<%
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://devasp.com" Then
ValidEntry = False
End if
If Left(Request.ServerVariables("HTTP_REFERER"), 21)="http://www.devasp.com" Then
ValidEntry = False
End If

' Now if ValidEntry is True then enter to log file