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Ethernet switch access with IAS

Updated: January 21, 2005

Applies To: Windows Server 2003, Windows Server 2003 R2, Windows Server 2003 with SP1, Windows Server 2003 with SP2

Ethernet switch access

This topic describes how IAS can be used to support authentication, authorization, and accounting for authenticated Ethernet switch connections to an organization. In contrast to user-authenticated connections, such as dial-up and VPN connections, Ethernet connections use computer certificates and computer authentication to validate the computer that is connecting to the Ethernet switch. This topic describes a typical configuration for an organization that uses:

  • Two IAS servers.

    Two IAS servers (one primary and one secondary) are used to provide fault tolerance for RADIUS-based authentication. If only one RADIUS server is configured and it becomes unavailable, authenticating switch clients cannot connect. By using two IAS servers and configuring all authenticating Ethernet switches (RADIUS clients) for both the primary and secondary IAS servers, the RADIUS clients can detect when the primary RADIUS server is unavailable and automatically fail over to the secondary IAS server.

  • Active Directory domains.

    Active Directory domains contain the user accounts, passwords, and dial-in properties that each IAS server requires to authenticate user credentials and evaluate both authorization and connection constraints. To optimize IAS authentication and authorization response times and minimize network traffic, IAS is installed on domain controllers.

  • A computer certificate infrastructure.

    The Extensible Authentication Protocol-Transport Level Security (EAP-TLS) authentication protocol is used with computer certificates to authenticate Ethernet connections and provide the highest level of security for authentication.

  • Ethernet switch remote access policies.

    Remote access policies are configured for authenticated switch connections so that guest switch users obtain restricted access to a virtual LAN (VLAN) that contains a certificate server and authenticated switch users obtain unrestricted access to the organization intranet.

  • Multiple authenticating switches.

    Multiple third-party Ethernet authenticating switches provide access in different buildings of an organization.

  • A certificate server on a separate VLAN for new Ethernet switch clients.

    A certificate server is placed on a separate virtual local area network (VLAN) and used by a new switch client to obtain a computer certificate for subsequent switch access. After 10 minutes of receiving a guest connection, the switch client is disconnected. When the switch client computer reconnects, it authenticates by using the newly installed computer certificate and obtains authenticated switch access to the network.

The following illustration shows an Ethernet switch configuration.

IAS as a RADIUS server

Notes

  • This topic only describes how to configure IAS. It does not describe the configuration of Active Directory domains, the certificate infrastructure, or Ethernet switches. For more information about how to deploy these components, see the appropriate Help topics.

  • This topic describes the bootstrapping of new Ethernet clients by using a VLAN that contains a certificate server. You can also bootstrap new Ethernet clients by using an unauthenticated Ethernet connection or a certificate that has been extracted to a floppy disk.

To configure IAS for this example, complete the following steps:

  • Configure Active Directory for computer accounts and groups.

  • Configure the primary IAS server on a domain controller.

  • Configure the secondary IAS server on a different domain controller.

  • Configure RADIUS authentication and accounting on Ethernet switches.

Configuring computer accounts and groups

To configure computer accounts and groups, do the following:

  1. Ensure that all computers that are making authenticating switch connections have a corresponding computer account.

  2. If you want to manage switch access by group, set the remote access permission on computer accounts to Control access through Remote Access Policy. For more information, see Configure remote access permission for a user.

  3. Organize switch access computers into the appropriate universal and nested groups in order to take advantage of group-based remote access policies. For example, create a universal group named SwitchComputers that contains global groups of switch computer accounts. For more information, see Group scope.

  4. Configure the domain in which the IAS server computers are members for the auto-enrollment of computer certificates. For more information, see Configure automatic certificate allocation from an enterprise CA.

  5. Configure the Guest account to allow guest access for new Ethernet clients. For more information, see Guest authentication. Enable reversibly encrypted password storage on the Guest account. For more information, see User and computer accounts.

