Networks operate on the principles of communication and sharing. Unfortunately, these principles mean that network traffic and data risk being accessed by people who have no authority to do so (ie hackers).

A network attack is an attempt to gain access to, steal, modify or delete data on a network. Such attacks take several forms:

• Active - where the hacker attempts to modify or delete data, or to prevent a network from operating correctly. An example of this is denial of service (DOS) attacks on the internet, which use many internet enabled computers to force a web server offline.
• Eavesdropping (passive) - where the hacker monitors a network in order to gain information. An example of this is wiretapping, where communications are monitored.
• External - where someone outside of an organisation attempts to hack its network.
• Internal - where someone within an organisation attempts to hack its network.

The number of network attacks is growing daily.