The System.Web.Security.UrlAuthorizationModule determines whether the current user is permitted access to the requested URL, based on the user System.Security.Principal.IIdentity.Name or the list of roles that a user is a member of. For information about how the user name is determined, see ASP.NET Authentication. For information about how to manage user roles, see Managing Authorization Using ASP.NET Roles.

Authorization for a user or a role is managed using the authorization configuration element. You can allow or deny a user or a role using the allow or deny subelements, respectively. The allow and deny subelements are interpreted in the order they appear in the configuration. Once an element specifies that access is allowed or denied, the System.Web.Security.UrlAuthorizationModule completes its authorization check. For example, the following authorization section from a Web.config file requires users to log on (by denying anonymous users), and then allows only users in the Administrators role to have access. Users not in the Administrators role are denied.

<authorization>
  <deny users="?" />
  <allow roles="Administrators" />
  <deny users="*" />
</authorization>

A user or role must be specifically denied to refuse the user or role permission to a URL. That is, if the previous example had not specified the <deny users="*" /> element, then all authenticated users would have been allowed access to the requested URL, regardless of what role they were a member of.