78 CHAPTER 7: CONTROLLING AND MONITORING WEB ACCESS You can configure your network into subnets and assign specific clientmachine MAC addresses to be provided IP addresses within specificsubnets by DHCP. You can then prevent specific subnet IP addressranges from accessing the Web through the Webcache through WebClient Blocking.For example, you configure your user group A to use a subnet definedas 10.1.2.0-255, and group B to use another subnet defined as10.1.3.0-255. If you want to prevent group B from accessing the Web,you would add the subnet 10.1.3.0-255 to the Web Client Blockingconfiguration. Group B would then be unable to access the Web,while group A would have access. You can configure your DHCP server to return specific IP addressesbased on the requesting client machine’s MAC address. You canconfigure Web Client Blocking to block either specific client machineIP addresses, or ranges of IP addresses, as appropriate.Configuring WebClient BlockingTo configure Web Client Blocking using the Web interface:1 Log in to the Web interface.2 Click Device View on the Toolbar.3 Select System -> Caching -> Client Machine Blocking in theNavigation Tree.4 Check Block Access From All Web Clients to enable Web Client Blocking.5 In the Except these IP Addresses field, type the IP addresses or IP addressranges of the client machines that you want to allow access and clickAdd.ExampleYou can enter 216.115.105.2-217.115.105.2 to allow access for that IPaddress range, or enter 216.115.105.2 to allow access for that IPaddress. Separate individual ranges or addresses with a comma.CAUTION: If the browser on the client machine that you are using toconfigure the Webcache is also using the Webcache as a proxy, and youenable Web Client Blocking, you must ensure that you add the clientmachine to the Except these IP Addresses field. If you do not do this,access from the client machine to the Webcache will be blocked,
