Describe the roles of firewalls, intrusion detection systems, and antivirus software in
promoting security.
Firewalls prevent unauthorized users from accessing internal networks. They protect internal systems by monitoring packets for the wrong source or destination, or by offering a proxy server with no access to the internal documents and systems, or by restricting the types of messages that get through, for example, email. Further, many authentication controls have been added for Web pages as part of firewalls.
2) Intrusion detection systems monitor the most vulnerable points in a network to detect and deter unauthorized intruders. These systems often also monitor events as they happen to look for security attacks in progress. Sometimes they can even be programmed to shut down a particularly sensitive part of a network if it receives unauthorized traffic.