Security and Privacy in a Networked World/Networking

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NOTE: This topic makes use of Wikipedia articles to provide the basic understanding of the matters. These articles deal with technology and are not much disputed, having reached the common knowledge stage. They also provide some good links for further study under the reference sections.


Basics

The Internet as we know it today is actually not a single network but rather a mosaic of various networks that "speak the same language" in the TCP/IP protocol. It connects very different computers with very different purposes and services, yet the common principle is packet switching - the information sent over the network is divided into units called packets which are sent towards the destination independently. In case of a "roadblock" (e.g. a part of network has failed) tha packets are re-sent over different routes until they reach the destination.

Of networking hardware, the following are more important to the users:

  • Network interface (NIC) - commonly known as the "network card", the device that allows a computer to connect to networks (there are different interfaces for different types of networks). Most today's computers have at least one NIC for Internet connection, mobile devices (Laptops, tablets, smartphones) typically have a wireless network interface. NICs are identified by MAC addresses.
  • Hub - in simple terms, it is a connection box for multiple network cables, forming what is called a network segment. Hubs typically also act as repeaters - devices that clean the signal from noise and amplify it.
  • Switch can be (with some simplification) thought as a hub with "traffic cop skills" - it can filter and direct traffic between different NICs based on their MAC addressses.
  • Bridge - a device to connect different networks or their segments.
  • Router - a device that forwards packets between networks. Today, many home networks use routers between the local network at home and the larger network of the service provider.


Addressing in IPv4


Typical network settings in workstations/laptops

Today, most ordinary users connect to Internet via either broadband DSL or cable networks, or via various wireless networks. Earlier technologies having fallen out of use include dial-up and ISDN connections.

Most connections are made using the DHCP protocol which obtains the connection data automatically from a server - thus the computer user does not need to set up anything in order to connect. However, in some places, static connections are used that need the following data to be entered:

  • IP
  • netmask
  • gateway
  • name server

...

Network security: some things to consider

  • turn off everything not in use (especially server systems)
  • switch network off when not in use
  • In case of home WiFi (also for office systems meant for internal use), change the default name of the network to something unassuming and use the WPA2 encryption with good passwords. Providing a free WiFi service for e.g. guests is a good idea, provided that it is properly managed - a "fire and forget" WiFi may however result in a lot of trouble.

...

Additional reading and links

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