6 Types of Intrusion Detection System

types of intrusion detection system

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In cybersecurity the need for robust defence mechanisms is paramount. 

One critical component of this cyber defence is the Intrusion Detection System (IDS). 

This article embarks on a journey through the intricacies of IDS, unveiling the diverse types of Intrusion Detection System and shedding light on the vital role each plays. 

As well as explaining the differences of an IDS compared to a firewall and how an IPS differs to that of an IDS.

Understanding the nuances of these six distinct types of Intrusion Detection Systems becomes pivotal for organisations and individuals alike.

What is an Intrusion Detection System?

what is intrusion detection system

An Intrusion Detection System is a pivotal component within the cybersecurity architecture, functioning as a sophisticated surveillance mechanism designed to scrutinise and analyse network or system activities. 

Employing predefined algorithms, signatures, and behavioural patterns, an IDS adeptly detects anomalies or potential security threats in real-time.

An IDS monitors incoming and outgoing traffic to identify unauthorised access, malicious activities, or deviations from established norms. 

It provides a dynamic defence against cyber threats by generating alerts or notifications upon detecting suspicious patterns, enabling timely intervention.

How does an Intrusion Detection System work?

how intrusion detection system works

An Intrusion Detection System works through a meticulous process of continuous surveillance and analysis within the cybersecurity ecosystem. 

At its core, the IDS leverages sophisticated algorithms, predefined rules, and behavioural models to scrutinise network or system activities in real-time.

Upon deployment, the IDS meticulously examines data packets, analysing for deviations from expected patterns, signatures of known threats, or anomalies indicative of potential security breaches. 

This involves parsing through extensive datasets, analysing network traffic, and assessing system events with precision.

6 Types of Intrusion Detection System

6 types of intrusion detection system

The 6 main types of Intrusion Detection System are:

Host Intrusion Detection Systems (HIDS)

Host Intrusion Detection Systems operate as a defence on individual devices, focusing their analysis on  activities at the host level. 

Delving into the intricacies of system logs, file modifications, and user activities, HIDS provide a meticulous examination that yields granular insights into potential threats. 

By scrutinising the specific actions transpiring on a single device, HIDS contribute to a robust defence against localised intrusions.

Network Intrusion Detection Systems (NIDS)

Network Intrusion Detection Systems take a broader stance, analysing network traffic in real-time. 

Proficient in scanning for patterns indicative of malicious behaviour across the entire network, NIDS are adept at identifying attacks on a larger scale, covering multiple devices. 

By monitoring the flow of data between devices, NIDS provide a comprehensive and network-wide defence against potential threats.

Network Nodes Intrusion Detection Systems (NNIDS)

Network Nodes Intrusion Detection Systems extend the capabilities of NIDS by honing in on specific network nodes or devices. 

This focused approach allows for more targeted monitoring, enhancing the efficiency of threat detection. 

NNIDS offer a nuanced perspective, directing attention to individual nodes within the network, thereby providing a more tailored defence against potential intrusions.

Protocol Intrusion Detection Systems (PIDS)

Protocol Intrusion Detection Systems specialise in monitoring and analysing specific network protocols for suspicious activities. 

Tailored to analyse the intricacies of various communication protocols, PIDS provide a detailed examination that helps in identifying anomalies at the protocol level. 

By focusing on the intricacies of data exchange, PIDS contribute to a comprehensive defence against potential threats within the network.

Application Protocol Intrusion Detection Systems (APIDS)

Application Protocol Intrusion Detection Systems zoom in on the application layer protocols, delving deeper into the specifics of data interactions. 

This specialised focus allows for a more nuanced detection of potential threats at the application level. 

APIDS contribute to a refined defence mechanism and involve the intricacies of application-layer data exchanges, providing an additional layer of protection.

Hybrid Intrusion Detection Systems

Hybrid Intrusion Detection Systems bring together the strengths of both HIDS and NIDS, offering a comprehensive approach to threat detection. 

By combining the localised focus of HIDS with the network-wide surveillance capabilities of NIDS, Hybrid IDS provide a robust defence against a spectrum of threats. 

This amalgamation ensures that potential intrusions are identified and addressed both at the individual device and network levels, offering a holistic and versatile cybersecurity solution.

3 Types of Intrusion Detection System Methods

3 types of intrusion detection system methods

While there is 6 types of Intrusion Detection System, each works within 3 main methods:

Signature-Based Intrusion Detection

Signature-Based Intrusion Detection relies on predefined patterns or signatures of known threats. 

It operates akin to a digital fingerprint sensor, where the system compares incoming data or activities against a database of known malicious signatures. 

When a match is detected, an alert is promptly triggered, signalling a potential intrusion. 

This method is effective against well-established threats with recognized patterns. 

However, it may struggle with detecting novel or modified attacks that deviate from known signatures.

Anomaly-Based Intrusion Detection

Anomaly-Based Intrusion Detection takes a more dynamic approach by establishing a baseline of normal behaviour within a system or network. 

It continuously monitors and learns the typical patterns of activities, such as network traffic, user behaviour, or system processes. 

Any deviation from this established baseline is flagged as a potential threat. 

Anomaly-based detection is effective in identifying previously unknown attacks or subtle variations in attack patterns. 

