What Is Network Access Control (NAC)? | Acrisure Cyber Services

Network Access Control (NAC) is a security solution that controls who and what can join your network based on access policies, authentication, and compliance checks.

As modern networks expand due to BYOD (Bring Your Own Device), remote work policies, and IoT devices, managing network access is more complicated – but as critical as ever.

To help you safeguard your networks effectively, we explain the main parts of NAC, different ways to deploy it, what benefits you can expect, and challenges you might face.

Overview: What Is Network Access Control?

Network Access Control acts as your network’s gatekeeper. It ensures that only authenticated devices and users are allowed on your network based on predefined security policies.

NAC works on the principle of least privilege. This means users only get access to the systems and data they actually need for their work. The objective is to protect data and other sensitive resources by preventing unauthorized access and restricting unwarranted movement within the network.

How Does Network Access Control Work?

Network Access Control works by managing access and monitoring behavior strictly on the network. It has two operational phases backed by enforcement actions:

Pre-admission control

When a device or user requests to connect to your network, NAC conducts checks. These include validating credentials (like a username and password) or a digital certificate.

NAC also verifies that the device meets your security standards. Is it running the latest security patches? Does it have active antivirus software? If the device fails these checks, it gets blocked from the network.

Post-admission control

NAC monitors the usage of all connected devices, watching for suspicious behavior or policy violations, like malware or unauthorized probing. If behavior deviates from policy or appears risky, NAC takes immediate action.

Enforcement includes

Denying access entirely
Placing suspicious devices in an isolated network (VLAN assignment)
Quarantining non-compliant endpoints

Types of Network Access Control

NAC comes in four main forms, each suited to different needs:

Agent-based NAC: This involves installing a small piece of software on devices like laptops or phones. The software (or agents) sends detailed security information to the NAC system, giving you a clear view of each device’s security status.

Agentless NAC: This approach uses network-level protocols and device profiling instead of installed software. It’s useful for controlling guest or contractor laptops and IoT devices where installing an agent isn’t practical.

Inline NAC: Inline NAC sits directly in the traffic path between the device and the network. It enforces policies in real time and can be highly effective, but potentially represents a single point of failure.

Out-of-band NAC: This method monitors the network and enforces policies from an external controller. It’s less disruptive to network performance and is well-suited for larger, more complex environments.

Key Components of NAC

A comprehensive NAC network solution comprises several components that work together:

Authentication

Profiles users/devices and verifies their identity via usernames, passwords, multi-factor authentication (MFA), and digital certificates.

Authorization

Defines the level of access for each user and device. This is set based on roles and access policies.

Compliance checks

Ensure that every endpoint meets required security standards. Does it have the latest operating system patches and active antivirus software? Is it compromised by known vulnerabilities?

Policy engine

This is the brain of the NAC system. It makes informed decisions about who and what gets access and what they can do once connected.

Remediation/quarantine

Non-compliant and infected devices are isolated from the network, and the user is guided on remedial steps.

Monitoring and reporting

Provides a bigger picture of all devices on the network, helping security teams track and detect anomalies.

Benefits of Network Access Control

NAC offers several practical advantages for businesses:

Consistent policy: Ensures that security policies are enforced consistently across all access points, simplifying network management and reducing the risk of human error.
Greater network visibility: NAC provides a high-level view of every device, user, and IoT endpoint connecting to your network. This information helps you spot and fix issues quickly.
Reduced insider threats: Proper controls make it harder for users within the network to gain unauthorized access to sensitive data.
Regulatory compliance: NACsupports compliance with regulations like HIPAA, GDPR, and PCI DSS.
Preventing malware spread: Quarantining infected devices prevents malware from contaminating your network.

Challenges of Network Access Control

While NAC provides important security benefits, there are some challenges to consider:

Complexity

Implementing and managing a NAC solution can be complex and time-consuming. This is especially true in large, diverse network setups.

Integration

Depending on your legacy system/security tools, integrating NAC might create unexpected technical problems that take time and resources to solve.

Productivity disruption

Poorly designed NAC can make it harder for employees to access the tools and information needed to do their jobs, dragging down productivity.

Cost

The upfront investment and ongoing management overhead are often costly. Typically, the larger and more complex the system, the heftier the bill.

NAC vs. Firewalls and VPNs

Firewalls and VPNs are security tools often used in combination with NAC to strengthen access controls.

A firewall controls traffic flowing in and out of the network based on security policy compliance. It acts as a barrier, blocking data from potentially malicious or unauthorized connections.

A VPN (Virtual Private Network) facilitates a secure, encrypted connection for remote users. Devices/users connecting via VPN must still comply with NAC policies.

This table summarizes how each contributes to secure access controls.

Security Solution

Function

What it controls

Example

Network Access Control (NAC)

Authentication and authorization

Who and what gets network access at the device and user level

A laptop is granted access to the network only after its antivirus software is validated.

Firewall

Traffic control

What traffic can flow in or out of the network

The firewall blocks a malicious IP address from sending data to the internal network.

VPN

Secure connection

How a remote user connects to the network securely

A remote employee connects to the corporate network via an encrypted tunnel.

How Acrisure Cyber Can Help?

Acrisure Cyber’s Network Management and Network Security services provide bespoke NAC solutions designed to fight network threats. In a time when cyberattack victim notices have increased by 211% from 2023 to 2024, effective network protection has never been more important.

We work with you to develop the right NAC solution for your business needs. Our expertise includes:

Security posture checks to identify access vulnerabilities
NAC framework design and implementation
Integration with your existing infrastructure
Ongoing monitoring and compliance
Optimized NAC in BYOD and IoT environments

Contact us

to learn more about protecting your network.

FAQs

What is NAC in cybersecurity?

NAC in cybersecurity regulates which devices and users can connect to a network. It confirms identity, device health, and compliance to ensure that only secure and authorized endpoints are granted access.

How does Network Access Control improve security?

NAC improves security by restricting access to the network based on predefined policies, preventing unauthorized devices and users from connecting. It reduces the attack surface while providing visibility into all connected devices.

What are the two main types of NAC?

The two main types of NAC are:

Pre-admission NAC: Checks that a device is compliant and verifies the user’s credentials before allowing the device on the network. Compliance checks include inspecting for proper antivirus, patches, and configurations.
Post-admission NAC: Monitors devices already connected to ensure that users’ behaviors don’t violate policies. Breaches and unauthorized usage are detected and addressed.

Is NAC the same as a firewall?

No. A firewall controls traffic between networks by allowing or blocking data flow based on predefined rules. NAC controls who or what can connect to the network.

What’s the difference between agent-based and agentless NAC?

Agent-based NAC involves installing software on each endpoint. This provides a detailed picture of every device’s configurations and security status.

Can NAC block infected devices from joining the network?

Yes, NAC can detect non-compliant or infected devices during the authentication process. They can deny them access, place them in quarantine, or restrict them to an isolated network.

What are examples of NAC solutions?

Examples of Network Access Control (NAC) solutions include:

Cisco Identity Services Engine (ISE)
Aruba ClearPass
Fortinet FortiNAC

These leading platforms provide advanced access regulation, visibility, and policy enforcement for complex networks.

How does NAC support compliance regulations?

A core focus of regulations like HIPAA, PCI DSS, and GDPR is protecting the privacy and integrity of customer data. NAC supports this mission via measures that ensure only compliant devices and authenticated users access sensitive data or systems.

Does NAC work in cloud and hybrid environments?

Yes, NAC solutions work in both cloud and hybrid environments. They integrate with cloud platforms and support hybrid structures, enforcing policies and protection across remote devices and distributed teams.