Why Network Access Control is Important and How to Implement It

default image

Network access control (NAC) has rapidly evolved into an essential cybersecurity capability for modern enterprises. As digital transformation accelerates across industries, companies are contending with exponential growth in users, devices, and applications accessing their networks. This massive expansion of the corporate attack surface requires a new approach to securing network access.

NAC provides the ability to allow network access only to trusted users and endpoints that comply with the organization‘s security policies. According to leading industry analyst firm Gartner, "NAC is becoming a cornerstone of the digital workplace that expands on identity and access management to provide comprehensive access control."

In this comprehensive guide, we will take a deep dive into NAC to understand:

  • What is Network Access Control and how does it work?
  • Why NAC is a must-have capability today
  • Different types of NAC architectures and solutions
  • Considerations for selecting a NAC product
  • Best practices for implementing NAC

Let‘s get started!

What Exactly is Network Access Control?

Network Access Control refers to various methods and tools used for regulating connectivity to network resources based on the device and user identity, security posture, and adherence to defined security policies.

NAC solutions achieve this by sitting at network ingress points and establishing policy enforcement checkpoints to prevent uncontrolled access. Let‘s examine the key mechanisms NAC employs:

User and Device Identification

When a device attempts to connect to the network, NAC first identifies it using attributes like MAC address, IP address, hostname, LDAP/AD credentials etc. Device profiling based on its operating system, manufacturer, type etc. may also be undertaken.

Authentication and Authorization

Next, the user or device is authenticated using methods like LDAP, RADIUS, PKI certificates etc. to verify their identity. The subject is then authorized and assigned network privileges based on their role.

Security Posture Assessment

A posture assessment evaluates the device‘s security health state before allowing access. Checks performed include verifying anti-virus status, OS patches, firewall settings, disk encryption status and other aspects.

Remediation and Quarantine

Non-compliant or compromised endpoints detected by NAC can be automatically quarantined and isolated from the network. Custom remediation actions may also be initiated by NAC to resolve security gaps.

Network Policy Enforcement

Finally, the verified identity, security state, and context of the subject are correlated with pre-defined network security policies to make an access decision and enforce appropriate network controls.

Why Network Access Control is Critical Now

Traditional perimeter security models are proving inadequate in the cloud-centric digital business era. According to Cisco‘s 2022 Data Privacy Benchmark Study, 52% of organizations surveyed suffered a data breach involving an unsecured device last year. NAC can strategically strengthen network security in the following ways:

Prevents Unauthorized Access

NAC enhances the first line of defense by preventing unmanaged, unknown, or unauthorized devices from entering the network – significantly reducing the attack surface for malicious actors.

Strengthens Insider Threat Protection

For employees and authorized third parties, NAC limits network access to only corporate-managed applications and resources based on role – containing insider threats.

Verifies Security Hygiene

NAC ensures that every device meets the mandated security standards like encryption, antivirus etc. before granting any access – closing security gaps that can be exploited.

Simplifies Network Segmentation

NAC allows creation of dynamic network segments that group users and devices based on risk profiles. Granular access policies are applied per segment preventing lateral movement.

Automates Threat Response

NAC expedites incident response by automatically detecting compromised hosts, triggering alerts and isolating them from the network within seconds.

Compliance Benefits

By consistently enforcing device security policies, NAC aids in meeting compliance mandates around endpoint security controls and access management.

According to research from Enterprise Management Associates, 95% of organizations surveyed see value in NAC for reducing security risks. Let‘s now examine the different NAC approaches.

Types of Network Access Control

NAC solutions typically fall into one of these architectural categories:

Inline NAC

Inline NAC solutions feature physical or virtual appliances installed at network chokepoints where all traffic must flow through. They enable policy enforcement by directly controlling access to network resources.

Inline NAC advantages include:

  • Ability to physically isolate segments using network infrastructure
  • Flexibility in enforcement locations – perimeter, internal network, wireless etc.
  • Enhanced visibility into lateral traffic flows

But inline NAC can introduce latency, performance constraints, and availability risks. Implementation requires changes to network topology.

