Introduction to Firewalls
- A firewall is a computer or group of computers that stand between trusted networks (such as LAN) and untrusted networks (such as the Internet), inspecting all traffic passing between them.
- A firewall can be a router, a personal computer, or a collection of hosts, that is set up specifically to shield a private network from security attacks that comes from an external entity.
- The basic function of a firewall is to screen network traffic for the purpose of preventing unauthorised access between computer networks.
- To be effective in their operation, firewalls must have the following attributes:
- All communications must pass through the firewall
- The firewall permits only traffic that is authorized
- The firewalls can withstand attacks upon itself
