1. McLean 20061 HIGHER COMPUTER NETWORKING Lesson 12 Network Security Requirements Description of computer and network security requirements (confidentiality, data integrity and availability). Description of threats to network security in terms of passive (monitoring of transmission) and active (modification of the data stream or the creation of a false stream) attacks.

2. McLean 20062 HIGHER COMPUTER NETWORKING What You Should Know About Security Requirements Computer and Network Security Requirements It is required by law (The Data Protection Act) that all data held about individuals must be protected from unauthorised access. Confidentiality - All network data must be kept confidential. This can be for commercial as well as security reasons. Data Integrity - All network data must be secure from corruption, data loss and has to be correct and up to date. Availability - All network data must be available to authorised users only, but on demand! Network security systems have to be effective but must also allow immediate authorised user access to data.

3. McLean 20063 HIGHER COMPUTER NETWORKING What You Should Know About Passive & Active Attacks Threats to network security are classified as Passive or Active Attacks. 1 Passive Attacks A passive attack is an attempt to intercept and copy network data. Hackers use programs to monitor the transmission of data travelling on the network, thus threatening the confidentiality of the data. Passive attacks often go unnoticed by authorised network users. The best method of defence against passive attacks is encryption.

4. McLean 20064 HIGHER COMPUTER NETWORKING What You Should Know About Passive & Active Attacks 2 Active Attacks An active attack is an attempt to damage or destroy network data. Hackers often modify the data stream of the network by diverting data through a computer system which corrupts the data before sending it on to it’s original destination. A similar method can be used which uses false data streams i.e. the data is diverted to a computer which replaces it with false data which is then sent on to the destination computer.