Network Intrusion Detection Systems: The Complete Guide

Network intrusion detection systems (NIDSs) are computer software capable of identifying and reporting various network problems – namely, those related to cybersecurity and data protection. While the broad concept of intrusion detection has existed for decades, in recent years, NIDSs have risen to additional prominence as a means of keeping networks safe from ever-evolving malicious activity, such as sophisticated data breaches and malware attacks.

Read on for an in-depth look at NIDSs, including the technology’s various uses and benefits, practical forms, and potential considerations for the future.

What Is A Network Intrusion Detection System?

NIDSs are an important component of modern cybersecurity infrastructure that help protect computer networks from unauthorized accesses, data breaches, and other nefarious actions.

But, specifically, what is an NIDS? In essence, NIDS systems are software applications that monitor network traffic and alert system administrators when they detect suspicious or abnormal behavior that could indicate an intrusion. NIDSs work by analyzing network packets in real-time and comparing them to a database of known attack signatures – or patterns of behavior associated with known cyber attacks. If a packet matches a known signature, the NIDS generates an alert to initiate an appropriate response, such as blocking the offending IP address or shutting down the affected system.

Additionally, many NIDSs also use behavioral analysis techniques that can identify abnormal traffic patterns, such as unusually high network activity or repeated attempts to access a particular resource. These techniques can be particularly useful in detecting so-called “zero-day” attacks, which are previously unknown exploits currently absent from a signature database.

NIDS systems have become essential because cyber threats constantly change to combat equally progressive data protection measures. Moreover, with the rise of cloud computing, the Internet of Things (IoT), and other advanced technologies, there are more opportunities for attackers to exploit vulnerabilities in network infrastructure. A single breach can have catastrophic consequences for a corporation, including the theft of sensitive data, the disruption of critical services, and the compromise of entire networks.

By providing real-time detection and alerting capabilities, NIDSs can help organizations respond quickly and effectively to potential security breaches. They also play an important role in compliance with industry regulations and standards, such as the Payment Card Industry Data Security Standard (PCI DSS) and the Health Insurance Portability and Accountability Act (HIPAA).

Benefits of Network Intrusion Detection Systems (NIDSs)

NIDSs provide multiple benefits rooted in network safety, integrity, and stability. These offerings include:

Real-Time Threat Detection

One of the primary benefits of NIDSs is their high-level, real-time detection of potential security breaches. This capability allows system administrators to respond quickly and effectively to minimize breach damage and prevent further attacks. By alerting administrators to potential breaches, NIDS can help organizations identify and isolate affected systems, implement patches or other security measures, and prevent further damage.

Compliance With Industry Standards

Many industries have specific regulations and standards that require organizations to implement security measures – such as an NIDS – to protect sensitive data. For example, the aforementioned PCI DSS requires organizations that process credit card transactions to implement intrusion detection systems to protect against data breaches. NIDSs are one of several ways organizations remain compliant in this manner.

Cost-Effective Security Solution

Compared to other security measures, such as hiring additional security personnel or implementing physical security measures, NIDSs are a relatively cost-effective solution. In most cases, NIDSs can provide continuous monitoring and threat detection without the need for additional personnel or resources.

Protection Against Zero-Day Attacks

Zero-day attacks are previously unknown exploits not yet listed in an organization’s signature database. NIDSs that use behavioral analysis techniques can detect abnormal traffic patterns that may indicate a zero-day attack, allowing organizations to take immediate action to mitigate the damage.

Network Visibility

NIDS systems provide organizations with greater visibility into their network traffic, allowing them to pinpoint potential security risks and optimize network performance. By analyzing network traffic, NIDS can highlight bottlenecks, monitor bandwidth usage, and detect potential security threats.


Another notable trait of NIDSs is their scalability, which allows them to meet the needs of organizations of nearly all sizes. Organizations can deploy an NIDS on individual systems or across entire networks, providing continuous monitoring and threat detection.

Centralized Management

Organizations can also centrally manage their NIDSs, giving administrators a single interface for monitoring and responding to potential security threats. This trait can simplify the management of security policies and improve the overall efficiency of incident response.

Reduced False Positives

NIDS that use behavioral analysis techniques can reduce the number of false positives generated by signature-based detection systems. By analyzing network traffic patterns and behavior, NIDS can identify and alert administrators to potential security threats that might go unnoticed by signature-based detection alone.

Continuous Monitoring

In providing continuous monitoring and threat detection, NIDSs help organizations avoid potential security threats. With the constantly evolving nature of cyber threats, continuous monitoring is essential for maintaining the security and integrity of computer networks.

