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Apache Module mod_authn_core

Description:	Core Authentication
Status:	Base
ModuleIdentifier:	authn_core_module
SourceFile:	mod_authn_core.c
Compatibility:	Available in Apache 2.3 and later

Summary

This module provides core authentication capabilities to allow or deny access to portions of the web site. mod_authn_core provides directives that are common to all authentication providers.

Creating Authentication Provider Aliases

Extended authentication providers can be created within the configuration file and assigned an alias name. The alias providers can then be referenced through the directives AuthBasicProvider or AuthDigestProvider in the same way as a base authentication provider. Besides the ability to create and alias an extended provider, it also allows the same extended authentication provider to be reference by multiple locations.

Examples

This example checks for passwords in two different text files.

Checking multiple text password files

# Check here first
<AuthnProviderAlias file file1>
    AuthUserFile "/www/conf/passwords1"
</AuthnProviderAlias>

# Then check here
<AuthnProviderAlias file file2>   
    AuthUserFile "/www/conf/passwords2"
</AuthnProviderAlias>

<Directory "/var/web/pages/secure">
    AuthBasicProvider file1 file2
    
    AuthType Basic
    AuthName "Protected Area"
    Require valid-user
</Directory>

The example below creates two different ldap authentication provider aliases based on the ldap provider. This allows a single authenticated location to be serviced by multiple ldap hosts:

Checking multiple LDAP servers

<AuthnProviderAlias ldap ldap-alias1>
    AuthLDAPBindDN cn=youruser,o=ctx
    AuthLDAPBindPassword yourpassword
    AuthLDAPURL ldap://ldap.host/o=ctx
</AuthnProviderAlias>
<AuthnProviderAlias ldap ldap-other-alias>
    AuthLDAPBindDN cn=yourotheruser,o=dev
    AuthLDAPBindPassword yourotherpassword
    AuthLDAPURL ldap://other.ldap.host/o=dev?cn
</AuthnProviderAlias>

Alias "/secure" "/webpages/secure"
<Directory "/webpages/secure">
    AuthBasicProvider ldap-other-alias  ldap-alias1
    
    AuthType Basic
    AuthName "LDAP Protected Place"
    Require valid-user
    # Note that Require ldap-* would not work here, since the 
    # AuthnProviderAlias does not provide the config to authorization providers
    # that are implemented in the same module as the authentication provider.
</Directory>

AuthName Directive

Description:	Authorization realm for use in HTTP authentication
Syntax:	AuthName auth-domain
Context:	directory, .htaccess
Override:	AuthConfig
Status:	Base
Module:	mod_authn_core

This directive sets the name of the authorization realm for a directory. This realm is given to the client so that the user knows which username and password to send. AuthName takes a single argument; if the realm name contains spaces, it must be enclosed in quotation marks. It must be accompanied by AuthType and Require directives, and directives such as AuthUserFile and AuthGroupFile to work.

For example:

AuthName "Top Secret"

The string provided for the AuthName is what will appear in the password dialog provided by most browsers.

<AuthnProviderAlias> Directive

Description:	Enclose a group of directives that represent an extension of a base authentication provider and referenced by the specified alias
Syntax:	<AuthnProviderAlias baseProvider Alias> ... </AuthnProviderAlias>
Context:	server config
Status:	Base
Module:	mod_authn_core

<AuthnProviderAlias> and </AuthnProviderAlias> are used to enclose a group of authentication directives that can be referenced by the alias name using one of the directives AuthBasicProvider or AuthDigestProvider.

This directive has no affect on authorization, even for modules that provide both authentication and authorization.

AuthType Directive

Description:	Type of user authentication
Syntax:	AuthType None\|Basic\|Digest\|Form
Context:	directory, .htaccess
Override:	AuthConfig
Status:	Base
Module:	mod_authn_core

This directive selects the type of user authentication for a directory. The authentication types available are None, Basic (implemented by mod_auth_basic), Digest (implemented by mod_auth_digest), and Form (implemented by mod_auth_form).

To implement authentication, you must also use the AuthName and Require directives. In addition, the server must have an authentication-provider module such as mod_authn_file and an authorization module such as mod_authz_user.

The authentication type None disables authentication. When authentication is enabled, it is normally inherited by each subsequent configuration section, unless a different authentication type is specified. If no authentication is desired for a subsection of an authenticated section, the authentication type None may be used; in the following example, clients may access the /www/docs/public directory without authenticating:

<Directory "/www/docs">
    AuthType Basic
    AuthName Documents
    AuthBasicProvider file
    AuthUserFile "/usr/local/apache/passwd/passwords"
    Require valid-user
</Directory>

<Directory "/www/docs/public">
    AuthType None
    Require all granted
</Directory>

When disabling authentication, note that clients which have already authenticated against another portion of the server's document tree will typically continue to send authentication HTTP headers or cookies with each request, regardless of whether the server actually requires authentication for every resource.