easy around 25 years ago, when the first computers really started to communicate with other computers located anywhere else.

Networks

Two or more computers or devices interconnected form a network. This system usually shares resources, information, output devices and software.

Next is shown the Seven-layer model that specifies how data is sent and received over the network.

Application: Uses commands to tell the computer how to handle the data to be presented to the user.

Presentation: Converts from system-specific format to network format.

Session: Adds a header for managing sessions.

Transport: Breaks data into several pieces that will be put together by the receiving computer. Each piece is then sent to the network layer.

Network: The segments become packets and the source and destination is added.

Data Link: The packets become frames created for a specific network.

Physical: Puts the bits in a physical mean to be sent over.