Agent-based NAC

Agent-based NAC relies on lightweight software agents installed on endpoints to assess, communicate and enforce security policies via a centralized server. Key benefits include:

  • Rapid deployment without network changes
  • Scales seamlessly to large numbers of endpoints
  • Enables pre-connectivity enforcement checks

On the flip side, agent-based NAC has a performance overhead on endpoints and lacks network-level visibility.

Hybrid NAC

As the name indicates, hybrid NAC combines aspects of inline and agent-based NAC for policy enforcement. Software agents provide pre-admission control while network infrastructure aids in segment isolation, remediation and visibility.

The hybrid approach offers strengths of both models. But it also requires deploying multiple components, adding complexity.

How to Select The Right NAC Solution

Choosing the optimal NAC product entails evaluating your organization‘s specific requirements, infrastructure, and use cases across these key dimensions:

Deployment Models

Assess whether an on-premise, cloud-based, or hybrid NAC deployment allows implementing the required policies while minimizing disruption.

Endpoint Platform Support

Confirm NAC solution can handle all endpoint platforms like Windows, OSX, Chrome OS, iOS, Android, Linux, IoT devices etc. present within your environment.

BYOD and Guest Access

Evaluate NAC‘s automated BYOD onboarding and policy enforcement capabilities for employee devices. Also check flexible guest device management workflows.

Posture Assessment and Remediation

Review built-in posture checks and ability to customize compliance criteria based on your standards. Verify automated remediation and quarantine capacities.

Network Policy Enforcement

Assess NAC support for enforcing granular network access policies based on device type, role, location, application etc. to enable Zero Trust segmentation.

Scalability and Performance

Validate from vendor documentation and discussions that the NAC solution can scale seamlessly as users, devices and network traffic volumes grow without availability issues.

Centralized Visibility and Analytics

Evaluate depth of visibility into network activity and security events provided through dashboards, searching and reporting.

Orchestration and Automation

Review capabilities for automation, integrating with IT ticketing systems and workflows, and programmatically managing policies through APIs.

Total Cost of Ownership

Estimate direct and indirect costs across initial purchase, deployment, ongoing management and maintenance over the solution lifecycle.

Weighing the pros and cons relative to your organization‘s environment will help narrow down the ideal NAC product choice.

Implementing a NAC Solution

Implementing NAC involves several key phases:

Planning Phase

  • Define NAC requirements, priorities and success criteria
  • Create inventory of endpoints, users, network segments that NAC must handle
  • Outline policies for device compliance, guest access, BYOD, network segmentation etc.
  • Build roadmap, project plan, identify team roles and responsibilities

Design Phase

  • Select optimal NAC architecture – inline, agent-based or hybrid
  • Choose NAC product that aligns with requirements
  • Determine placement of enforcement points or agents
  • Plan integration touchpoints with other security and network systems
  • Document policies, test plans, and deployment methodology

Deployment Phase

  • Configure NAC software components and appliances based on design
  • Integrate with directory services like Active Directory for identity and context
  • Implement NAC agents on endpoints as applicable
  • Ensure NAC platform can interface with firewalls, web proxies, and other security tools
  • Activate automated remediation and quarantine workflows

Testing and Validation Phase

  • Perform functionality testing to verify all policies, rules, checks are working correctly
  • Conduct security validation by simulating attack scenarios to confirm enforcement
  • Fix issues identified and retest until all test cases pass
  • Start with small pilot groups to check for unforeseen impacts before wide-scale rollout

Ongoing Management Phase

  • Provide user training on any new procedures required by NAC implementation
  • Perform capacity planning as users, devices, applications scale up
  • Monitor infrastructure and endpoints flows to identify anomalies
  • Apply patches and upgrades to NAC components when released
  • Tune policies and rules based on learnings

A phased approach is recommended when applying NAC controls across large global networks and endpoint populations.

NAC Implementation Best Practices

Some key best practices to ensure a successful NAC deployment include:

Align to Business Goals

Tie the NAC implementation roadmap to defined cybersecurity objectives around access management, data protection, threat prevention etc.

