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What is an Intrusion Detection System (IDS)?

By Tibor Moes / January 2023

What is an Intrusion Detection System (IDS)?

What is an Intrusion Detection System?

Many people don’t notice their network has been infiltrated until they find out crucial information is missing. At this point, it’s already too late. A hacker can wreak havoc with the data and use it for various malicious purposes.

The only way to prevent this is to receive timely notifications about unauthorized access. That’s where an Intrusion Detection System (IDS) comes into play. Let’s find out why this technology is critical for your platform’s safety and how it works.

Summary: Intrusion detection systems are applications that monitor network traffic. They enable you or your staff to recognize suspicious activity and document malicious components. The threats they look for can range from standard malware to phishing attacks with links that steal information. Once an intrusion detection system determines unauthorized entry, it alerts IT professionals and provides crucial information, so they can react with robust security tools.

Tip: Not everyone has the resources for an Intrusion Detection System. Luckily, modern antivirus software and VPN services can fulfill many of the tasks a corporate IDS performs. 

How Do Intrusion Prevention Systems Work?

Once an IDS collects data, it observes network traffic to match detected patterns to previous attacks. This method is also known as pattern correlation.

Configured correctly, intrusion detection software can determine quickly if strange activity can be considered a cyberattack. After recognizing malicious traffic, it has robust features that zero in on unauthorized attempts to access the network. Next, it alerts specified IT administrators or technicians.

This brings us to the primary role of this monitoring system – the alarms allow you to troubleshoot almost immediately. You can identify the source of the issue and tell your security team to eliminate any harmful agents.

Intrusion detection systems generally use three detection methods:

Signature Detection

A signature-based IDS examines log data and monitors network traffic before comparing the findings to attack patterns. The patterns are also referred to as sequences. They’re normally comprised of byte (malicious intrusion) sequences.

A signature-based IDS lets you accurately identify and address attacks from various sources.

Anomaly Detection

Unlike signature-based IDS, anomaly-based detection pinpoints unknown attacks, like new malware. It adapts the network to these threats on the go with robust machine learning. That’s why it’s also called the machine learning-based method.

An anomaly-based IDS helps create a safe cyber security environment by developing trustworthy activity baselines – trust models. After performing a network scan, they compare these models to new behavior to discover unknown attacks.

Anomaly detection usually works great, but it has several flaws. For instance, you can get false alarms because previously unknown legitimate activity can be deemed malicious.

To avoid this, always have your system security team double-check the alarms when anomaly detection picks up potentially abnormal behavior.

Hybrid Detection

If you want to elevate your intrusion detection systems, hybrid applications might be your best option. They dramatically increase the analysis scope, as they let you identify more problems.

A comprehensive system can bolster your threat detection because it understands more evasion techniques hackers use to trick standard programs. This way, your security systems are less likely to be distracted by normal incoming network traffic while an attack takes place.

Here are the most effective techniques you can use with a hybrid-based intrusion detection system:

· Proxying and spoofing – Hackers can mask the attack source with incorrectly configured proxy servers. They enable them to bounce attacks. If the attempts to access the network are bounced and spoofed by your server, detecting them is incredibly challenging, but hybrid recognition makes things easier.

· Avoiding defaults – Ports utilized by different protocols don’t always indicate to the protocols that they’re transported. For instance, a hacker may have reconfigured the protocols to use another port. In turn, the only way to detect them might be to use a hybrid IDS.

· Low-bandwidth attacks – These refer to coordinated scans between several attackers or the allocation of hosts or ports to multiple hackers. This can prevent a standard IDS from recognizing captured packets as intrusion attempts. A hybrid platform may be necessary.

· Fragmentation – Fragmented packets enable attackers to remain hidden and bypass the system’s detection. The risk is dramatically reduced if you set up a hybrid IDS.

What Are the Different Types of Intrusion Detection Systems?  

While all intrusion detection systems have many things in common, not every prevention system is the same. These network security solutions are categorized into five groups:

Network Intrusion Detection System

A network intrusion detection system might be the most common detection system. It’s configured at a strategic point within your network to analyze inbound and outbound traffic from all connected devices.

