how to set IP filtering under iis7 with C# code

i found someone registered our web site with script yesterday.

20,000 register record in our db with the same ip address

i know how to filtering ip under iis with ui 

but i want to listening record changes and filtering it with C# code

i know, in the namespace 'Microsoft.Web.Administration' 

i can use the class 'ServerManager' to find some information about iis

but i don’t find some useful information in 'ServerManager' with filtering ip