What is an Intrusion Detection System (IDS)? In-Depth Guide

By Tibor Moes / Updated: June 2023

What is an Intrusion Detection System (IDS)? In-Depth Guide

What is an Intrusion Detection System (IDS)?

In the ever-evolving digital landscape, securing networks and data from potential threats has never been more crucial. What is an intrusion detection system (IDS)? It plays a vital role in safeguarding sensitive information and maintaining robust network security. So, how can an IDS help your organization stay ahead of the curve? Let’s dive in and explore the world of intrusion detection systems.


  • Intrusion Detection Systems (IDS) monitor network traffic for malicious activity, with two primary techniques: signature-based and anomaly-based detection.

  • The advantages of implementing an IDS include enhanced security, faster incident identification, and improved compliance.

  • Complementary Security Technologies such as IPS and Firewalls work together to protect networks from threats. Selecting the right IDS solution requires assessing your organization’s needs.

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Understanding Intrusion Detection Systems (IDS)

An Intrusion Detection System (IDS) is a powerful tool designed to monitor network and technology systems for suspicious activity or known threats. Its primary purpose is to keep an eye on network assets, detecting and alerting security professionals to any potential issues. IDS come in many forms. These include network-based, host-based, protocol-based, and application protocol-based, as well as hybrid types. These systems can be deployed as a software application on your hardware, a network security appliance, or even as a cloud-based solution.

IDS works by analyzing network packets, identifying network hosts and devices, and inspecting data within those packets to determine the operating systems and services being used. By constantly monitoring network traffic, IDS can identify security incidents, generate alerts, and help security professionals mitigate risks and protect data.

IDS Deployment: Network-Based vs. Host-Based

When it comes to deploying an IDS, there are two main options: network-based and host-based. Each has its own set of advantages and disadvantages, so choosing the right one for your organization depends on your specific needs and requirements.

In the following sections, we’ll explore the differences between these two types of IDS deployment.

Network-Based IDS

A Network-Based Intrusion Detection System (NIDS) is a type of software that monitors network traffic and detects security issues or malicious activity. By keeping an eye on the entire network, a network-based IDS can detect any malicious activity regardless of its source or destination. This means that it can catch threats that a host-based IDS might miss.

However, setting up and maintaining a network-based IDS can be challenging, as it may generate false positives and struggle to detect malicious activity that is hidden or encrypted. Despite these challenges, a network-based IDS is often an essential component of a comprehensive security infrastructure, as it provides a broad view of your entire network and can effectively detect potential threats.

Host-Based IDS

In contrast to network-based IDS, a Host-Based Intrusion Detection System (HIDS) is installed on individual devices, monitoring the incoming and outgoing packets on each host. It excels at detecting malicious activity on the host itself, even if it’s not visible to a network-based IDS. This means that it can effectively identify threats regardless of their source or destination.

Much like its network-based counterpart, a host-based IDS can also be challenging to set up and maintain, and may produce false alarms. Furthermore, it may struggle to detect malicious activity that is encrypted or hidden.

Despite these drawbacks, implementing a host-based IDS can be a valuable addition to your security arsenal, as it provides an in-depth view of individual hosts within your network.

Key Detection Techniques in IDS

Intrusion Detection Systems employ two primary detection methods to identify malicious network traffic: signature-based detection and anomaly-based detection. Both techniques have their own strengths and weaknesses, and some IDS solutions even utilize a hybrid approach to maximize threat detection capabilities.

Let’s take a closer look at these key detection techniques.

Signature-Based Detection

Signature-based detection is a widely used technique that identifies malware and other malicious codes by comparing them to a database of known signatures. This approach is popular among antivirus programs and IDS alike. Signature-based IDS use fingerprints of known threats to detect malicious traffic or packets.

The main drawback of signature-based detection is its inability to identify new or unknown malicious network traffic. Since it relies on matching known patterns of malicious behavior, it cannot detect previously unknown attacks. This limitation has led to the development of alternative detection techniques, such as anomaly-based detection.

Anomaly-Based Detection

Anomaly-based detection is designed to identify known attack signatures as well as deviations from normal activity. It achieves this by using machine learning to compare incoming traffic with a trusted activity model. Anomaly-based detection can spot previously unknown threats, making it more reliable than signature-based detection and generating fewer false positives.

However, implementing anomaly-based detection can be challenging, as it often leads to a higher rate of false positives. Despite this hurdle, anomaly-based detection serves as a powerful tool in detecting previously unknown threats, making it a valuable addition to your organization’s security toolkit.

Advantages of Implementing an Intrusion Detection System

Investing in an Intrusion Detection System comes with a host of benefits that can significantly enhance your organization’s security posture. One of the key advantages is the ability to rapidly detect known anomalies, giving you greater insight into your network. This, in turn, helps reduce financial, business, and operational risks associated with security incidents.

Another major advantage of implementing an IDS is its ability to help your organization stay compliant with security regulations. By providing a deeper understanding of your network, an IDS makes it easier to adhere to these regulations, while also using IDS logs as evidence of compliance.