This detection method observes passing traffic and matches it to known attacks. Once it determines unusual activity, it alerts the administrator.

There are numerous network intrusion detection systems. For instance, many firewall providers install it to their subnet to discover known attacks in a timely fashion.

Host Intrusion Detection Systems

A host intrusion detection system is generally incorporated into independent devices or hosts on your network. It assesses outgoing and incoming network traffic to help protect your network. This technology alerts your system security team if it recognizes malicious or suspicious activity.

The method works by comparing existing system files to previously taken snapshots of the network. If analytical items were deleted or edited, the application instructs the administrator to get to the bottom of the issue.

Organizations generally use this detection type to scan their entire network when maintaining mission-critical machines. These rarely change their layouts, so even the slightest modification is a red flag.

Protocol-Based Intrusion Detection Systems

Protocol-based intrusion detection systems involve an agent or system that constantly resides at the server’s front end. It controls and interprets protocols between users and the server. The technology aims to secure the network by monitoring the stream and accepting related HTTP protocols.

When scouring the entire network for malicious activity, this system can perform the so-called stateful protocol analysis. It examines the current state of the server and compares it to acceptable actions. If it recognizes any deviations, it notifies administrators and can recommend several ways to address the detected patterns.

Application Protocol-Based Intrusion Detection Systems

Application protocol-based detection systems are agents or systems that usually reside within groups of servers. They examine and interpret the communications of application-specific protocols to identify potential intrusions.

For instance, it can analyze the middleware of SQL servers because it communicates with the server’s central database. Any strange activity is sent to the administrator for further inspection.

Hybrid Intrusion Detection Systems

Developers can create a hybrid prevention system by combining at least two approaches or applications. If you opt for this method, your system or host agent information is mixed with network data. This way, you get a full picture of your network traffic.

In most cases, hybrid detection is better than other techniques. It relies on several advanced techniques to broaden the scope of analysis and uncover more threats.

What Are the Benefits of IDS?

There are many reasons you should enhance your platform with an intrusion detection system:

Higher System Security Through Improved Anomaly Detection

You can take your cyber security to new heights by integrating with an IDS. It lets you protect your sensitive information from suspicious traffic by recognizing potential malicious actors on time.

Once you install this technology, transferring network data will be much safer. You’ll be able to safeguard against even the most sophisticated attacks.

Just make sure your system is set up properly. Any mistake can be a perfect entry point for hackers.

Seamless Network Data Organization

Surprising as it may sound, intrusion detection doesn’t just improve safety with high-quality security information. It can also help you organize your data.

Think about it – a ton of data is processed through your network every day through various operations. Much of it is unnecessary, so you could use some technology to weed it out. And that technology is intrusion detection.

By distinguishing critical safety data from irrelevant information, you can save time by focusing on the right aspects of your business from the get-go. There’s no need to comb through endless system logs to trace back crucial data. Instead, everything is right in front of you, thanks to timely detection.

Helps You Stay Compliant

Having detailed network visibility through your IDS also lets you demonstrate your compliance.

After all, these prevention systems are placed at a strategic point to organize, examine, and alert you of suspicious traffic. It provides an in-depth view of your network to help determine whether you’re compliant. This minimizes the risk of legal trouble.

Nipping Threats in the Bud

An intrusion prevention system filters through your traffic flow to save time, resources, and energy. As it completes its search, it can identify some threats before they cause significant damage. Accordingly, you can take proper action to eliminate them and preserve your reputation.

The more threats your IDS recognizes and understands, the more it adapts to sophisticated attacks. The system evolves and reduces the chances of data theft.

Qualifying and Quantifying Attacks

Users rely on their IDS systems because they analyze the types and amounts of attacks by performing an in-depth quantitative and qualitative examination. Administrators can use this information to alter security systems and implement new, more effective technologies.

The data is also utilized to solve device configuration issues and identify bugs. Assessing future risks is much easier with such comprehensive information readily available.

Limitations of IDS

Even though IDS applications drastically optimize cyber security, they’re not omnipotent. Here are their limitations:

They Can’t Prevent Hackers on Their Own

The biggest limitation of an IDS is that it can’t prevent or block attacks. It merely helps uncover a suspected intrusion.

