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These step-by-step instructions and troubleshooting tips will help you set up 802.1X EAP-TLS authentication with Cisco ISE to improve the security of your wired network. Make sure to adjust the configuration steps to fit your specific network environment and security needs. If you need more help, refer to the official Cisco documentation or seek advice from a network security expert.

Demystifying Wired 802.1X EAP-TLS Configuration with Cisco ISE

Understanding the Components

Before diving into the configuration steps, let’s briefly understand the key components involved in 802.1X EAP-TLS authentication.

  • 802.1X: A port-based network access control (PNAC) protocol that provides authentication before granting access to a network.
  • EAP-TLS (Extensible Authentication Protocol – Transport Layer Security): A secure authentication method that uses digital certificates for client and server authentication.
  • Cisco Identity Services Engine (ISE): A comprehensive security policy management platform that provides authentication, authorization, and accounting (AAA) services.

Preparing the Environment

To successfully implement 802.1X EAP-TLS, ensure you have the following prerequisites in place:

  • Public Key Infrastructure (PKI): You need a functional PKI to issue and manage digital certificates for your clients and servers. This typically involves a Microsoft Certificate Authority or similar.
  • Network Devices: Your network switches and/or wireless access points should support 802.1X authentication.
  • Client Devices: Your endpoint devices (laptops, desktops, etc.) must have network interface cards (NICs) that support 802.1X. Additionally, you need to install the appropriate client certificates on these devices.

Step-by-Step Configuration

The following table outlines the step-by-step configuration process for 802.1X EAP-TLS with Cisco ISE:

1Network Device Configuration:Configure your network devices (switches/APs) to enable 802.1X authentication and specify the RADIUS server (Cisco ISE).
2Cisco ISE Configuration:
a. Add Network Devices: Add your network devices as network access devices (NADs) in Cisco ISE.
b. Certificate Configuration:
c. Policy Sets: Create policy sets to group authentication and authorization rules for different user groups or network segments.
d. Authentication Policy: Create an authentication policy rule to specify EAP-TLS as the authentication method and associate it with the certificate authentication profile.
e. Authorization Policy: Create an authorization policy rule to define the access rights (VLAN assignment, ACLs, etc.) granted to authenticated users.
3Client Device Configuration:Install the client certificate on the endpoint devices and configure the network settings to use EAP-TLS for authentication.

Troubleshooting Tips

If you encounter issues during the configuration or testing process, consider the following troubleshooting tips:

  • Check Logs: Review the logs on your network devices, Cisco ISE, and client devices for any error messages related to 802.1X authentication.
  • Certificate Validation: Ensure that the client certificates are valid and trusted by Cisco ISE.
  • Policy Configuration: Double-check your authentication and authorization policies to ensure they are correctly configured and applied.
  • Network Connectivity: Verify that there are no network connectivity issues between your client devices, network devices, and Cisco ISE.

Cisco ISE Wired 802.1X EAP-TLS Setup Basics

Deploying EAP-TLS authentication for wired networks using Cisco ISE requires careful planning. This section will guide through the critical steps and configurations necessary to secure network access.

Understanding 802.1X and EAP-TLS

802.1X authentication is a layer 2 access control protocol that enhances security on both wired and wireless networks. It uses EAP (Extensible Authentication Protocol) for message exchange during the authentication process. EAP-TLS (EAP-Transport Layer Security), specifically, is an EAP method that uses digital certificates for mutual authentication between the client and the server. In this setup, Cisco ISE acts as the authentication server, managing the certificates and credentials.

Cisco ISE Deployment Prerequisites

Before deploying Cisco ISE for EAP-TLS, ensure that the following prerequisites are met:

  • Cisco ISE: Make sure Cisco ISE is installed and set up correctly.
  • System Certificate: Obtain a system certificate for ISE from a trusted Certificate Authority (CA).
  • Network devices: Register all network access devices in ISE as network resources.

Properly configuring these elements is critical for a robust and secure EAP-TLS authentication system.

