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What is a Network-Based Intrusion Detection System (NIDS)?
A network-based intrusion detection system (NIDS) is a type of intrusion detection system (IDS) that monitors traffic at strategic points within a private network and alerts administrators when there is suspicious activity.
Key Takeaways
- NIDS is a type of intrusion detection system that monitors network traffic.
- They are designed to complement other security controls in a private network.
- NIDS can be deployed as hardware or software.
- Some types of NIDS monitor all traffic passing through a network. Others monitor traffic on specific network segments.
- NIDS are passive, which means they can only observe network traffic and send an alert for further action when they detect suspicious activity.
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What Does a Network-Based IDS Do?
The primary functions of a NIDS are to monitor network traffic, detect potential threats, and generate alerts that contain details about the nature of the threat, its source, and its potential target.
NIDS are designed to complement firewalls, anti-virus software, and other security controls that support a defense in depth approach to cybersecurity.
How Does a Network-Based Intrusion Detection System Work?
A network-based intrusion detection system analyzes data packet headers and payloads as they flow across strategic points in a private network.
NIDS software can be deployed locally on physical or virtual appliances or purchased as a cloud managed service. A mixed approach that combines on-premises with cloud-based NIDS deployments can provide consistent security monitoring across hybrid cloud computing environments.
NIDS is passive. This means that when a NIDS detects suspicious activity, the only thing it can do is generate an alert to notify administrators. It is then up to the administrators or other security tools to take further action, such as blocking malicious traffic or isolating affected network segments and hosts.
NIDS can be purchased and deployed as dedicated hardware appliances or network sensors. NIDS software can also be installed locally or purchased as a cloud service. The flexibility in deployment options allows organizations to choose the best fit for their specific needs, infrastructure, and budget.
Who is NIDS For?
NIDS cyber security solutions are typically used by large IT departments. They are also useful for organizations that need to comply with strict regulations for monitoring and logging network activity.
Methods of NIDS Detection
Network-based intrusion detection systems use three basic methods to detect suspicious or malicious activity on a network: signature-based detection, anomaly-based detection, and hybrid detection.
While these three methods traditionally required significant manual configurations, advancements in machine learning (ML) and artificial intelligence (AI) have improved their efficiency, adaptability, and accuracy in identifying a wider range of cyber threats.
Difference Between Signature-Based NIDS, Anomaly-Based NIDS & Hybrid NIDS
Signature-based detection compares network traffic patterns against a database of known attack patterns called “signatures.”
Anomaly-based detection establishes a baseline of what is considered “normal” network behavior and flags any significant deviation as a potential threat.
Hybrid detection combines both signature-based and anomaly-based methods. This approach compensates for anomaly-based detection’s tendency to generate too many alerts and signature-based detection’s inability to recognize zero-day threats.
NIDS Types
NIDS can be categorized based on where they are deployed within a network architecture. The deployment location affects the type of traffic the NIDS monitors and the specific role it plays in network security.
| Type of NIDS | Deployment Location | Purpose |
|---|---|---|
| Perimeter NIDS | Deployed at the perimeter of a private network. | Monitor traffic entering and leaving the private network. |
| Internal NIDS | Deployed within specific internal network segments | Monitor lateral movement within the network. |
| Host-based NIDS (HIDS) | Deployed directly on individual hosts or servers. | Monitor traffic to and from specific network devices at a granular level. |
| Cloud-based NIDS | Deployed in cloud environments and purchased as a service. | Monitor traffic within and to/from cloud-based resources. |
| Distributed NIDS | Involves deploying multiple NIDS sensors across various network segments of a large, distributed network. | Provides a holistic view of the network’s security across multiple network segments. |
| Network core NIDS | Strategically deployed near routers, switches, or other critical network infrastructure. | Monitor for advanced persistent threats that target critical network infrastructure. |
NIDS vs. HIDS
Intrusion detection systems can also be categorized by whether they are network-based (NIDS) or host-based (HIDS). Both types of IDS are deployed to monitor network traffic alert admins to? suspicious activity, but they go about achieving this goal differently.
Essentially, network intrusion detection systems monitor packets, and host-based intrusion detection systems monitor activity on a specific host.
| Network-Based IDS | Host-Based IDS | |
| Primary focus | Monitor network traffic for suspicious activity. | Monitors specific host activities for signs of compromise. |
| Deployment location | Deployed at strategic points within a network. | Installed directly on individual hosts or servers. |
| Analysis | Network packets, including headers and payloads. | System logs, file integrity, process activity, and local network traffic. |
| Resource usage | Low. | Can be resource-intensive. |
What Technologies Does Network-Based Intrusion Detection System Monitor?
A network-based intrusion detection system monitors network traffic, but that traffic can originate from (and be destined for) a wide range of technologies, including:
Network-Based Intrusion Detection System Pros and Cons
NIDS can help identify attacks in their early stages and allow network security teams to respond quickly. Like any technology, however, network-based intrusion detection systems have advantages and disadvantages.
- Provides IT administrators with a way to monitor network traffic
- NIDS can be configured to monitor the entire network or specific segments
- Can be very effective against known attack vectors and significant deviations in network traffic patterns
- Cannot analyze the contents of encrypted data packets
- Can only issue alerts
- Requires human intervention or integration with other security tools that can take action
- Can generate false positives and make IT staff waste time investigating non-threatening events
The Bottom Line
Network-based intrusion detection system definitions are often confused with intrusion prevention system (IPS) definitions because both systems analyze network traffic to identify potential threats.
To add to the confusion, the line between NIDS and IPS is becoming increasingly blurred as vendors use artificial intelligence and machine learning to create managed detection and response (MDR) products and services that merge the capabilities of detection and prevention into more comprehensive security solutions.
FAQs
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References
- About Zeek — Book of Zeek (git/master) (Docs.zeek)
