What’s the difference between an IDS and a firewall?

An IDS monitors and alerts about suspicious activities, while a<a href="https://www.huntress.com/cybersecurity-101/topics/guide-to-firewalls" > firewall blocks unauthorized traffic</a>. They often work together to protect systems.

What is an Intrusion Detection System (IDS)?

Written by: Monica Burgess

Published: 9/26/2025

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An Intrusion Detection System (IDS) is a security tool that monitors network traffic for suspicious activities or unauthorized access attempts. When it detects something fishy, it sends alerts so your team can investigate and take action.

How does an IDS work?

Think of an IDS as a security camera for your network. It constantly watches the flow of data and looks for anything unusual, like signs of a break-in or someone tampering with systems.

There are two main ways an IDS spots trouble:

Signature-based monitoring looks for patterns matching known cyberattack methods, similar to how antivirus software works.
Anomaly-based monitoring focuses on spotting behaviors outside the norm, like a user suddenly downloading gigabytes of data at 3 AM.

Once any unusual activity is flagged, the IDS sends an alert to your IT or security team for assessment.

Types of Intrusion Detection Systems

Network-based IDS (NIDS): Monitors traffic across an entire network.
Host-based IDS (HIDS): Focuses on detecting threats on specific devices or endpoints.

Both forms are excellent at catching threats early, especially when used together to cover different parts of your environment.

Why is an IDS important in cybersecurity?

Keeping systems secure is tougher than ever with attackers devising smarter ways to exploit networks. An IDS helps businesses:

Spot threats early before they cause damage.
Safeguard sensitive data from being leaked or stolen.
Enhance situational awareness by keeping tabs on network behavior.

It’s an essential piece in the cybersecurity puzzle, along with firewalls, encryption, and other security measures.

How to use an IDS effectively

To make the most out of an IDS:

Regularly update signatures or baselines to stay ahead of new threats.
Combine it with other tools, such as firewalls and anti-malware systems, for a layered defense.
Set up actionable alerts that minimize false positives and enable swift responses.

With a properly configured IDS, businesses can strengthen their defenses and reduce the risk of data breaches.

Top 4 FAQs

An IDS monitors and alerts about suspicious activities, while a firewall blocks unauthorized traffic. They often work together to protect systems.

No, an IDS is a detection tool. It alerts you about potential threats so you can act, unlike a firewall or intrusion prevention system (IPS), which blocks attacks in real time.

Absolutely! While businesses of all sizes can benefit, small businesses are particularly vulnerable to cyberattacks. An IDS can provide an extra layer of security without needing large budgets.

Consider your specific needs, such as network size and the type of data you handle. It’s also a good idea to combine IDS with other security tools for a more robust strategy.

Additional Resources

Read more about What is an Intrusion Prevention System?
What is an Intrusion Prevention System?
Learn what an Intrusion Prevention System (IPS) is, how it blocks threats, and why it’s a crucial part of any cybersecurity plan. | Huntress
Read more about What is NGFW IPS?
What is NGFW IPS?
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Read more about What is a Blue Team?
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Read more about What is Big Game Hunting?
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Read more about What is Opentracing?
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Read more about What Is Suricata? A Powerful Cybersecurity Tool Explained
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Protect What Matters

Secure endpoints, email, and employees with the power of our 24/7 SOC. Try Huntress for free and deploy in minutes to start fighting threats.

Try Huntress for Free

What is an Intrusion Detection System (IDS)?

Written by: Monica Burgess

Published: 9/26/2025

Summarize This Page

On This Page

How does an IDS work?

Think of an IDS as a security camera for your network. It constantly watches the flow of data and looks for anything unusual, like signs of a break-in or someone tampering with systems.

There are two main ways an IDS spots trouble:

Signature-based monitoring looks for patterns matching known cyberattack methods, similar to how antivirus software works.
Anomaly-based monitoring focuses on spotting behaviors outside the norm, like a user suddenly downloading gigabytes of data at 3 AM.

Once any unusual activity is flagged, the IDS sends an alert to your IT or security team for assessment.

Types of Intrusion Detection Systems

Network-based IDS (NIDS): Monitors traffic across an entire network.
Host-based IDS (HIDS): Focuses on detecting threats on specific devices or endpoints.

Both forms are excellent at catching threats early, especially when used together to cover different parts of your environment.

