Introduction Of Network Access Control

In today's interconnected world, corporations face increasingly difficult issues in safeguarding their networks. Network Access Control (NAC) is a vital cyber security approach that protects sensitive data and ensures that only authorized devices and users have access to a network.

Network Access Control is a security solution that uses a set of protocols to keep unauthorized users and devices out of a private network or give restricted access to the devices which are compliant with network security policies. It is also known as Network Admission Control. NAC ensures that only users who are authenticated and devices that are authorized and compliant with security policies can enter the network.

Key Components of Network Access Control:

1. Client 

Endpoint systems or clients are key components of network access control. These are the most common windows for network access, data exchange, and generally any kind of computing activity.

2. Client software 

It is a specific application or set of applications that are identified as an access gateway to the entire computing system. In these cases, the client’s software application is also considered part of the network access control architecture, actively participating in authentication and security enforcement processes. 

3. Authentication server 

The authentication server is one of the core components of network access control. It is typically a physical server that validates the credentials of the client device or client software requesting access. In most network access control solutions, these credentials are validated based on a list of named entities like usernames, passwords, and digital certificates.

4. Authenticator 

It is responsible for facilitating the authentication between the client and the authentication server. It comprises a managed switch or access point that securely relays credentials between components 1, 2 and 3, ensuring that a port continues to be labelled as an unauthorized state until the authentication occurs. The authenticator is also responsible for changing the port’s state to “authorized” once the server has given a green light.

5. Authentication framework 

It is considered as the language in which credentials are shared among the client device, the client software, the authentication server, and the authenticator. It differs from one solution to another. It can be used as the framework if you need to configure multiple authentication methods into the system.

6. Quarantine 

Quarantine is a sandbox environment where traffic carrying non-authenticated credentials is placed, awaiting remediation. It is a network access control component only in post-admission network access control, where authentication and security policies are enforced within the network once the user or device has already obtained access. The quarantine allows for business activity within the environment without interacting with or damaging external files. 

7. Guest networks 

Organizations might implement a dedicated guest network to isolate all third-party traffic. This is relevant for enterprises operating with a large non-payroll workforce and multiple third-party stakeholders such as regulatory bodies, consultants, vendors, etc. Guest networks are a common component governs remote access by third parties. 

8. Corporate networks 

This is the primary channel for communication in the enterprise, allowing authorized traffic as validated by the authentication server. The corporate network could be secured by additional intermittent security policies such as time-bound access that revokes authorization once a specific time or access threshold is reached.

9. Public internet 

In addition to guest networks and corporate networks, the public internet can also be used to access enterprise assets, subject to certain constraints and authentication protocols. Public internet traffic flows only through guest gateways and not via the corporate network. 

10. Management console 

Network access control can be managed through a security dashboard hosted either on-premise or on the cloud. The dashboard enables device visibility, allows for security policy configurations, maps trends or analytics, displays security alerts etc. The management console can be accessed as a web portal, a desktop app, a mobile app, or on a virtual machine, as required. 

11. Client agent 

Client agents are an optional component of network access control.

Working method of Network Access Control

Device Authentication

When a device attempts to connect to the network, NAC initiates device authentication to verify its identity. This process ensures that only authorized devices gain access.

User Authentication:

NAC may also involve user authentication to confirm the identity of the individual attempting to connect. This can include username/password verification or more advanced authentication methods like multi-factor authentication.

Security Policy Evaluation:

NAC evaluates the connecting device against predefined security policies. These policies may include criteria such as antivirus software presence, operating system updates, and adherence to specific security standards.

Health Checks:

NAC conducts health checks on the device to assess its overall security posture. This includes checking for the latest software updates, patches, and the absence of malware.

Access Decision:

Based on the results of authentication, policy evaluation, and health checks, NAC makes an access decision. Authorized and compliant devices are granted access to the network, while non-compliant or unauthorized devices may be restricted or directed to remediation.

Enforcement Mechanisms:

NAC utilizes enforcement mechanisms to implement access decisions. This may involve adjusting firewall rules, VLAN assignments, or other network parameters to enforce the defined security policies.

Continuous Monitoring:

NAC often includes continuous monitoring of connected devices. If a device’s compliance status changes during its connection (e.g., due to malware detection), NAC can dynamically adjust access privileges or initiate remediation processes.

Logging and Reporting:

NAC systems log access events and generate reports. This provides administrators with visibility into network activities, compliance status, and any security incidents that may occur.

Types of Network Access Control

Pre-admission

Pre-admission network access control occurs before access is granted. A user attempting to enter the network makes a request to enter. A pre-admission network control considers the request and provides access if the device or user can authenticate their identity.

Post-admission

Post-admission network access control is the process of granting authorization to an authenticated device or user attempting to enter a new or different area of the network to which they have not been granted authorization. To receive authorization, a user or device must verify their identity again.

Advantages of Network Access Control

Enhanced Security - Only authorized and compliant devices can access the network. Reduces the risk of unauthorized access and potential security breaches.

Policy Enforcement - Consistently enforces security policies across the network infrastructure.

Improved Visibility - Provides better visibility into network activities, facilitating quicker detection and response to security incidents.

Isolation of Non-Compliant Devices - Streamlines the identification and isolation of non-compliant or compromised devices, bolstering the network’s resilience against cyber threats.

Access Control Flexibility - Provides flexibility in defining access controls based on user roles, device types, and other criteria.

Guest Network Security - Ensures secure access for guests and visitors by implementing temporary and restricted network access.

Network Efficiency - Improves network efficiency.

Disadvantages of Network Access Control

Complex Implementation - Implementing NAC systems can be complex and require careful planning, testing, and integration with existing network infrastructure.

Initial Costs - Upfront costs are associated with acquiring and deploying NAC solutions, including hardware, software, and training expenses.

User Experience Impact - Strict access controls may sometimes impact the user experience, leading to potential frustration and productivity issues.

Guest Access Management - Managing secure guest access while maintaining a seamless user experience can be challenging and requires careful configuration.

Conclusion

Network Access Control (NAC) has evolved into an essential component of modern network security. By ensuring that only authorized users and compliant devices have access, NAC improves security, eliminates risks, and gives enterprises the visibility they need to secure their digital assets.