Contact Us Today 01642 716680

Intrusion Detection System

Definition: An Intrusion Detection System (IDS) is hardware or software that monitors network or system activities for malicious activities or policy violations and reports them to a management station.

In the field of cyber security, an Intrusion Detection System (IDS) is crucial for the timely detection of potential threats. By analysing network traffic or system events, IDS can identify suspicious behaviour that may indicate a breach or an attempt at unauthorised system access. Depending on the type of IDS employed, it can monitor for known attack patterns (signature-based Intrusion Detection System) or anomalous activity that deviates from regular user behaviour (anomaly-based IDS). Versions of IDS include Network-based Intrusion Detection Systems (NIDS), which monitor network traffic, and Host-based Intrusion Detection Systems (HIDS), which monitor operating system files and logs.

The function of Intrusion Detection System is not to prevent intrusion, which is instead the role of an Intrusion Prevention System (IPS), but to alert administrators and infosec professionals to potential threats so that they can take action. The importance of IDS in the context of cyber security lies in its ability to provide real-time analysis and reporting of possible threats, thereby allowing the organisation to respond before any significant damage occurs. Many IDS also have the capability to perform some automatic response actions to help minimise damage or delay the attacker until a manual intervention is possible.

Key Characteristics:

  • Monitoring: Continuous monitoring of network or system activities.
  • Detection: Identifies known and unknown threats by analysing patterns or anomalies.
  • Alerting: Notifies the appropriate personnel or systems when a potential security threat is detected.
  • Analysis: Can provide detailed information about the detected events to aid in response and remediation.


  • Real-World Example: A company’s network IDS detects unusual outbound traffic at an odd hour, which on further investigation turns out to be the transmission of confidential data by an infected host, indicating a data breach.
  • Hypothetical Scenario: An anomaly-based IDS observes that a system is making repeated login attempts to various internal servers. Since this is a deviation from the standard user behaviour profile, the IDS raises an alert that may indicate a potential brute force attack within the network.

Related Terms:

  • Exploit: An IDS may detect activities related to exploits, which are attacks on network vulnerabilities.
  • Vulnerability: IDS can alert administrators to potential exploitations of system vulnerabilities.
  • Brute Force Attack: IDS often detect brute force attack attempts by monitoring for repeated login failures.
  • Advanced Persistent Threat (APT): IDS can be vital in the early detection of APTs, as these threats often involve long-term network intrusion.

What is the OWASP Top 10: Download our flash cards to find out.

Inside you will find a description of the most common web vulnerabilities.

Contact us

Get a free, no obligation quote from one of our expert staff.