登陆页login.asp:

<%
if request.Form.count>0 then
session("username")=request("username")
application(session("username"))=session.SessionID
response.Redirect("index.asp")
end if
%>
<form method=post action="">
<input type="text" name="username"><input type="submit">
</form>

其他需要认证的页面index.asp:

<%
if application(session("username"))=session.SessionID then
response.Write("已经登陆")
else
response.Write("没有登陆")
end if
%>