Root CA and Intermediate CAs Configuration

Certificates play a pivotal role in the EAP-TLS authentication process. Begin by configuring ISE with certificates from a trusted CA:

  1. Root CA Certificate: Import the root CA certificate into ISE. This is essential to establish trust with client certificates.
  2. Intermediate CAs: If any, also import intermediate CA certificates to complete the certification path.

On the ISE interface, navigate to Certificate Management to import and manage these certificates. Ensure the RSA keys used are strong, aligning with organizational security policies.

Through these configurations, ISE establishes a trusted foundation to authenticate users and devices on the network.

ISE EAP-TLS Authentication Configuration

When configuring ISE for EAP-TLS authentication, precision is key. This section helps guide through setting up the necessary Identity Services Engine (ISE) components for a secure, certificate-based, wired 802.1X network access control.

Defining AAA and Identity Store Settings

AAA configuration involves setting up the authentication, authorization, and accounting components to secure network access. For authentication, one typically links the ISE to an Active Directory (AD) to validate usernames and ensure they have correct permissions. This linkage involves configuring ISE as a RADIUS server to communicate with AD, and setting the RADIUS as a part of the default network access in ISE’s policy elements. Under Identity Store Sequences, one ensures ISE queries the appropriate identity stores for different types of credentials.

Configuring Authentication and Authorization Policies

Next, setting up the authentication policy is about defining how the system should handle incoming authentication requests. Here, EAP-TLS should be set as the preferred authentication method. For authorization, authorization profiles determine the kinds of permissions and access levels granted upon successful authentication. The authorization rule can use conditions based on AD group membership to dictate these permissions.

Network Device and Supplicant Settings

The last piece of the puzzle requires proper configuration of both the supplicant (the endpoint device seeking access) and the network device (such as a switch or wireless access point). The supplicant must be configured with the right client certificate and be set to use EAP-TLS. The network device needs to be added to ISE, ensuring it’s set up to enforce policies via RADIUS. The dot1x system must be enabled on these devices to facilitate EAP-TLS communication.

Implementing a secure network with ISE using EAP-TLS authentication involves meticulous configuration of AAA settings, authentication, and authorization policies, as well as the supplicant and network device settings. By carefully adhering to each step, a robust security posture can be established.

User and Endpoint Certificate Management

When setting up 802.1X EAP-TLS on a network, managing certificates for users and endpoints correctly is crucial. This involves creating profiles for certificate-based authentication and ensuring that user devices have the necessary certificates installed for secure access.

Certificate Authentication Profile Creation

For Cisco ISE to authenticate a user or a device using EAP-TLS, a Certificate Authentication Profile must be created. This profile contains the rules and conditions that the ISE server will use to validate the certificates. To start, administrators generate a Certificate Signing Request (CSR) and then receive a server certificate from a trusted Certificate Authority (CA). In the profile, specify which CA issued the user certificates, and choose what to check for, such as a specific domain user group or machine attributes.

  1. Log into ISE and navigate to Policy > Policy Elements > Authentication > Certificate Profiles.
  2. Click Add to create a new profile.
  3. Define the profile:
    • Name: Give it a descriptive name.
    • Description: Optionally describe its use.
    • Trust for CA: Choose the CA that issued the user certificates.
    • Certificate Attribute: Define which attribute, such as Subject Name or Alternative Name, the ISE should check.

User Certificate Deployment to Endpoints

Admins must deploy user and endpoint certificates to devices that will be connecting to the network. For Windows PCs, one common way to distribute these credentials is through Group Policy in a Microsoft domain environment. MAC users can have their certificates installed manually or via management tools.

For Windows:

  • Use Group Policy to push the client certificate or machine certificate to the device. This automatically installs the certificate in the user’s Personal store or the Local Machine store on the PC.
  • Ensure the certificate includes “Client Authentication” as one of its purposes.
  • Verify that endpoints are using Group Policy by running gpupdate /force in the command prompt or by restarting the machine to fetch new policies.

For MAC:

  • Manually import the user certificate using Keychain Access or deploy it via device management solutions.
  • Set the certificate to be accessible to the network access software, which can be native or any third-party application compliant with EAP-TLS.

Managing these certificates with accuracy and precision ensures that the network remains secure while users enjoy seamless access to resources.

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