Therefore, you shouldn’t rely on your intrusion detection only. You should integrate it into a broad security network that consists of other measures and a team that knows how to implement them correctly.

Experienced Engineering Is Required

IDSs are incredibly helpful for monitoring your network, but their utility hinges on what you can do with the data they provide you with. As they don’t resolve or block issues, they can’t improve security if you don’t have trained personnel and policies to administer appropriate measures.

Inability to Analyze Encrypted Packets

IDS platforms can’t examine encrypted packets. Consequently, intruders can use these vessels to make their way to your network. Only when they’re deep into your system will an IDS register them, jeopardizing crucial information.

Minimal Ability to React to Fake IP Packets

Information from IP packets can be picked up by your IP, but the attacker can fake the address. In this case, the threat is more complex and harder to detect.

Frequent False Positives

Intrusion prevention systems often alert administrators to so-called false positives. In fact, they can be more prevalent than real threats.

You can tune your IDS to lower the number of false alarms, but your security experts will still need to respond to them. This provides real attacks with a window to slip through unnoticed.

Signature Library Updates Are a Must

The value of your IDS rests on the signature library that needs to be updated regularly. Otherwise, the system can’t recognize and inform you of the most recent attacks.

This makes intrusions from unknown sources a major problem. Your network is vulnerable until you add a new threat to the database.

Examples of IDS

The importance of a well-made IDS system can’t be overlooked. They allow you to shield important operating system files and other data with minimal effort.

However, some prevention systems are better than others. Here are your best options:


SolarWinds is an event management system that integrates real-time logs throughout your security infrastructure. This feature enables the program to function as both your host-based and network intrusion solution. It lets you discover a wide range of malicious activities and keeps your network safe from harm.

The platform is also a hybrid detector, combining anomaly-based and signature-based methods. It compares customizable rules to traffic sequences and can tell you what parts of your network are vulnerable.

Another impressive feature of this alerting system is that it has robust templates. These enable you to choose from default intrusion detection and set up your rules from scratch with an intuitive builder.

Furthermore, the intrusion prevention system helps organize sequence comparisons and pattern correlations. It lists them by associated category or alphabetically. Plus, you can view your historical activity, search for keywords, and filter through your rules to enhance the quest for threats.

The platform can develop thorough assessment reports with reporting or customizable templates. These are built into your interface and let you compile reports without a hitch. The actions help you audit your business, demonstrate compliance, and perform other essential duties.

Apart from reports, SolarWinds also has terrific capabilities for detecting and responding to suspicious activity. The list includes the following features:

· Logging off connected users

· Deactivating user accounts

· Terminating processes

· Detaching USBs and other network devices

· Blocking the affected IP address

You can use SolarWinds on all major operating systems, including iOS, Windows, and Linux.


McAfee is an exceptional prevention system that introduces real-time malware awareness to your virtual and physical network. It’s a signature-based platform that detects anomalies and uses dependable emulation methods to spot malicious actors. The app also correlates threats with your app usage to prevent future issues caused by cyberattacks.

The system gathers traffic from routers and switches before inspecting it with SSL decryption. This process allows McAfee to block threats on your on-premises and cloud-based platforms. The program utilizes central management to isolate hosts, limit connections, enact correlations to known attacks, and run other useful actions to manage its extraordinary visibility.

The greatest benefit of McAfee is high integrability and scalability. In other words, you can easily complement the system with other programs and increase the virtual workload.


Blumira is another event management system that detects threats and responds to them throughout your cloud storage. It continuously monitors your infrastructure for misconfigurations and unusual activity to prevent compliance breaches and data leaks.

The program provides high-quality matched data to simplify the investigation process. You can examine events on your entire network with Blumira and sift through them to prioritize alerts. Accordingly, the app lets you tackle the most urgent threats first before they compromise your business.

Blumira users also enjoy the ability to assign first responders. This means you can designate some of your staff to react to alerts immediately and address them early on.

