What is network access control (NAC)? Benefits and how it works

Not long ago, most corporate networks were straightforward. Employees worked from the office, used company-issued computers, and all systems operated safely behind a firewall. Those days are long gone.

Today, staff connect from coffee shops, family members may use work laptops for personal tasks, and conference rooms are filled with smart TVs that require network access. Add remote work, personal devices, and IoT gadgets to the mix, and the network perimeter quickly develops multiple points of vulnerability.

Traditional security approaches were not designed for this reality. They operate on the assumption that once a user is inside the network, they should have unrestricted access. When “inside” can include a contractor’s personal laptop connected through public Wi-Fi, that assumption becomes dangerous.

Network access control (NAC) changes this dynamic by shifting the model from “access first, verify later” to continuous verification at every entry point. It inspects each device, user, and connection request in real time, allowing only those that meet security policies to proceed.

In an era of hybrid work, bring-your-own-device (BYOD) policies, and a flood of connected IoT systems, NAC has moved from a background measure to a frontline defense. It gives IT teams the visibility to see exactly what is on the network and the control to manage access without slowing operations.

In this piece, we show how NAC works, the main solution types, and the steps to create an approach that secures your network without slowing it down.

What is network access control (NAC)?

Network access control, also known as network admission control, is a security solution that enforces policies determining who or what can connect to a network, ensuring only authorized users and devices gain access. 

Unlike traditional firewall or antivirus solutions that focus on blocking bad traffic after it's already on your network, NAC controls access before full network entry. It creates a checkpoint where every device and user must prove they belong before getting connected to network resources.

The key difference between NAC and other security tools is its focus on identity and compliance verification. While firewalls block traffic based on network rules and antivirus software scans for malware, NAC asks fundamental questions: 

• Who is this user?

• Is their device compliant with our network security policies?

• What level of access should they have?

• Are they behaving normally?

This approach becomes especially important in modern hybrid work environments where the traditional network perimeter has largely disappeared. NAC helps organizations maintain security control regardless of where users connect from or what devices they use.

Types of network access control

NAC solutions generally fall into two main categories based on when they enforce security policies and how they monitor device behavior:

Pre-admission NAC

Pre-admission NAC checks devices before they are allowed onto the network. 

It scans for compliance with security policies, such as required software, updates, and configurations. This helps ensure that only trusted and compliant devices can connect.

Post-admission NAC

Post-admission NAC evaluates devices after they have connected to the network. 

This approach monitors activity and re-checks compliance when a device tries to access different parts of the network. If suspicious behavior is detected, access can be restricted or the device can be quarantined.

Why is network access control important for businesses?

The traditional approach to network security (assuming that anything inside the network can be trusted) no longer works in today's complex IT environments. 

NAC addresses several critical security risks that have emerged as business networks have evolved:

• Preventing unauthorized device access by blocking unmanaged or insecure devices from connecting.

• Detecting internal threats by spotting unusual access patterns or suspicious device behavior.

• Supporting regulatory compliance with detailed access controls, logs, and audit trails for standards like HIPAA, PCI-DSS, and GDPR.

• Simplifying hybrid work security by automating access management across locations, devices, and environments.

In summary, NAC gives businesses the visibility and control needed to protect networks, meet compliance requirements, and support secure hybrid work.

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Benefits of network access control

Implementing NAC delivers several concrete security and operational benefits that directly address the challenges of modern network management:

Prevents data breaches from unmanaged or rogue devices

NAC stops unauthorized devices from accessing network resources before they can cause damage. By scanning devices for compliance and blocking non-compliant connections, organizations significantly reduce the risk of malware infections and data theft through compromised endpoints.

Helps meet compliance standards

Many regulatory frameworks require organizations to control and monitor network access. NAC provides the detailed access logs, user authentication records, and device compliance documentation that auditors expect. This is particularly important for industries like healthcare, finance, and government that face strict compliance requirements.

Improves endpoint visibility

NAC gives IT teams complete visibility into what devices are connecting to the network, who's using them, and what they're accessing. This visibility extends to personal devices in BYOD environments and IoT devices that might otherwise operate invisibly on the network.

Enables secure BYOD policies

With proper NAC implementation, organizations can safely allow personal devices on corporate networks. The system can enforce different access policies for personal versus corporate devices, ensuring that BYOD doesn't compromise security while maintaining employee productivity and satisfaction.

How network access control works

NAC solutions function through a systematic process that evaluates every connection attempt and enforces appropriate access policies based on predefined rules and real-time assessments.

When a device attempts to connect to the network, the NAC system immediately begins an evaluation process. First, it checks the user's credentials through integration with authentication services. This ensures that only authorized users can even attempt to connect their devices.

Next, the system performs endpoint compliance scans to verify that the connecting device meets established security policies. This might include checking for updated antivirus software, required security patches, proper encryption settings, or approved applications. The NAC solution compares the device's current state against organizational security requirements.

