<%
Dim ValidEntry ' Log variable
' First set that this log is valid
ValidEntry = True

' If Session Variable "LogIn" is not empty
' that mean this person has already been logged
' then set ValidLog to False
If not IsEmpty(Session("LogIn")) then ValidEntry = False

' Here you can add different restriction
' If the refering url is from same site
' don't write to log file
If Left(Request.ServerVariables("HTTP_REFERER"), 17)
="http://jb51.net" Then
ValidEntry = False
End if
If Left(Request.ServerVariables("HTTP_REFERER"), 21)
="http://www.dbjr.com.cn" Then
ValidEntry = False
End If

' Now if ValidEntry is True then enter to log file
If ValidEntry Then
Const ForAppending = 8
Const Create = true
Dim FSO
DIM TS
DIM MyFileName
Dim strLog

MyFileName = Server.MapPath("MyLogFile.txt")
Set FSO = Server.CreateObject("Scripting.FileSystemObject")
Set TS = FSO.OpenTextFile(MyFileName, ForAppending, Create)

' Store all required values in strLog
strLog = "<br><P><B>" & now & "</B> "
strLog = strLog & Request.ServerVariables("REMOTE_ADDR") & " "
strLog = strLog & Request.ServerVariables("HTTP_REFERER") & " "
strLog = strLog & Request.ServerVariables("HTTP_USER_AGENT") & "<BR>"
' Write current information to Log Text File.
TS.write strLog
TS.Writeline ""
' Create a session varialbe to check next time for ValidEntry
Session("LogIn") = "yes"
Set TS = Nothing
Set FSO = Nothing
End If
%>