allow Element for authorization (ASP.NET Settings Schema)

Adds an authorization rule that allows access to a resource to the mapping of authorization rules.

<allow 
   users="comma-separated list of users"
   roles="comma-separated list of roles"
   verbs="comma-separated list of verbs"
/>

Attributes and Elements

The following sections describe attributes, child elements, and parent elements.

Attributes

Attribute	Description
users	Required String attribute. A comma-separated list of user names that are denied access to the resource. A question mark (?) denies anonymous users and an asterisk (*) indicates that all users are denied access.
roles	Required String attribute. A comma-separated list of roles that are denied access.
verbs	Optional String attribute. A comma-separated list of HTTP transmission methods that are granted access to the resource. Verbs that are registered to ASP.NET are GET, HEAD, POST, and DEBUG.

Child Elements

None.

Parent Elements

Element	Description
configuration	Specifies the required root element in every configuration file that is used by the common language runtime and the .NET Framework applications.
system.web	Specifies the root element for the ASP.NET configuration settings in a configuration file and contains configuration elements that configure ASP.NET Web applications and control how the applications behave.
authorization	Configures the authorization for a Web application. The authorization tag controls client access to URL resources. This element can be declared at any level (machine, site, application, subdirectory, or page).

Remarks

The allow element adds an authorization rule that allows access to a resource to the mapping of authorization rules that are stored in the authorization element.

The authorization element configures the authorization for a Web application, by controlling client access to URL resources. For the required attributes, you can use either the users or roles attribute or both.

At run time, the authorization module iterates through the allow and deny elements, starting at the most local configuration file, until the authorization module finds the first access rule that fits a particular user account. Then, the authorization module grants or denies access to a URL resource depending on whether the first access rule found is an allow or a deny rule. The default authorization rule is <allow users="*"/>. Thus, by default, access is allowed unless configured otherwise.

In order to facilitate deployment, the period (.) shortcut notation for the current computer is supported. This allows you to prefix each user or role with a period and a backslash (.\) sequence, as shown in the following code example:

<allow roles=".\roleName"/>

<allow users=".\userName"/>

At run time the period-backslash sequences are substituted with "localmachinename\" sequences. The substitution is done only if a Windows identity is being used with the request. This is to avoid conflicts when the period-backslash sequences are used in arbitrary roles with custom principals.

Because the authorization element does not represent a collection, there are no clear or remove child elements. To programmatically clear the mappings of authorization rules, use the Clear or Remove method.

Default Configuration

The following default authorization element is configured in the root Web.config file in the .NET Framework version 2.0 and configured in the Machine.config file in the .NET Framework versions 1.1 and 1.0.

<authorization>
   <allow users="*" />
</authorization>

Example

The following code example demonstrates how to deny access to all user accounts and allows access to all members of the role admins.

<configuration>
  <system.web>
    <authorization>
      <allow roles="admins"/>
      <deny users="*"/>
    </authorization>
  </system.web>
</configuration>

Element Information

Configuration section handler	AuthorizationSection
Configuration member	AuthorizationRuleCollection
Configurable locations	Machine.config Root-level Web.config Application-level Web.config Virtual or physical directory–level Web.config
Requirements	Microsoft Internet Information Services (IIS) version 5.0, 5.1, or 6.0 The .NET Framework version 1.0, 1.1, or 2.0 Microsoft Visual Studio 2003 or Visual Studio 2005

See Also

Tasks

How to: Configure Specific Directories Using Location Settings
How to: Lock ASP.NET Configuration Settings

Reference

authorization Element (ASP.NET Settings Schema)
deny Element for authorization (ASP.NET Settings Schema)
configuration Element (General Settings Schema)
system.web Element (ASP.NET Settings Schema)
System.Configuration
System.Web.Configuration

Concepts

ASP.NET Authorization
ASP.NET Configuration File Hierarchy and Inheritance
Securing ASP.NET Configuration
ASP.NET Configuration Scenarios

Other Resources

Managing Authorization Using Roles
General Configuration Settings (ASP.NET)
ASP.NET Configuration Settings
Configuring ASP.NET Applications
ASP.NET Configuration API