In addition, the system can help you build customizable detection reports. You can automate them with excellent features by scheduling your reports, running them periodically, and saving them for later use. All these functions are available on an intuitive interface.


If you need an open-source intrusion system, Suricata is one of your best options. It operates on a coded platform and determines suspicious behavior with signature-based techniques. The result is real-time reporting on abnormal behavior, allowing you to counteract it.

The developers designed Suricata to process large amounts of traffic and detect protocols automatically. It’s also an effective packet sniffer, scouring each batch for unusual behavior to discover malformed code. Plus, the platform relies on machine learning, rule profiling, and protocol keywords to fend off cyber attackers.

The only downside is the lack of critical documentation features. This can hinder troubleshooting, as it can keep you from referencing the past to prepare for future events.

Nevertheless, it’s a trusted, easy-to-use detection platform.

Cisco Stealth Watch

This is an enterprise host-based and network intrusion detection system for macOS, Linux, and Windows devices. It uses agentless technology, which lets the platform meet the growing needs of your business environment. This impressive scalability allows you to prepare for a wider variety of threats through dependable prevention methods.

Cisco Stealthwatch utilizes intrusion recognition and response with entity monitoring. It establishes acceptable behavior baselines with streamlined machine learning.

The platform also applies an in-depth approach to visibility to ensure a clear overview of all network endpoints, data centers, and cloud-hosted services. It correlates suspicious activity or anomalies to timely service alerts, so you can address them quickly.

On top of that, the program can detect malware, even if it’s in an encrypted network, without decrypting it. You can use this feature to stay compliant when analyzing systems with private data.

Besides tremendous security advantages, Cisco Stealthware contextualizes intrusion recognition information with key data. It includes the user, place, application, and time of the attempt. This provides extensive knowledge about your threat, allowing you to dissect the data.

How Do You Set Up Your IDS?

After determining the type of IDS you need, it’s time to roll out your platform. The following best practices will help you do so adequately:

Train Your Staff and Establish Baselines

Training your team is imperative, as it helps make sure your staff has an in-depth understanding of the IDS and its role.

You also need to maximize the system’s efficiency through baselines. This part is especially tricky because each network carries different traffic. You need to define what can and can’t go through, so your IDS can react properly.

Deploy and Tune the IDS

Your IDS should be placed where it has the highest visibility of the network without overwhelming it with data. In most cases, this is at the edges of your system (behind firewalls).

Once it’s active, don’t forget to change your default settings. However, don’t change every setting – only make tweaks that make sense.

Also, configure your platform to accommodate security points, protocols, ports, applications, and devices. You’ll help set up a sold detection base.

Test the System

Test your IDS to make sure it recognizes threats and addresses them correctly. You could have a security professional perform a penetration test. They give you insights into the system’s operation and whether you need to adjust the platform.

Balance False Negatives and False Positives  

Too many false negatives and false positives can overburden your network. To avoid this, consider segmenting the platform or setting up multiple systems to make recognition more manageable.

Investigate Incidents and Stay Compliant

Define your intrusion response plan to include specialists who can respond effectively without disrupting your business for too long. If your company needs to adhere to certain requirements, such as SOC 2, GDPR, or HIPAA, determine appropriate controls and follow the established protocols. Also, you may want to add another platform specifically designed for threat investigation after your IDS picks them up.

Keep Your Network Unscathed

An intrusion detection system goes a long way in protecting your network from data theft. It raises alarms, so you can investigate various issues and stop hackers in their tracks.

Just don’t forget to combine your IDS with other security measures to maximize the system’s efficiency. It’ll help create a nearly impenetrable network.



Frequently Asked Questions

What’s the main purpose of an IDS?

An IDS can be programmed to do many things. However, its main job is to monitor your network 24/7 and inform you of intrusion attempts.

What’s the difference between an IDS and Firewall?

A firewall limits network access to prevent unauthorized access, but it doesn’t monitor attacks from within the network. Conversely, an IDS describes intrusions and sends alarms.

Does an IDS record incidents?

Yes. Your IDS logs security incidents in its logs, whether it’s a major or minor alert. You can use this knowledge for future audits and references.

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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