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LDAP Authentication Advanced

By Kong Inc.

Add LDAP Bind Authentication with username and password protection. The plugin checks for valid credentials in the Proxy-Authorization and Authorization headers (in that order).

The LDAP Authentication Advanced plugin provides features not available in the open-source LDAP Authentication plugin, such as LDAP searches for group and consumer mapping:

  • Ability to authenticate based on username or custom ID.
  • The ability to bind to an enterprise LDAP directory with a password.
  • The ability to obtain LDAP groups and set them in a header to the request before proxying to the upstream. This is useful for Kong Manager role mapping.

Usage

To authenticate a user, the client must set credentials in either the Proxy-Authorization or Authorization header in the following format:

credentials := [ldap | LDAP] base64(username:password)

The Authorization header would look something like:

Authorization:  ldap dGxibGVzc2luZzpLMG5nU3RyMG5n

The plugin validates the user against the LDAP server and caches the credentials for future requests for the duration specified in config.cache_ttl.

You can set the header type ldap to any string (such as basic) using config.header_type.

Upstream Headers

When a client has been authenticated, the plugin appends some headers to the request before proxying it to the upstream service, so that you can identify the consumer in your code:

  • X-Consumer-ID: The ID of the consumer in Kong.
  • X-Consumer-Custom-ID: The custom_id of the consumer (if set).
  • X-Consumer-Username: The username of the consumer (if set).
  • X-Credential-Identifier: The identifier of the credential (only if the consumer is not the anonymous consumer).
  • X-Anonymous-Consumer: Is set to true if authentication fails, and the anonymous consumer is set instead.

You can use this information on your side to implement additional logic. You can use the X-Consumer-ID value to query the Kong Admin API and retrieve more information about the consumer.

LDAP Search and config.bind_dn

LDAP directory searching is performed during the request/plugin lifecycle. It is used to retrieve the fully qualified DN of the user so a bind request can be performed with a user’s given LDAP username and password. The search for the user being authenticated uses the config.bind_dn property. The search uses scope="sub", filter="<config.attribute>=<username>", and base_dn=<config.base_dn>. Here is an example of how it performs the search using the ldapsearch command line utility:

ldapsearch -x \
  -h "<config.ldap_host>" \
  -D "<config.bind_dn>" \
  -b "<config.attribute>=<username><config.base_dn>" \
  -w "<config.ldap_password>"

Using Service Directory Mapping on the CLI

When using only RBAC Token authorization, Service Directory Mapping to Kong Roles does not take effect. If you need to use CLI access with your Service Directory mapping, you can use the same authentication mechanism that Kong Manager uses to secure browser sessions.

Authenticate User Session

Retrieve a secure cookie session with the authorized LDAP user credentials:

$ curl -c /tmp/cookie http://localhost:8001/auth \
-H 'Kong-Admin-User: <LDAP_USERNAME>' \
--user <LDAP_USERNAME>:<LDAP_PASSWORD>

Now the cookie is stored at /tmp/cookie and can be read for future requests:

$ curl -c /tmp/cookie -b /tmp/cookie http://localhost:8001/consumers \
-H 'Kong-Admin-User: <LDAP_USERNAME>'

Because Kong Manager is a browser application, if any HTTP responses see the Set-Cookie header, then it will automatically attach it to future requests. This is why it is helpful to utilize cURL’s cookie engine or HTTPie sessions. If storing the session is not desired, then the Set-Cookie header value can be copied directly from the /auth response and used with subsequent requests.

Notes

Referrals are not supported in the plugin. A workaround is to hit the LDAP Global Catalog instead, which is usually listening on a different port than the default 389. That way, referrals don’t get sent back to the plugin.

The plugin obtains LDAP groups and sets them in a header, x-authenticated-groups, to the request before proxying to the upstream. This is useful for Kong Manager role mapping.