用asp脚本实现限制IP访问

cookies跨不了域很麻烦,有了这个脚本就方便多了.
<%
ip=Request.ServerVariables("REMOTE_ADDR")
set Fso=CreateObject("Scripting.FileSystemObject")
Set Files=Fso.OpenTextFile(server.mappath("./ip.txt"),1,false)
data=files.readall
files.close
set fso=nothing
if InstrRev(data, ip, -1, 0) = 0 then
set Fso=CreateObject("Scripting.FileSystemObject")
Set File=Fso.OpenTextFile(server.mappath("./ip.txt"),8,true)
file.writeline ip
file.close
set fso=nothing
response.write "此IP今天第一次访问该页面"
response.end
else
response.write "此IP以前访问过了"
response.end
end if
%>