Wireless LAN Service Overview

Article
07/03/2012

Applies To: Windows Server 2008

The Wireless LAN service is a feature in this version of Windows Server that you can use to enable the wireless WLAN Auto Configuration service, and to configure WLAN AutoConfig for automatic startup. Once enabled, WLAN AutoConfig dynamically selects the wireless network to which the computer will automatically connect, and configures the necessary settings on the wireless network adapter. This includes automatically selecting and connecting to a more preferred wireless network when one becomes available.

Wireless LAN Service and WLAN AutoConfig Service

The Wireless LAN Service is a feature in this version of Windows Server that configures the WLAN AutoConfig service to start automatically, regardless of whether the computer has any IEEE 802.11 wireless adapters installed. When enabled, WLAN AutoConfig enumerates every wireless network adapter installed on the computer, manages IEEE 802.11 wireless connections, and manages the wireless connection profiles that contain the settings required to configure a wireless client to connect to a wireless network. WLAN AutoConfig allows you to connect to an existing wireless network, change wireless network connection settings, configure a connection to a new wireless network, and specify preferred wireless networks. WLAN AutoCofig also notifies you when new wireless networks are available. When you switch wireless networks, WLAN AutoConfig dynamically updates your wireless network adapter settings to match the settings of that new network and a network connection attempt will be made.

If you are connecting to a wireless network for the first time, WLAN AutoConfig will configure basic network settings, if the service is enabled. However, you might need to configure additional settings, such as the data encryption type or network key, if they are not automatically configured for your account through the Wireless Network (IEEE 802.11) Policies in Active Directory. You might also need to request account permissions from your network administrator.

Enabling and Starting WLAN AutoConfig

There are several methods to enable and start the WLAN AutoConfig service on client computers running this version of Windows Server or Windows Vista:

The New Features Wizard

Configure Wireless LAN Service in the New Features Wizard in this version of Windows Server.
Wireless Network (IEEE 802.11) Policy

Enable the Windows Vista Wireless Network (IEEE 802.11) Policy setting, Use the WLAN AutoConfig Service for clients. In the properties of the Windows Vista Wireless Network (IEEE 802.11) Policy, on the General tab, select Use Windows to configure wireless network settings for clients.

This setting enables administrators to specify that the WLAN AutoConfig Service is used to configure and connect wireless clients running Windows Vista or this version of Windows Server to the wireless network.
Netsh WLAN set autoconfig

Use the netsh wlan set autoconfig command using the following syntax:

set autoconfig enabled={yes|no} **interface=**InterfaceName

You can use Netsh wlan commands to configure the local computer, or to configure multiple computers by using a logon script.
In the Services Microsoft Management Console (MMC) snap-in.

Navigate to WLAN AutoConfig Service, the modify the properties of the service to meet your requirements.

Changes in the wireless auto configuration

This version of Windows Server and Windows Vista® include the following changes to wireless auto configuration:

Changes in the wireless auto configuration service name

Windows Server 2003 and Windows XP	This version of Windows Server and Windows Vista
Wireless auto configuration service name: Wireless Zero Configuration service (WZCSVC)	Wireless auto configuration service name: WLAN AutoConfig service (XXX)

Wireless auto configuration service name:

Wireless Zero Configuration service (WZCSVC)

Wireless auto configuration service name:

WLAN AutoConfig service

(XXX)

Wireless auto configuration details for broadcasting and non-broadcasting wireless networks

Note

In wireless broadcasting networks, the wireless network name or Service Set Identifier (SSID) is included in the Beacon frames sent by the wireless access point (AP). In non-broadcasting networks, the Beacon frame value for SSID is set to NULL.

Windows Server 2003 and Windows XP	This version of Windows Server and Windows Vista
In Windows XP and Windows Server 2003, the Wireless Zero Configuration service attempts to match wireless networks that are broadcasting their network name with preferred wireless networks profiles that are configured on the computer. If there are no available networks that match a preferred wireless network profile, then WZCSVC sends probe requests to determine if any preferred networks in the ordered list are non-broadcast networks. The result is that the computer connects to broadcast networks before non-broadcast networks, regardless of whether a non-broadcast network is ranked higher in the preferred list than a broadcast network. Additionally, Windows XP and Windows Server 2003 wireless clients advertise their list of preferred wireless networks when sending probe requests.	In this version of Windows Server and in Windows Vista, you can configure wireless network configuration profiles as broadcast or non-broadcast wireless networks. The result is that WLAN AutoConfig attempts to connect to wireless networks in order they are ranked in the list of preferred networks, regardless of whether they are broadcast or non-broadcast networks. Because the wireless networks are explicitly marked as broadcast or non-broadcast, wireless clients running Windows Server and Windows Vista send only probe requests for non-broadcast wireless networks.

In Windows XP and Windows Server 2003, the Wireless Zero Configuration service attempts to match wireless networks that are broadcasting their network name with preferred wireless networks profiles that are configured on the computer. If there are no available networks that match a preferred wireless network profile, then WZCSVC sends probe requests to determine if any preferred networks in the ordered list are non-broadcast networks.

The result is that the computer connects to broadcast networks before non-broadcast networks, regardless of whether a non-broadcast network is ranked higher in the preferred list than a broadcast network.

Additionally, Windows XP and Windows Server 2003 wireless clients advertise their list of preferred wireless networks when sending probe requests.

In this version of Windows Server and in Windows Vista, you can configure wireless network configuration profiles as broadcast or non-broadcast wireless networks.

The result is that WLAN AutoConfig attempts to connect to wireless networks in order they are ranked in the list of preferred networks, regardless of whether they are broadcast or non-broadcast networks.

Because the wireless networks are explicitly marked as broadcast or non-broadcast, wireless clients running Windows Server and Windows Vista send only probe requests for non-broadcast wireless networks.

Behavior changes for no available preferred wireless networks

In Windows XP and Windows Server 2003, if a preferred wireless network cannot be connected and the wireless client is configured to prevent automatic connection to wireless networks that are not in the preferred list (the default), Wireless Auto Configuration creates a random wireless network name and places the wireless network adapter in infrastructure mode. However, the random wireless network does not have a security configuration, making it possible for a malicious user to connect to the wireless client using the random wireless network name. The new Wireless Client Update for Windows XP with Service Pack 2 modifies this behavior by configuring the wireless network adapter with a random name and a security configuration consisting of a 128-bit random encryption key and the strongest encryption method supported by the wireless network adapter. This new behavior helps prevent a malicious user from connecting to the wireless client using the random wireless network name.

For computers running this version of Windows Server" or Windows Vista that use updated wireless drivers designed for Windows Vista, the wireless WLAN AutoConfig service places the wireless network adapter in a passive listening mode to remove the vulnerability that effects computers running Windows XP and Windows Server 2003. While in the passive mode, the wireless network adapter will not send Probe Request frames for a random wireless network name or any other name; malicious users cannot connect to the wireless client.

Note
Most wireless network drivers have been updated for Windows Vista. If you are using a wireless network adapter driver that was designed for Windows XP, computers running Windows Vista or this version of Windows Server will use the behavior of the Wireless Client Update for Windows XP with Service Pack 2 (a random wireless network name with a security configuration).