You have many ways to control the web services access

1-      controls by user ipaddress "simple way"

2-      add user name & password parameter in all the methods to control the access and the users privialge

3-      "not test" check the iis with domain control

Hi,

You can use Ajax Authentication Service to check the authentication in web service. That maybe what you want.

http://www.asp.net/AJAX/Documentation/Live/Tutorials/UsingFormsAuthenticationTutorial.aspx