asp 读文件 比较ip

<%
Dim UserIPAddress
Set UserIPAddress = Request.ServerVariables("HTTP_X_FORWARDED_FOR")
If UserIPAddress = "" Then
  UserIPAddress = Request.ServerVariables("REMOTE_ADDR")
End If
If UserIPAddress <> "" Then
  Dim ipArr,flag,fso,f
  ipArr = split(UserIPAddress,".")
  UserIPAddress = ipArr(0) + "." + ipArr(1) + "." + ipArr(2) 
  flag = 0
  set fso=server.CreateObject("Scripting.FileSystemObject")
  Set f =  fso.OpenTextFile(Server.MapPath("1.txt"),1)  
    Do  While  Not  f.AtEndOfStream    
     'response.write f.readline
      If UserIPAddress = f.readline Then
         flag = 1
         exit do
      End If
    loop
    f.close
    set f=nothing
    set fso=nothing
   If flag = 1 Then
     Server.Execute("a.asp")
   else
     Server.Execute("b.asp")
   End If
End If
%>