  6. Create a group named Guests, and add the Guest account as a member. For more information, see Create a new group.

Configuring the primary IAS server on a domain controller

To configure the primary IAS server on a domain controller, do the following:

  1. On the domain controller, install IAS as an optional networking component. For more information, see Install IAS.

  2. Configure the IAS server computer (the domain controller) to read the properties of user and computer accounts in the domain. For more information, see Enable the IAS server to read user accounts in Active Directory.

  3. If the IAS server authenticates connection attempts for user and computer accounts in other domains, verify that the other domains have a two-way trust with the domain in which the IAS server computer is a member. Next, configure the IAS server computer to read the properties of user and computer accounts in other domains. For more information, see Enable the IAS server to read user accounts in Active Directory. For more information about trust relationships, see Trust direction.

    If the IAS server authenticates connection attempts for user and computer accounts in other domains, and those domains do not have a two-way trust with the domain in which the IAS server computer is a member, see Authentication across forests.

  4. Enable file logging for accounting and authentication events. For more information, see Configure log file properties.

  5. If needed, configure additional UDP ports for authentication and accounting messages that are sent by RADIUS clients. For more information, see Configure IAS port information. By default, IAS uses UDP ports 1812 and 1645 for authentication and ports 1813 and 1646 for accounting.

  6. Add the authenticating Ethernet switches as RADIUS clients of the IAS server. For more information, see Add RADIUS clients. Verify that you are configuring the correct name or IP address and shared secrets. For more information, see Shared secrets. Enable the use of the Message Authenticator attribute only when it is supported by the Ethernet switch.

  7. Use the New Remote Access Policy Wizard to create a common Ethernet policy with the following settings:

    • Policy name: Ethernet switch access

    • Access Method: Ethernet

    • User or Group: Select Group, and then specify the SwitchComputers group (example).

    • Authentication methods: Select Smart Card or other Certificate. If you have multiple computer certificates, click Configure, and then select the appropriate computer certificate.

  8. If you are using certificate-based authentication, you can use the New Remote Access Policy Wizard to create a custom Ethernet switch policy with the following settings:

    • Policy name: New switch access

    • Conditions: NAS-Port-Type matches Ethernet and Windows-Groups matches Guests

    • Permission: Grant remote access permission

    • Profile settings, Dial-in Constraints tab: Select the Minutes client can be connected check box, and then type 10.

    • Profile settings, Authentication tab: Select Extensible Authentication Protocol and the MD-5 Challenge EAP type, and then clear all other check boxes.

    • Profile settings, Advanced tab: Add the Tunnel-Type attribute with the value of Virtual LANs (VLAN); Add the Tunnel-Pvt-Group-ID attribute with the value of the VLAN ID that corresponds to the VLAN that contains the certificate server for new switch clients.

    For additional examples of remote access policies, see Remote Access Policies Examples.

  9. Delete the default remote access policies, or ensure that they are the last policies to be evaluated. For more information, see Delete a remote access policy and Change the policy evaluation order.

Configuring the secondary IAS server on a different domain controller

To configure the secondary IAS server on a different domain controller, do the following:

  1. On the other domain controller, install IAS as an optional networking component. For more information, see Install IAS.

  2. Configure the secondary IAS server computer (the other domain controller) to read the properties of user accounts in the domain. For more information, see Enable the IAS server to read user accounts in Active Directory.

  3. If the secondary IAS server authenticates connection attempts for user accounts in other domains, verify that the other domains have a two-way trust with the domain in which the secondary IAS server computer is a member. Next, configure the secondary IAS server computer to read the properties of user accounts in other domains. For more information, see Enable the IAS server to read user accounts in Active Directory. For more information about trust relationships, see Trust direction.

    If the secondary IAS server authenticates connection attempts for user accounts in other domains, and those domains do not have a two-way trust with the domain in which the secondary IAS server computer is a member, see Authentication across forests.

  4. Copy the configuration of the primary IAS server to the secondary IAS server. For more information, see Copy the IAS configuration to another server.

Configuring RADIUS authentication and accounting on Ethernet switches

To configure your third-party Ethernet switch RADIUS client with two RADIUS servers (the primary and secondary IAS servers), see the Ethernet switch documentation.

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