Chapter 6. Set up LDAP Authentication

The default LDAP authentication type is configured by adding the following authentication provider to the cluster's topology file. When enabled, the Knox Gateway authenticates users against the configured LDAP store by binding to the User Distinguished Name (UserDN) that is defined by the pattern specified in the UserDnTemplate. Use this provider to authenticate users who have to the same UserDN pattern.

To authenticate users that are in different branches of the LDAP Directory Information Tree (DIT), who have a login token that is not part of the UserDN, or to lookup group membership, see Advanced LDAP Configuration.

	Note
	The Apache Shiro `JndiLdapRealm` provides HTTP BASIC authentication against an LDAP user directory. This provider currently supports a single Organizational Unit (OU) only and does not support nested OUs. An identity assertion provider is required when authentication is configured, see Configuring Service Users and Groups.

To enable LDAP authentication:

Open the cluster topology descriptor file, $cluster-name.xml, in a text editor.
Add the ShiroProvider authentication provider to /topology/gateway as follows:
```
<provider>
   <role>authentication</role>
   <name>ShiroProvider</name>
   <enabled>true</enabled>
   <param>
        <name>main.ldapRealm</name>
        <value>org.apache.shiro.realm.ldap.JndiLdapRealm</value>
   </param>
        <name>main.ldapRealm.userDnTemplate</name>
        <value>$USER_DN</value>
   </param>
        <name>main.ldapRealm.contextFactory.url</name>
        <value>$protocol://$ldaphost:$port</value>
   </param>
        <name>main.ldapRealm.contextFactory.authenticationMechanism</name>
        <value>simple</value>
   </param>
        <name>urls./**</name>
        <value>$auth_type</value>
   </param>
        <name>sessionTimeout</name>
        <value>$minutes</value>
   </param>
 </provider>
```
where the following variables are specific to your environment:
- $USER_DN is a comma separated list of attribute and value pairs that define the User Distinguished Name (DN). The first pair must be set to "$attribute_name={0}" indicating that the $attribute_name is equal to the user token parsed from the request.
  For example, the first attribute in an OpenLdap definition is UID={0}. The main.ldapRealm.userDnTemplate parameter is only required when authenticating against an LDAP store that requires a full User DN.
- $protocol://$ldaphost:$port is the URL of the LDAP service, Knox Gateway supports LDAP or LDAPS protocols. When using SSL specify the protocol as ldaps and if using a self-signed certificate, ensure that the client verification certificate is installed on the Knox server.
- $auth_type is either authcBasic which provides basic authentication for both secured and non-secured requests or ssl, authcBasic which rejects non-secured requests and provides basic authentication of secured requests.
- $minutes is the session idle time in minutes, the default timeout is 30 minutes.
Save the file.
The gateway creates a new WAR file with modified timestamp in /var/lib/knox/data/deployments .

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