1. 1 AQA ICT AS Level © Nelson Thornes 2008 1 Firewalls and Virus Checkers

2. 2 AQA ICT AS Level © Nelson Thornes 2008 2 Firewalls What does a firewall do? It checks the data coming into a computer system via the Internet against a set of rules or criteria, and only lets permitted material through. It also helps to prevent unauthorised access to computer networks.

3. 3 AQA ICT AS Level © Nelson Thornes 2008 3 They work by: Allowing all traffic unless it does not meet certain criteria. Allowing no traffic unless it meets certain criteria. Basic criteria could be: nature of the data source of the data Firewalls

4. 4 AQA ICT AS Level © Nelson Thornes 2008 4 Firewalls can be hardware or software Firewalls Hardware Software

5. 5 AQA ICT AS Level © Nelson Thornes 2008 5 Firewalls Firewall software is usually included as part of the operating system. Specialist firewall software can also be purchased, for example:

6. 6 AQA ICT AS Level © Nelson Thornes 2008 6 How can organisations prevent unauthorised access? A firewall can log all attempts to enter a private network. Multiple attempts may suggest unauthorised attempts. This warning would allow extra security to be put in place. An audit trail is a record that shows who has accessed an ICT system and what they have done. Avoid using the term hacking in an exam, as this is rather vague. Unauthorised access

7. 7 AQA ICT AS Level © Nelson Thornes 2008 7 Firewalls How does the firewall in your own institution work? How does your institution prevent access to unsuitable websites? How does your institution prevent unauthorised access?

8. 8 AQA ICT AS Level © Nelson Thornes 2008 8 Anti-virus software continually scans for viruses, including Trojans and Worms. It must be kept up-to-date, though, as new viruses appear all the time. Companies usually charge a subscription for updates. Virus Checkers

9. 9 AQA ICT AS Level © Nelson Thornes 2008 9 Anti-virus software maintains a database of known viruses. Incoming data files, through e-mail, downloads or removable media, are checked against the database. Suspicious files are deleted or put into a safe quarantined area for further investigation. Scheduled scans of all data files on the system can be done automatically. Virus definitions need to be kept up-to-date and software subscriptions include regular downloads of updates. Anti-virus software