Installing Context-Aware Network Access Control using Cisco ISE Policies

Modern enterprise networks aren't static systems where simple authentication is sufficient. Businesses now require sophisticated, contextually aware access control that can continuously evaluate users' devices, their capabilities, and security practices prior to giving access. This has led to Network Access Control (NAC), an essential element of any security system.

Utilizing Cisco ISTE (Identity Services Engine), it is possible for enterprises to design and enforce sophisticated NAC rules that extend far beyond basic authentication. Through the combination of multiple policies, Cisco ISE enables an integrated approach to protect wireless, wired, or remote access networks.

In this blog, we'll examine how to configure Cisco ISE to build NAC policy, learn about the key ISE NACP parts, and then look at the policy enforcement process in real-world settings by using the learning method taken from DClessons.

Introduction to Network Access Policy in Modern Enterprises

Today's enterprises are operating in extremely dynamic settings, where users are connected across multiple locations with a variety of devices. Traditional security strategies fail to tackle:

Diversity of devices (laptops, IoT, mobiles)

Work from home and in a hybrid environment

Security conformity standards

To overcome these issues and address these challenges, companies adopt contextually-aware NAC solutions that assess:

User identity

Type of device

Security posture

Access method and location

Cisco ISE provides this capability via its Network Access Control Policy (NACP) framework.

Overview of Cisco ISE NACP

The ISE NACP (Network Access Control Policy) is a well-organized mix of several policies that work in concert to ensure secure and flexible access control.

Instead of relying on one rule, Cisco ISE evaluates multiple layers of policies to decide:

The question is whether access is appropriate to be granted

What kind of access is allowed?

What security limitations should be enforced?

This layering approach ensures the access decision is based on context and adaptable, thereby improving overall security of the network.

Core Cisco ISE NACP Components

Cisco ISE NACP consists of various policy components that together ensure access control:

1. Authentication Policy

This policy validates the identity of any users or devices trying to connect to the network. It allows:

Enterprise users

Access for guests

Device-based authentication

2. Authorization Policy

After authentication

This policy will determine the authorized actions that are allowed. For instance:

Assign VLANs

Apply ACLs

Restrict or allow certain services

Authorization policies are only enforced when a rule matches.

3. Device Profiling Policy

This policy is able to identify the type of device connected to the internet. It is passive and assists in:

Detecting devices that are not recognized

Enforcing device-specific access control

Enhancing visibility

4. Host Security Posture Assessment Policy

This policy assesses the security capabilities of the device, which includes:

Status of the antivirus

OS updates

Configuration of the firewall

In accordance with the law on compliance, access may be allowed or restricted, or even denied.

Configuring Cisco ISE to Build NAC Policy

To enable the ISE to create NAC policies, administrators utilize the ISE GUI that provides a centralized interface to manage all policies.

Typical Workflow:

Define authentication sources (e.g., AD, LDAP).

Configure authentication policies

Create authorization rules

Make sure you enable profiling and posture policies.

Test and verify the behavior of the policy

The ISE GUI makes it easier to create policies creating by permitting administrators to design rules-based logic using specific conditions or actions.

Authentication Mechanisms and MAB in ISE

Cisco ISE supports multiple authentication methods, which ensure compatibility with different types of devices.

MAC Authentication Bypass (MAB)

MAC Authentication Bypass (MAB) is utilized when devices are not able to allow 802.1X authentication, like:

Printers

IP phones

IoT devices

In MAB:

A device's MAC number is utilized to determine its identification

ISE examines its MAC with its databases

Access to information is granted or denied according to the policy

MAB is typically utilized together with 802.1X to provide a broad coverage of the network.

Policy Enforcement Phases in ISE Deployment

The deployment of NAC policies on an active network requires a gradual method to prevent disruptions.

Common Policy Enforcement Phases:

1. Monitor Mode

No enforcement

Only the ability to see devices and users

2. Low Impact Mode

Enforcement is limited

Policy testing is gradual

3. Closed Mode

Full enforcement

Only authorized users or devices gain access.