Why is an IDS important in cybersecurity?

Keeping systems secure is tougher than ever with attackers devising smarter ways to exploit networks. An IDS helps businesses:

Spot threats early before they cause damage.
Safeguard sensitive data from being leaked or stolen.
Enhance situational awareness by keeping tabs on network behavior.

It’s an essential piece in the cybersecurity puzzle, along with firewalls, encryption, and other security measures.

How to use an IDS effectively

To make the most out of an IDS:

Regularly update signatures or baselines to stay ahead of new threats.
Combine it with other tools, such as firewalls and anti-malware systems, for a layered defense.
Set up actionable alerts that minimize false positives and enable swift responses.

With a properly configured IDS, businesses can strengthen their defenses and reduce the risk of data breaches.

Top 4 FAQs

An IDS monitors and alerts about suspicious activities, while a firewall blocks unauthorized traffic. They often work together to protect systems.

No, an IDS is a detection tool. It alerts you about potential threats so you can act, unlike a firewall or intrusion prevention system (IPS), which blocks attacks in real time.

Absolutely! While businesses of all sizes can benefit, small businesses are particularly vulnerable to cyberattacks. An IDS can provide an extra layer of security without needing large budgets.

Consider your specific needs, such as network size and the type of data you handle. It’s also a good idea to combine IDS with other security tools for a more robust strategy.

Additional Resources

Read more about What is an Intrusion Prevention System?
What is an Intrusion Prevention System?
Learn what an Intrusion Prevention System (IPS) is, how it blocks threats, and why it’s a crucial part of any cybersecurity plan. | Huntress
Read more about What is NGFW IPS?
What is NGFW IPS?
NGFW IPS integrates next-gen firewall and intrusion prevention to block cyber threats in real-time. Explore its advanced features and role in network security.
Read more about What Is Log Analysis Benefits and Uses in Cybersecurity
What Is Log Analysis Benefits and Uses in Cybersecurity
Learn what log analysis is, how it works in cybersecurity, and why it’s vital for threat detection, compliance, and performance. Simplify your strategy today.
Read more about Observability
Observability
Discover what observability is, how it differs from monitoring, and why it’s a game-changer for modern cybersecurity teams.
Read more about Default Deny Cybersecurity Approach Defined
Default Deny Cybersecurity Approach Defined
Learn about default deny cybersecurity, how it works, key benefits, and why it’s critical for securing networks from modern threats.
Read more about What is a Blue Team?
What is a Blue Team?
Learn what a blue team is in cybersecurity, how they defend networks, and their key role in protecting organizations. Stay informed with Huntress.
Read more about What is Big Game Hunting?
What is Big Game Hunting?
Big Game Hunting is a targeted ransomware attack on major organizations. Learn how hackers exploit high-value targets and tips to protect your business.
Read more about What is Opentracing?
What is Opentracing?
OpenTracing and OpenTelemetry's core purpose is driving better app performance and system transparency. See how they benefit businesses of any size with enhanced monitoring and scalability.
Read more about What Is Suricata? A Powerful Cybersecurity Tool Explained
What Is Suricata? A Powerful Cybersecurity Tool Explained
What is Suricata used for in cybersecurity? Learn how this open-source IDS/IPS tool protects networks with detection, prevention & monitoring features.

Protect What Matters

Secure endpoints, email, and employees with the power of our 24/7 SOC. Try Huntress for free and deploy in minutes to start fighting threats.

Try Huntress for Free

What is an Intrusion Detection System (IDS)?

How does an IDS work?

There are two main ways an IDS spots trouble:

Types of Intrusion Detection Systems

Why is an IDS important in cybersecurity?

How to use an IDS effectively

Top 4 FAQs

What’s the difference between an IDS and a firewall?

Can an IDS prevent attacks?

Is an IDS suitable for small businesses?

How do I choose the right IDS for my organization?

Additional Resources

Protect What Matters

What is an Intrusion Detection System (IDS)?

How does an IDS work?

There are two main ways an IDS spots trouble:

Types of Intrusion Detection Systems

Why is an IDS important in cybersecurity?

How to use an IDS effectively

Top 4 FAQs

What’s the difference between an IDS and a firewall?

Can an IDS prevent attacks?

Is an IDS suitable for small businesses?

How do I choose the right IDS for my organization?

Additional Resources

Protect What Matters