Different Types of Network Intrusion Detection Systems (NIDSs)

There are several prominent NIDS types, each offering unique characteristics and benefits to an organization’s network. These categories include, but are not limited to:

Signature-Based NIDS

Signature-based NIDSs compare network traffic against a database of known attack signatures. When a signature matches the incoming traffic, the NIDS alerts system administrators.

Anomaly-Based NIDS

Similarly, an anomaly-based NIDS works by establishing a baseline of normal network traffic and comparing current traffic to that baseline. Any traffic that deviates from the established baseline is flagged as anomalous and triggers an alert.

Protocol-Based NIDS

This type of NIDS focuses on monitoring specific network protocols, such as hypertext transfer protocol (HTTP), file transfer protocol (FTP), or secure shell (SSH). Like their counterparts, protocol-based NIDSs can identify traffic that is not compliant with their set protocol, such as an FTP connection that is attempting to use a non-standard port or protocol.

Hybrid NIDS

Hybrid NIDSs combine signature-based and anomaly-based detection methods; they leverage the strengths of both methods to provide a more comprehensive detection system. Hybrid NIDS are effective at detecting known and unknown attacks while minimizing false positives.

Host-Based NIDS

Organizations often install host-based NIDSs on individual hosts or servers rather than on a network. Host-based NIDSs can detect attacks that are not visible at the network level, such as attacks that target specific software vulnerabilities. These systems are also useful for protecting individual hosts or servers and see use in conjunction with network-based NIDSs for comprehensive protection.

How Network Intrusion Detection Systems (NIDSs) Are Used

Organizations typically deploy NIDSs as an additional layer of security to complement other security measures, such as firewalls, anti-virus software, and access controls. Therefore, when it comes to introducing NIDSs into existing networks, administrators typically follow a series of well-established steps to ensure seamless integration and effective operation.

First, organizations must identify the areas of their network that require NIDS coverage; they typically accomplish this by conducting a thorough risk assessment, which involves identifying the types of assets, data, and network segments that require protection. Once these areas are known, organizations can proceed to selecting and configuring the appropriate NIDS software.

The next step involves configuring the NIDS software to work with the existing network infrastructure. This step usually entails setting up monitoring interfaces, such as network taps or span ports, to capture network traffic and direct it to the NIDS sensors for analysis. Organizations must also configure the NIDS sensors to analyze network traffic and detect potential intrusions based on pre-defined rules and policies.

Once the organization has successfully configured the NIDS software, it must test the system to ensure proper integration. Administrators should facilitate several assessments confirming this compatibility, including connectivity tests, stress tests, and intrusion detection tests. The organization might also conduct penetration testing to simulate real-world attack scenarios and identify weaknesses in the NIDS.

Following testing, administrators must ensure regular maintenance of the NIDS system to keep it up-to-date, functional, and safe. Auditing, in this sense, involves reviewing and updating the system’s rules and policies to keep pace with new threats and vulnerabilities – as well as monitoring the system for alerts and responding promptly to any detected intrusions or anomalies.

Potential Network Intrusion Detection Systems (NIDSs)


While they sport numerous benefits, modern NIDSs are still vulnerable to a range of potential threats, including evasion techniques that hackers and cybercriminals use to bypass detection. Such methods include, but are not limited to:

Encrypted Traffic

One of the most common ways hackers attack NIDSs is by encrypting their traffic. Encrypted traffic appears as an unintelligible stream of data to an NIDS, making it difficult to analyze. If the NIDS cannot decrypt and analyze encrypted traffic, a hacker could potentially use this method to evade detection.

Polymorphic Malware

Polymorphic malware is a type of malware that changes its code on each iteration, making it difficult for traditional signature-based detection methods to identify. If a hacker can create or obtain polymorphic malware, they may be able to bypass NIDSs that rely on signature-based detection.

Protocol Tunneling

Protocol tunneling is the process of encapsulating one protocol inside another. For example, a hacker might encapsulate a malicious payload inside an innocuous protocol like HTTP. If the NIDS fails to detect and analyze the inner protocol, the malicious payload may seamlessly reach its target.

If a hacker can evade detection, they can exploit vulnerabilities in an organization’s network and steal sensitive data. It is important, therefore, that organizations have a strong IDS that can detect and respond to potential threats in real-time. By leveraging multiple detection techniques, and monitoring logs, organizations can improve their security posture and protect against ever-changing breaches.


In today’s rapidly expanding digital environment, cyber threats have grown to become both widespread and increasingly complex. In turn, to protect the data and overall integrity of their networks, organizations must ensure that their digital infrastructure is equally expansive and layered. An NIDS is an effective way to manage network traffic, bolster cybersecurity, and ultimately keep an organization’s personnel and data safe. If your organization is in need of such a digital transformation, consider NIDS integration today. Reach out to our team for questions or more information!