This deployment phase helps companies to reduce the risk of installing an ISE solution.

Security Domains in Cisco ISE

Security domains organize users and devices on the basis of similar risks and access conditions.

Examples:

Guest Access

Wired Network Users

Wireless Users

Remote Access

Internet Access

When they define security domains, companies can implement the same scalable policy across various networks.

Understanding ISE Authorization Rules

Authorization rules form the basis of the policy enforcement system within Cisco ISE.

Key Characteristics:

From top to bottom

The first rule of matching is used.

Decides on the final access control decision

Common Actions in Authorization Rules:

Access to the Internet is permitted or denied

Assign VLAN or ACL

Apply TrustSec SGT

Redirect to the web for authentication

Inforce checks on posture

These rules permit precise control over access to networks.

Host Security Posture Assessment in ISE

Posture assessment makes sure that only compliant and secure devices are granted network access.

Types of Posture Agents:

Temporary Agent

Installed using a browser

Limited functional

No remediation capability

Full Agent (Cisco AnyConnect)

Attached to the point of termination

Performs extensive security checks

Aids in remediation actions

Remediation Examples:

Update your antivirus

Applying OS patches

Ensuring firewall rules are enforced

All posture configurations are controlled via the ISE GUI. This makes it simpler to apply compliance guidelines.

Deploying Cisco ISE Solution in Enterprise

When installing an ISE solution, companies must be aware of:

Definition of clear security objectives

Ensure that devices are visible to the fullest extent

Integration with MDM systems

Implementing the phased deployment

Key Objectives:

Verify all devices and users

Enforce proper authorization

Corporate traffic and segment guest traffic

Find and quarantine the devices that are infected

A well-planned deployment will provide solid security with little disruption.

Benefits of Context-Aware NAC Using Cisco ISE

Cisco ISE provides multiple benefits for enterprises' networks:

Centralized policy enforcement

Increased visibility (Who is, Which, When)

Dynamic access control

Improved security compliance

Integration with other systems

It transforms conventional security networks into adaptive and intelligent security environments.

Final Thoughts

The creation of a strong Network Access Control Policy (NACP) in Cisco ISE is essential for protecting the modern-day enterprise network. Through the combination of authorization, authentication profiling, and posture analysis, Cisco ISE enables a fully contextual Access Control System.

A method of deployment that is phased in conjunction with the appropriate use of MAC authentication bypass (MAB) and clearly defined authorization rules will ensure that businesses can implement NAC without operational risk.

Through the practical lessons of DClessons, professionals learn from real-world experience when it comes to creating, configuring, and installing Cisco ISE policies that align with the security needs of enterprises.

Frequently Asked Questions (FAQs)

What are the primary elements of Cisco NACP ISE?

Cisco ISE NACP comprises authentication Policy as well as authorization Policy and Device Profiling Policy, along with Host Security Assessment Policy. These components are used together to ensure that access control is context-aware.

What exactly is MAC Authentication Bypass (MAB), and how do you use it?

MAB is a device that does not have 802.1X authentication. It relies on its MAC address to identify it and is typically used for printers, IP phones, and IoT devices.

What are the various phases of policy enforcement within Cisco ISE?

Cisco ISE supports Monitor Mode, Low Impact Mode, and Closed Mode. These modes allow for the gradual introduction of NAC policies without affecting the network.

What is the process for authorization rules inside Cisco ISE?

Authorization rules are analyzed from top to bottom. If a rule is found to be compatible, ISE applies the defined action, like the granting of access, granting VLANs, or implementing security policies.

What's the point of assessing host posture in ISE?

Host posture assessment determines whether a device complies with security requirements, such as security features like antivirus software, OS updates, and firewall settings. Unconforming devices may be denied access or remedied prior to access being granted.

You might also find these blog posts interesting:

Designing Network Access Control that is Scalable using Cisco ISE Architecture
Enterprise Network Access Control and Policy Enforcement using Cisco ISE
Secure Device Administration and Network Access Using AAA Architecture