However, it may generate false positives if the system fails to distinguish between legitimate changes and actual threats.

Hybrid Intrusion Detection

Hybrid Intrusion Detection Systems seamlessly integrate the strengths of both signature-based and anomaly-based methods. 

By combining these approaches, Hybrid IDS offers a robust defence against a broad spectrum of threats, encompassing both known and unknown risks. 

The signature-based component provides a swift response to recognized threats, ensuring immediate action when familiar patterns emerge. 

Simultaneously, the anomaly-based component adds a layer of adaptability, capable of identifying novel or evolving threats by detecting deviations from normal behaviour. 

This amalgamation makes Hybrid IDS a versatile and comprehensive solution, leveraging the strengths of each method to enhance overall threat detection and response capabilities.

Why are Intrusion Detection Systems Needed?

why intrusion detection system needed

Intrusion Detection Systems stand as indispensable components in the cybersecurity landscape, fulfilling critical roles that fortify the digital defence infrastructure. 

Their necessity arises from their ability to detect potential threats in real-time and monitor network and system activities. 

This real-time detection capability allows organisations to swiftly identify and respond to unauthorised activities, mitigating risks before they escalate.

Moreover, IDS contribute significantly to risk mitigation by providing prompt responses to potential intrusions. 

Their ability to raise immediate alerts enables cybersecurity teams to take proactive measures, preventing or minimising the impact of security breaches. 

Additionally, IDS offer comprehensive insights into the nature and source of attacks, facilitating a deeper understanding of cybersecurity threats.

Common Ways to Avoid an Intrusion Detection System

common ways avoid intrusion detection system

While IDS are needed and are vital pieces of cybersecurity, they are not infallible. 

Criminals use a variety of methods to bypass an IDS, with the most common being:


The utilisation of encryption serves as a method to obfuscate potentially malicious activities, posing a challenge for Intrusion Detection Systems to discern unauthorised access or data breaches. 

By transforming data into an unreadable format that can only be deciphered with the appropriate decryption key, encryption becomes a potent tool in concealing sensitive information from the prying eyes of IDS.


Flooding the network with an overwhelming volume of traffic stands as a tactic to divert the attention of IDS. 

By inundating the system with an excess of data, the sheer magnitude can lead to a saturation point, potentially causing the IDS to overlook or miss crucial indicators of malicious activities. 

This flood-based approach aims to reduce the effectiveness of IDS by creating a chaotic environment that hampers its ability to distinguish genuine threats from the deluge of data.


Breaking down malicious activities into smaller fragments forms a strategy to evade detection by IDS. 

As the system processes information in fragments, piecing together the complete picture of an attack becomes more challenging. 

This fragmentation tactic aims to exploit the difficulty IDS may encounter in assembling disparate data fragments to comprehend the entire scope of a potential intrusion.


The employment of obfuscation techniques, such as disguising malicious code or altering its appearance, introduces an additional layer of complexity for IDS. 

By making it harder for IDS to recognize and interpret threats, obfuscation becomes a method of choice for those seeking to evade detection. 

This technique involves camouflaging the true nature of malicious activities, making it challenging for IDS to accurately identify and respond to security threats.

How are Intrusion Detection Systems and Firewalls Different?

intrusion detection system vs firewall

Although both Intrusion Detection Systems and Firewalls play integral roles in bolstering network security, their functionalities diverge. 

A Firewall operates as a proactive barrier, managing incoming and outgoing network traffic according to predefined security rules. 

This preventive measure aims to establish a secure perimeter by allowing or blocking data packets based on established criteria.

On the other hand, an Intrusion Detection System takes on a more vigilant role within the network security landscape. 

Instead of solely focusing on traffic regulation, IDS actively monitors and detects potential threats within the network. 

It serves as a reactive mechanism, providing real-time alerts and comprehensive insights into suspicious activities that may indicate unauthorised access or potential security breaches. 

While Firewalls emphasise access control and traffic management, IDS prioritises the identification and response to anomalies or malicious activities occurring within the network. 

How are Intrusion Detection Systems and Intrusion Prevention Systems Different?

intrusion-detection system vs intrusion prevention system

Intrusion Detection Systems and Intrusion Prevention Systems share common ground but differ in their actions. 

An IDS focuses on detecting and alerting about potential threats within a network. 

It provides real-time insights into suspicious activities, enabling cybersecurity teams to respond promptly.

In contrast, an IPS takes a more proactive stance by not just identifying threats but also implementing automatic measures to prevent them. 

IPS can autonomously respond to detected threats by blocking or mitigating their impact, offering a hands-on approach to cybersecurity. 

This distinction means that while IDS is primarily an observer and reporter, IPS takes direct action to thwart potential threats before they can manifest, contributing to a more dynamic and preemptive defence against evolving


The world of cybersecurity relies heavily on Intrusion Detection Systems to safeguard digital assets and maintain the integrity of networks and systems. 

Understanding the different types of Intrusion Detection Systems, and the critical role of IDS provides a foundation for creating robust defence mechanisms against the ever-evolving landscape of cyber threats. 

With the continuous evolution of digital threats, the role of IDS remains pivotal in ensuring a secure and resilient cyberspace.

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