Group Policy Central

I have seen an number of posts form IT Administrators on the Microsoft Group Policy forums asking how prevent their users from connecting to a wireless network. Maybe it is because they have an open WIFI network on the floor above that users keep connecting to so they can by pass the proxy server URL restrictions or they don’t want their users from accessing the internet from well known WIFI hot spots.

In the tutorial below I am going to show you how to block your laptops from connecting to specific wireless networks with the example SSID of “dlink”. This black list method is useful when you want to prevent users from connecting to networks such as “Free Public WiFi” which is nothing more than a trap set by hacker to steal people’s passwords.

Then I will go through the way will to block all wireless networks except for one called “private_ab” using the White List method. This is very useful if you only want your users to connect to wireless network you know are safe to use.

Lastly I will then quickly show you how to totally disable your wireless adapter from being able to connect to any networks.

The instructions below are specific to Vista and Windows 7 as there were a whole heap of new group policy settings that were introduced back when Vista was released.

How to Black List/White List Wireless Networks using Group Policy

Note: Steps 1 to 5 are common for setting up both black and white lists. Then the process branches and describes how to setup a black list then white list in steps 6 & 7.

Step 1. This is a computer based setting so edit a Group Policy Object (GPO) that is targeted to all the laptops in your network

Step 2. Navigate to Computer Configuration > Policies > Windows Settings > Security Settings > Wireless Network (IEEE 802.11) Policies

Step 3. Click on “Action” in the menu and then click on “Create A New Wireless Network Policy for Windows Vista and Later Releases”.

Note: You can only create one Windows Vista and later and one Windows XP wireless setting within each GPO.

Step 4. Now give the give the setting a Policy Name and Description. Ensure that the “Use Windows WLAN AutoCOnfig service for clients” is ticked so that Windows does not allow third-party software to control the wireless network adapter (e.g. Intel Wireless LAN configuration Tool).

Step 5. Now click on the Network Permission Tab and click “Add…”

Setting up a Wireless Network Black List using Group Policy

Step 6. Type in the name of the SSID you want to black list (e.g. “dlink”) then select the type of Network Type (e.g. Infrastructure) and select "Deny” from the Permission type then click “OK”

Step 7. Click “OK”

Now the user views all the wireless network the will no longer be able to connect the network that has been configured as Deny. (e.g. “dlink”)

Setting up a Wireless Network White List using Group Policy

Step 6. Type in the name of the SSID you want to white list (e.g. “private_ab”) then select the type of Network Type (e.g. Infrastructure) and select "Allow” from the Permission type then click “OK”

Step 7. Tick “Prevent connections to ad-hoc networks” and tick “Prevent connections to infrastructure networks” then click “OK”

Now you will ONLY be able to connect to the wireless network called “private_ab” and all other networks will be denied.

Note: Configuring a white list will not configure a wireless profile to connect to the allowed network, it simple allows the user to configure a profile for that particular SSID.

How to disable your wireless networks access via Group Policy

Now if you want to totally deny you users from connecting to any network profile just skip step 6. from the White List procedure leave the “Prevent connections to ad-hoc networks” and “Prevent connections to infrastructure networks”.

You users will no longer be able to connect to any wireless networks and when they click on the network in they will receive the message “Your network administrator has blocked you from connecting to this network”.

Note: Any network profile you have configured in the General tab will be automatically added as an allowed network having the two “Prevent connections” options tick will ensure that the user will not be able to connect to anything but your corporate wireless network.

Back to another profile setting this week and this one can save any organisation using Windows Vista or greater a lot of time if you manual provision your accounts. The setting is called “Set roaming profile path for all users logging onto this computer” and it configures the users roaming profile path that is normally configured on a per account basis in Active Directory Users and Computers (see below). Being able to apply this setting via Group Policy means it is one more user attribute that you no longer need to configure on the users account. This of course makes provisioning users account just that little bit simple which should save both time and the possibility for human errors.

This setting can be found under Computer Configuration > Policies > Administrative Templates > System > User Profiles but as its a computer based setting this also means that you need to be careful how you apply this setting. Applying this setting to laptop could be undesired as they may try to log into a remote location with a slow WAN link to the profile server. So if you do apply this to the laptop you might want to configured it to point to a DFS namespace path or a DNS alias (if you have subnet masking filtering enabled) which can help point them to a faster more local path. This of course means it would be really useful to have a OU structure that separate your laptops from your desktop computer.

But I would definitely recommend use this setting if you are using Windows Vista or Windows 7 in your SOE.

Windows has a cool feature that allows you to tell if your computer has Internet connectivity when you are connected to a network (see image below). This feature is called Network Connectivity Status Indicator (NCSI) it uses a combination of DNS and/or HTTP look ups to tell if you are connected to the Internet. The way does this is either via a HTTP request for http://www.msftncsi.com/ncsi.txt or a DNS look up for dns.msftncsi.com that resoles to 131.107.255.255

Windows 7

However if you find this error message really annoying there is now a Windows 7 group policy will turn it off. This is a machine setting so edit a Group Policy Object that is applied to all the workstations you want to turn this message off. Then navigate to Computer Configuration > Policies > Administrative Templates > Network Connections and enabled the “Do not show the “local access only” network icon” policy setting.

TADA… Now you will no longer see the exclamation icon on the network icon.

For more information on how NCSI works and this Windows 7 policy see http://technet.microsoft.com/en-us/library/ee126135(WS.10).aspx

Windows Vista

Unfortunately Windows Vista does not have the same Group Policy however there is a registry key that can be applied using Group Policy Preferences that has the same affect.

Key: HKLM\SYSTEM\CurrentControlSet\Services\NlaSvc\Parameters\Internet
Value: EnableActiveProbing
Data: 1 (REG_DWORD) = Enabled
Data: 0 = Disabled

Step 1. Edit a Group Policy Object that is applied to all the workstation you want this Browser Ballot disabled.

Step 2. Navigate to Computer Configuration > Preferences > Windows Settings > Registry and create a “New Registry Item”

Step 3. Type “SYSTEM\CurrentControlSet\Services\NlaSvc\Parameters\Internet” in the Key Path then type “EnableActiveProbing” in the Value name, then select REG_DWORD as the value type “0” in the value data and then click “OK”.

For more information on how NCSI works and this Windows Vista policy see http://technet.microsoft.com/en-us/library/cc766017(WS.10).aspx