Intrusions from the Unknown: Importance of Network Security in Today's Environment and Security Issues Associated with Networks.

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Intrusions from the Unknown:  Importance of Network Security in Today’s Environment and Security Issues Associated with Networks.

A network can be defined as “A group of two or more  linked together”. The main reason for doing this is to enable any 2 or more computers to share each other’s resources and thus this is a feature of all networks. Security in this context can be defined as “the act of protecting information (data files) from being access by unauthorised individuals or groups”. There are three common types of network set up which are defined by there topology. Figure 1 illustrates the difference between Star, Bus and Ring networks which are used in network types as LAN, WAN, WLAN etc. A network runs on protocols, which define a common set of rules and signals that computers on the network use to communicate. A network can be isolated and independent such as a small home-area network (HAN) but once a network is connected to another network it can be defined as an Internet. Networks are frequently thought of as two different systems due to the fact that they can be access internally as well externally. Both methods give rise to different security issues and should be tackled differently by the network administration.  

        Internal users in most cases are over looked as threats to security as they can cause malicious and unintentional damage to a network. Internal users have physical access to the network and there actions must be monitored closely. Physical security is vital and internal users should only be given access to parts of the network relevant to him / her. Rooms with important servers should be kept locked and only people with permission should be allowed to enter them. This measure may help to protect against sabotage by preventing physical harm to important components of the network such as servers and routers. If information is highly sensitive or essential for a business to operate hiring security guards may even be necessary to ensure that the physical framework of the network is not tempered with. Unintentional damage can also be caused by users normally lacking in basic knowledge of the workings of the network. Such an examples include data being accidentally deleted, clicking of dangerous e-mail attachments, accidentally giving away confidential information etc.  

Any network such as a LAN, WAN or WLAN has to transmit data, as this is one of the primary objectives of a network. Therefore steps must be taken to ensure that the transmission medium is secure. If this is not ensured data is liable to being to such activities like line tapping and line monitoring. This is an example of internal security being attacked and can be thought of as a physical attack on the network. Situations can occur where data transmission takes place over a public, non-secure facility and thus has to be secured. Preventing line tapping can be done by inspecting wires that carry data (especially terminal wires and telephone lines used for modems) for physical damage and the use of shielded cabling would make cables harder to tap. Line tapping cannot be detected at lower levels of the ISO OSI model (physical and link layers) thus detection and prevention must be carried out higher up in the model.

Encrypting data can also help solve this problem as it is encoded by the transmitter and can only be decoded by the recipient. There are two techniques to encrypt data, which is manual and automated encryption. Examples of manual encryption would be the Caesar Cipher technique and the Checkerboard technique while automated encryption is based on complex algorithms. Caesar Cipher is a simple technique but many electronic devices continuously alternate displacement of the plain text, which can produce very complex encrypted code. A simple example of the Caesar Cipher would be taking the word “NETWORKING” and displacing the letters by 3, which would give you “PGVYQTMKPI”. Trained cryptanalysts could break complex code and no code in theory is unbreakable but it may take a large amount of time to decipher. When the code is finally broken the information maybe be out of date for the purpose it was collected for.

        Wireless networks are forever on the increase and new measures have to be taken to protect the data. As there are no cables data is passed in the air so to speak and is prone to different kinds of attacks compared to traditional networks. A simple jamming transmitter can make communications impossible could be some distance from the actual physical network. As data on a Wireless networks is sent over the air, it can extend over the physical boundary of a network. This would make is liable for a hacker to tap the information without even entering the building depending on how strong the signal was. The only real way around this would to encode / encrypt that data so if it was intercepted it would have to be decoded first which is often a difficult task.

Viruses also pose a huge threat to network security and can cause massive amounts of data damage. A virus can be defined as a “program that infects an executable file without the users knowledge. After infection, the executable file functions in a different way than before”. Viruses can do a range of things such as display annoying messages to the user or even destroy all the data on a computer hard drive. By and large they are sent from external sources but I would class it as an internal problem because most attempts by an external source could be avoiding by simply educating the users of the network. There are many different types, which are characterised by their properties.                            

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        Preventing of viruses on a network is of up most importance as they can cause massive damage and open up a network to a whole variety of attacks. Anti virus programs and hardware have been developed to combat viruses. They work by searching for evidence of a virus program (by checking for appearances or behaviour that are characteristic of computer viruses), then finds infected files, and thus remove the virus. It is not enough just to purchase anti-virus software because it must be configured to protect all parts of the system and the best anti-virus software covers the day to ...

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