Establish NAC Governance

Institute NAC policies, exception management processes, and enforcement rules based on framework like ISO or NIST. Maintain a change review board.

Get Organizational Buy-in

Educate stakeholders about NAC value proposition and get executive sponsor to ensure collaboration across IT, Security and Business groups.

Start with Visibility

Onboard NAC in monitoring mode first to discover all endpoints and gain visibility without enforcing restrictions initially.

Implement Controls in Phases

Start with basic device authentication and onboarding policies first. Expand to posture checks and microsegmentation policies later to minimize disruption.

Integrate with Other Security Systems

Integrate the NAC system into your broader security ecosystem including SIEM, firewalls, end point security etc. to share context.

Automate Processes

Automate policy configuration, endpoint onboarding, remediation and other workflows through the NAC platform to maximize efficiency.

Provide User Training

Conduct training for end-users to educate them about the NAC implementation, any new procedures to follow, and importance of compliance.

Start with Critical Assets

Prioritize securing network access for servers, endpoints and users handling sensitive applications or data via NAC first.

Monitor, Report and Optimize

Perform ongoing monitoring, generate reports to gain visibility into what‘s working as expected and identify areas for policy tuning.

Key Capabilities of NAC Solutions

Some of the major capabilities supported by leading NAC platforms include:

Centralized Policy Management

Creates a policy repository capturing compliance standards, authentication methods, access requirements, remediation actions etc. in a centralized manner.

Detailed Endpoint Visibility

Provides real-time visibility into endpoint inventory, software configurations, compliance status and network traffic patterns.

Posture Assessments

Performs pre-access evaluation of antivirus status, patch levels, firewall enablement etc. for compliance-based access control.

Guest and BYOD Management

Onboards employee and guest devices and applies appropriate policies without compromising security.

Device Profiling and Behavioral Analytics

Creates an identity profile for managed and unmanaged devices based on fingerprints, traffic patterns and machine learning for managing access risk.

Automated Remediation and Quarantine

Isolates non-compliant or compromised endpoints and triggers automatic actions like OS patching or AV updates.

Flexible Policy Enforcement

Applies customized access policies based on user, device, location, IP reputation, network zone etc. through various enforcement points.

Microsegmentation Capabilities

Segment networks dynamically based on endpoint attributes and defines granular access rules for each segment.

Integration with Network Infrastructure

Interfaces with network devices like firewalls, VPNs, proxies, routers etc. to transform access decisions into enforced controls.

Key Considerations When Evaluating NAC Solutions

Here are some critical aspects to analyze when comparing NAC system options:

Deployment Models Supported

Assess support provided for on-premise, cloud-delivered or hybrid NAC implementations.

Endpoint Platform Coverage

Validate NAC agents are available for all endpoint platforms like Windows, macOS, iOS, Android, Chromebooks etc.

Alignment to Zero Trust Philosophy

Review if NAC design matches Zero Trust tenets around least privilege access, continuous verification etc.

Microsegmentation Capabilities

Examine whether dynamic network segmentation, isolation of risky workloads and granular access policies are enabled.

Automation and Orchestration

Evaluate support for automating policy definition, endpoint onboarding, threat response workflows through APIs and integrations.


Verify through customer deployments and vendor documentation that the solution scales seamlessly to support enterprise-level endpoint volumes.

Total Cost of Ownership

Review direct licensing, deployment and ongoing operational costs. Compare TCO with competing solutions.

Analyst and Peer Ratings

Leverage Gartner Magic Quadrant, customer feedback and peer reviews to validate product capabilities and suitability.

The Bottom Line

As enterprise networks become more diverse and distributed across cloud and mobile endpoints, unrestricted network access poses tremendous risk. NAC allows organizations to enable business mobility and BYOD adoption while ensuring only compliant and authorized users and devices can access network resources.

Forrester Research predicts, "Investing in NAC solutions that provide visibility, analysis, and policy enforcement will soon become a necessity for firms." By leveraging NAC as a foundational Zero Trust control, companies can secure their networks for the digital business era.

Written by