Ultimately, using an IDS can result in better overall security, faster incident identification, and improved compliance achievement.

Challenges Faced by Intrusion Detection Systems

Despite their numerous benefits, IDS solutions are not without their challenges. One of the most common issues faced by IDS is the occurrence of false positives – alerts generated by the system that turn out to be benign. These false alarms can be time-consuming for security professionals to investigate and may lead to valid traffic being blocked.

In addition to false positives, IDS may struggle to detect threats that employ obfuscation, encryption, or polymorphism techniques to evade detection. Furthermore, IDS are typically designed to identify known patterns of suspicious behavior, making it difficult to detect new malware that does not exhibit these patterns.

To overcome these challenges, organizations must continually update and fine-tune their IDS to ensure optimal performance in detecting both internal and external threats.

Complementary Security Technologies: IDS, IPS, and Firewalls

Intrusion Detection Systems, Intrusion Prevention Systems, and Firewalls are all security technologies that work together to protect networks and systems from malicious activity. While IDS monitor traffic and alert security professionals of potential threats, IPS provides control and protection, and firewalls actively prevent threats from becoming incidents.

Let’s delve deeper into the roles of IPS and firewalls in network security.

Intrusion Prevention Systems (IPS)

An Intrusion Prevention System (IPS) is a security system that monitors network traffic for malicious activity and blocks it if detected. Unlike IDS, which passively monitors traffic, IPS acts as an active protective device, providing control and protection against threats. IPS utilizes two methods for detecting attacks – signature-based detection and statistical anomaly-based detection. This allows them to accurately respond to malicious activity.

While the automated response of an IPS makes it more effective at safeguarding systems, it also comes with its own set of challenges. If the IPS is not configured correctly to match the network and application usage, it may not function properly, leading to false positives and blocking valid traffic.

Nevertheless, IPS solutions are a valuable addition to an organization’s security infrastructure.


Firewalls serve as a critical component of network security, acting as a barrier between a secure internal network and an untrusted outside network, such as the internet. They monitor and control the traffic entering and leaving a network based on predefined security rules, protecting networks from malicious traffic and unauthorized access.

Firewalls and IDS complement each other to provide a comprehensive security setup. While firewalls actively block malicious traffic, IDS detects and alerts you to any suspicious activity on the network. Together, firewalls, IDS, and IPS form a robust security infrastructure that helps safeguard your organization’s data and network from a wide range of threats.

Selecting the Right IDS Solution for Your Organization

Choosing the right IDS solution for your organization depends on your specific needs and requirements, which will vary based on factors such as the size and type of your organization, as well as the kind of data that needs to be protected. To evaluate different IDS solutions, consider factors like data collection requirements, performance, reliability, and placement of the IDS device.

Ultimately, the right IDS solution will depend on your organization’s unique circumstances and security goals. By thoroughly assessing your needs and carefully evaluating the available IDS solutions, you can ensure that you select the most effective intrusion detection system for your organization, providing robust protection against potential threats and enhancing your overall security posture.


In conclusion, Intrusion Detection Systems play a critical role in safeguarding networks from a wide array of potential threats. With various types of IDS deployments, detection techniques, and complementary security technologies, organizations can tailor their security infrastructure to meet their unique needs and requirements. Implementing an IDS not only enhances network security, but also helps organizations stay compliant with security regulations and reduce the risks associated with security incidents.

As the digital landscape continues to evolve, it is essential for organizations to stay one step ahead of potential threats. By selecting the right IDS solution and integrating it with complementary security technologies, you can ensure that your organization is well-equipped to face the challenges of today’s cybersecurity landscape, safeguarding your valuable data and maintaining robust network security.

How to stay safe online:

  • Practice Strong Password Hygiene: Use a unique and complex password for each account. A password manager can help generate and store them. In addition, enable two-factor authentication (2FA) whenever available.
  • Invest in Your Safety: Buying the best antivirus for Windows 11 is key for your online security. A high-quality antivirus like Norton, McAfee, or Bitdefender will safeguard your PC from various online threats, including malware, ransomware, and spyware.
  • Be Wary of Phishing Attempts: Be cautious when receiving suspicious communications that ask for personal information. Legitimate businesses will never ask for sensitive details via email or text. Before clicking on any links, ensure the sender's authenticity.
  • Stay Informed. We cover a wide range of cybersecurity topics on our blog. And there are several credible sources offering threat reports and recommendations, such as NIST, CISA, FBI, ENISA, Symantec, Verizon, Cisco, Crowdstrike, and many more.

Happy surfing!

Author: Tibor Moes

Author: Tibor Moes

Founder & Chief Editor at SoftwareLab

Tibor is a Dutch engineer and entrepreneur. He has tested security software since 2014.

Over the years, he has tested most of the best antivirus software for Windows, Mac, Android, and iOS, as well as many VPN providers.

He uses Norton to protect his devices, CyberGhost for his privacy, and Dashlane for his passwords.

This website is hosted on a Digital Ocean server via Cloudways and is built with DIVI on WordPress.

You can find him on LinkedIn or contact him here.

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