Based on the authentication results and compliance assessment, the NAC system makes an access decision. Compliant devices from authorized users might receive full network access, while non-compliant devices could be placed in a quarantine network. Completely unauthorized devices are blocked entirely.

Throughout the connection session, many NAC solutions continue monitoring device behavior and can adjust access privileges in real time. If a device begins exhibiting suspicious behavior or falls out of compliance, the system can immediately restrict access or disconnect the device entirely.

Key components of network access control

Effective NAC solutions integrate several technical components that work together to provide comprehensive network access control and monitoring.

Authentication systems

These components verify user identities and handle authorization decisions before granting any network access. Authentication systems typically integrate with existing directory services like Active Directory, LDAP, or cloud identity providers. They may support various authentication methods, including passwords, certificates, multi-factor authentication, or single sign-on integration.

Policy enforcement engines

The policy engine contains the rules and logic that determine what level of access each user and device should receive. These engines support role based access controls, evaluating multiple factors including user role and device compliance status.

Endpoint compliance scanners

These tools assess device security posture by checking for required software, security configurations, patch levels, and other compliance requirements. Scanners can operate through agent-based software installed on devices or through agentless network-based scanning techniques.

Guest management portals

Many NAC solutions include self-service portals that allow visitors and temporary users to register their devices and gain appropriate network access. These portals streamline the guest access process while maintaining security oversight and audit trails.

Automated remediation tools

When devices fail compliance checks, automated remediation tools can guide users through fixing common issues like updating antivirus software, installing security patches, or adjusting security settings. This reduces the burden on IT support while helping users quickly regain network access.

The 7 steps of the network access control process

NAC systems follow a structured process from initial device connection through ongoing monitoring and enforcement.

Step 1: Device request initiation

When a device attempts to connect to the network, the NAC system intercepts the connection request before allowing network access. The device is initially placed in a restricted network segment with minimal connectivity.

Step 2: Identity authentication

The NAC system prompts for user credentials and validates them against configured authentication sources. This step ensures that only authorized users can attempt to connect devices to the network, regardless of device compliance status.

Step 3: Device posture assessment

The system scans the connecting device to assess its security posture and compliance with organizational policies. This assessment checks for required security software, patch levels, configurations, and other compliance requirements specific to the organization's security policies.

Step 4: Policy evaluation

Using the authentication results and device assessment data, the NAC system evaluates applicable access policies. The system considers factors like user role, device type, compliance status, connection location, and time of access to determine appropriate access levels.

Step 5: Access decision

Based on policy evaluation, the system determines whether users and devices are granted access to full network resources, limited access, or denied entirely. This decision determines which network resources and applications the device can reach.

Step 6: Enforcement and monitoring

The NAC system implements the access decision by configuring network infrastructure to allow or restrict traffic from the device. Throughout the connection session, the NAC system logs activity and monitors device behavior for compliance and security issues. 

Step 7: Post-connection actions

If monitoring detects compliance issues or suspicious behavior, the NAC system can automatically adjust access levels, or disconnect it entirely. All actions are logged for security analysis and compliance reporting.

What are the top 5 network access control solutions?

NAC solutions vary significantly in their approaches, capabilities, and target markets. Here are five leading solutions that address different organizational needs and deployment scenarios.

1. Rippling

Rippling takes a uniquely integrated approach to network access control by combining NAC capabilities with comprehensive identity and access management in a unified platform. Rather than treating network access as a separate security function, Rippling connects device management directly with user lifecycle management through its unified HRIS and IdP system. This integration ensures that network access policies automatically align with user roles and employment status changes, providing stronger security with granular access controls across the entire user lifecycle.

2. Cisco Identity Services Engine

Cisco ISE provides enterprise-grade NAC capabilities with integration into Cisco networking infrastructure. The solution serves as a policy decision point in zero-trust architecture, gathering intelligence from across the network stack to authenticate users and endpoints while containing threats. ISE offers device profiling using multiple identification methods, supports various authentication protocols, including 802.1X, and integrates with threat intelligence systems for security posture assessment.

3. FortiNAC 

FortiNAC delivers NAC capabilities as part of Fortinet's broader security fabric approach, providing years of network access control experience. The solution offers device visibility with support for unique IoT device identities and management of networking equipment models. FortiNAC features agentless scanning, different device profiling methods, microsegmentation capabilities, and automated response workflows for threat mitigation.

4. NordLayer

NordLayer provides a multi-layered NAC approach designed for rapid deployment, with enterprise-grade protection. The solution offers control based on user identity, device posture, IP addresses, and location parameters. NordLayer integrates with major identity management platforms, including Google Workspace and Azure AD, while providing features such as network segmentation, biometric authentication, and jailbroken device detection.

