What Is Network Security Monitoring?
Modern networks are complex, distributed, and constantly targeted by attackers. For security teams protecting enterprise, federal, and critical infrastructure environments, visibility into network activity is essential.
Network Security Monitoring (NSM) provides that visibility by continuously observing network traffic—at the packet level with SentryWire—to help teams detect suspicious behavior, investigate incidents, and preserve defensible evidence when something goes wrong. Unlike general network monitoring, NSM is purpose-built for security operations, focusing on threat detection, incident response, and forensic validation rather than availability or performance metrics alone.
In this article, we explain what network security monitoring is, how it works, and why packet-level visibility plays a critical role in detection, response, and compliance. We’ll also cover how NSM differs from approaches like Network Detection and Response (NDR), which monitoring protocols matter most, and why full packet capture is the foundation of effective network security monitoring.
What Is Network Security Monitoring?
Network Security Monitoring (NSM) is the continuous collection, analysis, and alerting of network activity to identify security threats, policy violations, and suspicious behavior across network infrastructure. As a form of cybersecurity monitoring, NSM gives security teams continuous visibility into network activity so they can detect, investigate, and validate security threats.
Rather than relying on a single signal, NSM examines packet-level traffic, protocol behavior, and indicators of compromise to detect malicious activity as it occurs—and to preserve authoritative, high-fidelity evidence for investigation after the fact with corresponding logs for each session.
At its core, network security monitoring helps security teams answer three essential questions:
What is happening on the network right now?
What happened during a security incident?
Can we prove it with defensible evidence?
How Network Security Monitoring Identifies Threats
NSM supports threat detection by examining:
Network traffic flows and packet data
Communication patterns between systems and devices
Network behaviors such as lateral movement, command-and-control (C2) communication, and data exfiltration were identified through packet-level evidence
Known indicators identified by intrusion detection systems (IDS)
By continuously capturing and preserving network traffic, NSM enables detection tools and analysts to identify threats earlier and respond faster—before incidents escalate into full security breaches.
NSM vs. Other Monitoring Approaches
Network security monitoring is often confused with related—but distinct—approaches:
Perimeter security focuses on firewalls and access controls at network boundaries.
Log monitoring analyzes system and application logs after events occur.
Endpoint detection monitors activity on individual devices.
NSM complements these approaches by monitoring traffic between systems, where many modern attacks unfold. Unlike general-purpose network performance tools, NSM is designed for security-specific use cases rather than performance or availability monitoring.
Advanced NSM platforms support detection by supplying deep packet inspection (DPI) data to IDS engines such as Suricata, generating alerts based on packet content and protocol behavior. When NSM is built on full packet capture, it delivers total network visibility—capturing every packet rather than relying on summarized flow metadata. This packet-level visibility is essential for accurate forensics, threat validation, and regulatory compliance.
Benefits of Network Security Monitoring
Security and Operational Benefits
By enabling continuous security monitoring, NSM improves security operations by providing:
Early detection of unauthorized access and insider activity
Identification of lateral movement and anomalous east-west traffic
Detection of data exfiltration attempts and C2 communications
Faster triage and investigation of security incidents
Improved root-cause analysis using packet-level evidence
Because NSM continuously monitors network behavior, security teams gain visibility into both known and unknown threats, reducing dwell time and improving response accuracy.
Compliance, Governance, and Evidence
Beyond threat detection, network security monitoring plays a critical role in governance and compliance. Many regulations require organizations to produce audit-ready evidence demonstrating what occurred during a security incident.
Packet-level network visibility supports compliance with mandates such as:
PCI DSS
FISMA
SEC Rule 17a-4
SOC 2
HIPAA
NERC-CIP
Long-term packet retention allows organizations to validate incidents, support investigations, and defend decisions months or even years after the fact—capabilities that log-only or flow-only monitoring cannot reliably provide.
Features of Network Security Monitoring
Modern network security monitoring tools are designed to deliver continuous visibility into network activity while preserving high-fidelity data for investigation and compliance.
Core Capabilities of Modern NSM
A modern network security monitoring system must provide continuous visibility into network traffic while supporting both real-time detection and retrospective investigation. Core capabilities include:
Continuous monitoring of network traffic
Visibility across north-south and east-west flows
Full packet capture and session reconstruction
Integration with network intrusion detection systems (IDS)
Correlation across packets, flows, and IDS alerts
High-fidelity logs for all application protocols
These capabilities enable both real-time detection and detailed retrospective investigation.
Advanced Requirements for Enterprise and Federal Environments
Enterprise, federal, and ICS/OT environments place additional demands on network security monitoring systems, including:
High-speed ingestion for 10Gbps+ networks
Long-term packet retention without gaps
Secure, tamper-resistant evidence storage
Integration with SIEM and SOAR platforms
Visibility into encrypted traffic through metadata, session context, and protocol behavior
Scalability across complex network architectures
Enterprise-grade NSM platforms should enable retention of full packet data for weeks, months, or years—based on customer-defined storage strategies—using cost-effective commodity hardware that reduces total cost of ownership without sacrificing performance or forensic integrity.
NSM vs. NDR (Network Detection and Response)
Key Differences Between NSM and NDR
While often discussed together, NSM and NDR serve different purposes:
Network Security Monitoring (NSM) focuses on continuous visibility, evidence collection, and monitoring of network activity.
Network Detection and Response (NDR) focuses on automated detection, analytics, and response actions.
NSM provides authoritative, high-fidelity packet data. NDR platforms apply analytics and automation on top of that data, relying on NSM for validation and forensic accuracy.
How NSM and NDR Work Together
NSM and NDR are complementary, with NSM serving as the foundational evidence layer beneath detection and response platforms.
NSM supplies packet-level data needed to:
Validate NDR alerts
Investigate false positives
Reconstruct incidents accurately
Support compliance and reporting requirements
In this model, NSM acts as the source of truth. SentryWire enables this approach by delivering continuous packet capture and long-term retention that strengthens detection accuracy and investigative confidence. Explore SentryWire’s threat hunting capabilities.
Use Cases for Network Security Monitoring
Real-World NSM Applications
Common network security monitoring use cases include:
Threat hunting across historical network data
Insider threat detection
Command-and-control (C2) traffic identification
Data exfiltration analysis
Investigation of security incidents
Monitoring of critical infrastructure networks
In ICS/OT environments, packet-level monitoring supports safety and resilience by detecting anomalous traffic that could impact operational systems.
How SentryWire Supports Network Security Monitoring
SentryWire enables network security monitoring by providing:
Long-term packet capture retention
High-fidelity evidence for retrospective investigation
Scalable performance for 10Gbps+ environments
Visibility across enterprise, federal, and ICS/OT networks
This architecture empowers SOC teams, incident responders, and compliance auditors with continuous access to authoritative network evidence—without packet loss or storage constraints.
When a security incident occurs, this packet-level visibility becomes essential for incident response investigations. Learn how SentryWire supports incident response with forensic-grade network evidence.
Full Packet Capture and Network Security Monitoring
Network Security Monitoring is a core component of modern cybersecurity. By continuously observing network activity, NSM enables early threat detection, accurate investigation, and defensible compliance reporting.
As attacks become more sophisticated and regulatory expectations increase, packet-level evidence is no longer optional for effective security operations. Network security monitoring backed by full packet capture provides the visibility and confidence security teams need to protect high-stakes environments.
SentryWire delivers the enterprise-grade foundation for effective network security monitoring, combining full packet capture, long-term retention, and scalable performance across complex networks. See how SentryWire supports network security monitoring with full packet capture.