Manual Access control in ASP .Net

[Gundemci]

Is there a way I can restrict access to pages without the built in role based way?Essentially if the user tries to access admin.aspx then it redirects to \[code\]login.aspx&redirect_url=admin.aspx\[/code\]\then, they will postback with their credentials and I will give them a session cookie and so forth.Is there an example of this?Thanks