5. Ivanti Policy Secure

Ivanti Policy Secure delivers unified, automated network access control with dynamic endpoint policy enforcement across any environment. The solution provides network visibility with automatic device detection and classification, endpoint compliance assessment for both 802.1X and non-802.1X environments, and behavioral analytics capabilities, including UEBA to detect IoT rogue devices and sophisticated attacks. The platform supports seamless roaming between VPN and on-premises networks while maintaining consistent policy enforcement.

Network access control use cases

NAC solutions address specific business scenarios where traditional security approaches fall short of providing adequate protection and control.

Enabling secure remote work

Remote employees connecting from home networks or public Wi-Fi need secure access to corporate resources without compromising security. NAC ensures that remote devices meet security requirements before accessing sensitive company data, regardless of the connection location.

Enforcing BYOD policies

BYOD programs improve employee satisfaction and reduce IT costs, but personal devices introduce security risks. NAC enables organizations to safely allow personal devices by enforcing different access policies based on device ownership and compliance status.

Managing IoT devices in healthcare or manufacturing

Healthcare facilities and manufacturing plants increasingly rely on IoT devices that need network connectivity but may lack traditional security controls. NAC provides visibility into these devices and can isolate them on separate network segments to prevent security risks.

Segmenting access for third-party vendors

Contractors and vendors often need temporary network access to perform their work, but shouldn't have the same access levels as employees. NAC can automatically provision appropriate access for vendor devices while maintaining strict controls and audit trails.

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Network access control challenges

While NAC provides significant security benefits, organizations often encounter obstacles during implementation that require careful planning and management.

Complexity of deployment in legacy networks

Older network infrastructure may lack the integration capabilities needed for modern NAC solutions. Organizations might need to upgrade switches, wireless controllers, or authentication systems to support NAC functionality. Phased deployment approaches can help manage this complexity by starting with critical network segments.

Device compatibility and visibility

Some devices, particularly IoT devices or older systems, may not support standard authentication protocols or agent-based compliance scanning. NAC solutions need device profiling capabilities to identify and appropriately handle these devices through alternative methods like MAC address authentication or network behavior analysis.

Policy misconfiguration or over-restriction

Poorly configured NAC policies can block legitimate users or provide excessive access to unauthorized devices. Organizations should start with permissive policies during initial deployment and gradually tighten restrictions based on observed usage patterns and security requirements.

Performance slowdowns during posture checks

Comprehensive device scanning can slow connection times, particularly for devices with limited processing power. Balancing security requirements with user experience requires optimizing scan configurations and potentially using risk-based assessment approaches for different device types.

High upfront cost for enterprise-scale NAC tools

Enterprise NAC solutions can require significant investment in software licensing, hardware infrastructure, and implementation services. Organizations should carefully evaluate their specific requirements and consider staged deployment approaches to manage costs while achieving security objectives.

Put access and identity management on autopilot with Rippling

While NAC typically operates at the network layer, identity and access management tools like Rippling are important for managing secure access to applications, systems, and devices across your entire organization. The two approaches complement each other perfectly—NAC controls what gets onto your network, while IAM controls what users can do once they're there.

Rippling transforms how organizations handle the user and device lifecycle by automating the complex processes that traditionally require manual coordination between HR and IT teams. When someone joins your company, changes roles, or leaves the organization, Rippling automatically adjusts their access permissions across all connected systems and applications.

Rippling's approach to device management integrates seamlessly with access control policies. Instead of managing network access separately from application access, Rippling provides unified control over both user accounts and device permissions. This integration ensures that access policies remain consistent whether someone is connecting to your network or accessing cloud applications.

The platform's single sign-on and multi-factor authentication capabilities extend security controls beyond the network perimeter to protect cloud applications and remote access scenarios. This comprehensive approach ensures that security policies remain effective regardless of how users connect to company resources.

Perhaps most importantly, Rippling provides complete visibility into user access patterns and permissions across your entire technology stack. When security incidents occur or audits require access reviews, you have comprehensive logs and current permission states available in one centralized location.

Network access control FAQs

What are network access control solutions?

Network access control solutions are security tools that enforce policies about who and what can connect to an organization's network. They authenticate users, assess device compliance with security policies, and grant appropriate access levels based on predefined rules. 

What is the difference between a firewall and NAC?

Firewalls control traffic flow between network segments based on network rules like IP addresses and port numbers, while NAC controls who can access the network in the first place based on user identity and device compliance. Firewalls operate at the network layer and focus on blocking malicious traffic, while NAC operates at the access layer and focuses on verifying that users and devices should be allowed on the network at all.

Does NAC work with cloud networks?

Yes, modern NAC solutions support cloud and hybrid environments through various approaches. Cloud-based NAC services can protect cloud infrastructure and applications, while on-premises NAC solutions often integrate with cloud identity providers and can enforce policies for users accessing cloud resources. Some NAC solutions also provide protection for cloud workloads and can extend access control policies across on-premises and cloud environments.