IPS (Intrusion Prevention System) Symantec Sygate Enterprise Protection only. A device or software used to prevent intruders from accessing systems from malicious or suspicious activity. This is contrast to an Intrusion Detection System (IDS), which merely detects and notifies. Symantec Protection Agent is both an IDS and an IPS product since the Agent includes both an IDS and firewall functionality making it capable of not only detecting but also blocking an attack. See also Intrusion Detection System (IDS).