You can configure Internet Information Server to grant access to specific IP addresses and subnet masks. In this way, you allow only specific users to access your Internet server. At the same time, by specifying IP addresses, you can prevent entire networks or an individual site from accessing your server. This technique is especially useful to block an address from which you have logged a volume of suspicious activity.
Internet Information Server checks the source IP address of every received packet against the settings you specified on the Advanced tab of the WWW Service Properties dialog box. You can use that dialog box to set separate IP address access restrictions for each Internet Information Server service.
Note
If your Internet server is attached to a proxy server or firewall, your source IP address emanates from the proxy server or firewall. In such cases, your filter must distinguish an external source IP address from the source IP address of your firewall or proxy server. Set your system to log and restrict any incoming packet with an external source IP address that exactly matches your internal proxy server and firewall source address. Such packets usually indicate that an Internet user is "spoofing" (mimicking) your source IP address in an attempt to gain access to your network.