IDS vs. IPS: What’s the Difference?

Enforcing multi-layered defense systems, such as an intrusion detection system (IDS) and an intrusion prevention system (IPS), is one-way businesses reduce their susceptibility to cyberattacks.

According to a recent study by IBM, the average global cost of a data breach in 2024 reached $4.88 million [1]. By 2025, Cybersecurity Ventures estimates cybercrime costs to surpass $10 trillion, a significant increase from the $3 trillion recorded in 2015 [2].

Read on to learn more about the inner workings of IDS and IPS, including the differences between the two.

What is IDS?  

An intrusion detection system works passively by constantly monitoring cybersecurity threats within an organization. An IDS will trigger alerts if it detects potential network intrusion, prompting internal security teams to investigate and address the situation.

Types of IDS 

Each type of IDS is designed to address specific aspects of network security. The following list comprises different types of IDSs based on the location of deployment: 

• Network-based IDS (NIDS): Strategically positioned at key junctures within a network, an NIDS monitors inbound and outbound traffic for all devices connected to the network.

• Host-based IDS (HIDS): Installed on all endpoint devices with internet and internal network access, a HIDS can spot unusual internal network packets and identify malicious traffic that a NIDS might miss.

• Signature-based IDS (SIDS): This detection works by accessing a pre-programmed list of known threats and uses that information to flag suspicious behavior.

• Anomaly-based IDS (AIDS): This type typically uses machine learning to establish a baseline against which to compare abnormal behavior, such as a user attempting to log in during non-business hours.

Read more: What Is Cybersecurity? Definition + Industry Guide

What is IPS?

An intrusion prevention system (IPS) takes cybersecurity defense a step further. Like an IDS, it proactively monitors network traffic and host behaviors to identify anomalies or potential threats. However, what sets an IPS apart is its active defense mechanism. Upon identifying a potential threat, an IPS raises an alert and takes immediate action to block or mitigate the threat.

Types of IPS 

Based on the place of operation and type of defense strategy, an IPS can fall under the following categories: 

• Network-based IPS (NIPS): This monitors the entirety of an organization’s network traffic to detect any signs of suspicious activity.

• Host-based IPS (HIPS): Positioned on an endpoint like a laptop, HIPS focuses solely on the incoming and outgoing traffic generated by a particular device.

• Wireless IPS (WIPS): A WIPS detects and resolves unauthorized access attempts on Wi-Fi networks.

• Network behavior analysis (NBA): This type of IPS examines network traffic to pinpoint atypical traffic patterns linked to distributed denial of service (DDoS) attacks.

Threat scanning: An inside look at how IDS and IPS work 

An IDS and IPS may utilize one of the following three detection methods to fend off cyber threats: 

• Signature-based detection: Entails monitoring network packets and comparing them to a database of known attack signatures

• Statistical anomaly-based detection: Includes scanning network traffic, contrasting it with a predefined "normal" baseline to detect anomalies, including novel threats

• Stateful protocol-based detection: Helps firms identify protocol deviations by comparing observed events to predefined activity profiles that outline standard behavior

Learn more: What Is the Vulnerability Management Process and How Can You Use It?

IDS vs. IPS: Similarities and differences

IDS and IPS share notable similarities. Below is a list of the attributes that IPS and IDS have in common:

• Surveillance: Both solutions oversee networks, internet traffic, and activities across multiple devices and servers.

• Notifications: Both solutions alert you to potential threats or suspicious activity.

• Continuous learning: Depending on the detection system employed and machine learning, both IPS and IDS acquire the ability to identify anomalies and reduce false positives.

• Routine logging: Both systems maintain a record of monitored activities and actions taken, allowing you to trace an attack from start to finish.

Did you know? Security administrators often have the option to deactivate threat response features in IPS services, essentially transforming them into IDS.

While similarities exist, IDS and IPS aren’t interchangeable. Below is a  breakdown of the differences between IDS and IPS:

• Operation: An IDS halts at detection, allowing your discretion for action. Conversely, an IPS detects and takes action based on configured settings and policies to contain threats. 

• Downtime: Since IDS only alerts, it has no downtime, even during a false positive threat. However, an IPS might initiate automatic countermeasures when false positives occur. This could lead to disruptions in network connectivity or hindered access to certain resources.

Do IDS and IPS work together?

IPS and IDS can complement each other, providing a comprehensive security approach for your business. IPS actively monitors live traffic to safeguard network security, while IDS offers insights into network traffic patterns. Additionally, both technologies log attack and response data, enabling you to refine and reinforce your cyber defense strategies. 

You may also find security solutions that combine firewalls with IDS and IPS functionalities, commonly known as next-generation firewall (NGFW) or unified threat management (UTM).

NGFWs work to restrict network access and prevent intrusion. However, they aren't particularly effective at preventing attacks originating from within a network. IDS and IPS raise alerts for detected intrusions while also remaining vigilant for internal network attacks, adding to NGFW’s capabilities. Alongside IDS and IPS, an NGFW could incorporate traditional firewall technology coupled with deep packet inspection. 

Pros and cons of IDS and IPS

Let’s explore the advantages and disadvantages of implementing an IDS or IPS. 

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