An intrusion prevention system (IPS) has the capability to both detect and prevent security breaches by taking active measures such as dropping malicious packets, blocking traffic from the offending IP addresses, or alerting administrators. While an intrusion detection system (IDS) and a firewall can both detect threats, neither takes automated actions to prevent them like an IPS does. A proxy server, on the other hand, is primarily used to control and filter outgoing and incoming network traffic between the user and the internet.