This documentation assumes that you already have access to an LDAP directory, such as OpenLDAP or Active Directory, and that Guacamole has already been installed using Glyptodon Enterprise. If you do not already an LDAP directory ready, please set up LDAP before proceeding. If you do not already have Guacamole installed, please see the  quickstart guide.

Installing LDAP support for Guacamole

Glyptodon Enterprise packages Guacamole’s LDAP support within the glyptodon-guacamole-auth-ldap package:

$ sudo yum install glyptodon-guacamole-auth-ldap

Unlike the MySQL and PostgreSQL authentication backends, Guacamole’s LDAP support does not require a schema to be applied unless you intend to store connection data within your LDAP directory. If LDAP will be used only to authenticate Guacamole users, no schema modifications need be made, and a database should be used to store connection data.

If you do intend to store connection data within your LDAP directory, you will need to apply the provided schema modifications which create the guacConfigGroup object class. Be sure to first finish configuring Guacamole for LDAP authentication, and verify that Guacamole can successfully authenticate users against your LDAP directory.

Connecting Guacamole to LDAP

Guacamole’s main configuration file, /etc/guacamole/guacamole.properties, must be modified to point the LDAP directory:

$ sudo vi /etc/guacamole/guacamole.properties

The guacamole.properties file provided with Glyptodon Enterprise is organized into sections documented with blocks of comments and example properties. The first section which must be modified is marked “LDAP-1” and defines the TCP connection information for the LDAP directory. Uncomment the ldap-hostname property, modifying its value to point to your LDAP server:

##
## [LDAP-1] LDAP TCP connection information
##
## The TCP connection details of the LDAP server, as well as whether encryption
## should be used.
##
## Legal encryption methods are "none", for unencrypted connections, "ssl" 
## for LDAP over SSL/TLS (also known as LDAPS), or "starttls" for STARTTLS.
##

#ldap-hostname:          localhost
#ldap-port:              389
#ldap-encryption-method: none

By default, Guacamole will connect to your LDAP server without encryption. If your LDAP server uses encryption, you will need to uncomment and set the ldap-encryption-method property to “ssl” for LDAPS (LDAP over SSL/TLS) or “starttls” for STARTTLS.

The default port varies by encryption method, and will be 389 for unencrypted LDAP and STARTTLS, or 636 for LDAPS. If your LDAP server listens on a non-standard port, you will also need to uncomment and modify the ldap-port property.

Mapping Guacamole usernames to LDAP DN’s

To authenticate users using LDAP, Guacamole must translate usernames into their corresponding LDAP DN’s. Depending on the complexity of your LDAP directory, this can be as simple as adding a single attribute to a common base DN, or can involve an LDAP query.

The “LDAP-2” section defines the basic parameters required for either case:

##
## [LDAP-2] LDAP user / user DN description
##
## The base DN of all Guacamole users within the LDAP directory, and the
## attribute which contains each user's username. If the username attribute
## is not part of the DN, a seach DN will need to be provided, as well.
##

#ldap-user-base-dn:       ou=people,dc=example,dc=net
#ldap-username-attribute: uid

The base DN defined by the ldap-user-base-dn property should be the common base shared by all Guacamole users within your LDAP directory, while the attribute which contains the user’s username is defined by ldap-username-attribute. The base DN is always required if LDAP is being used.

Direct username mapping

By default, Guacamole will attempt to derive the user’s DN directly by prepending the username attribute to the base DN. For example, assume a user is attempting to login with the username “someUser”. If the base DN is “ou=people,dc=example,dc=net” and the username attribute is “uid” (the default), then Guacamole will perform the following steps to authenticate the user:

  1. Prepend the username to the base DN using the “uid” attribute, producing the DN: “uid=someUser,ou=people,dc=example,dc=net”.
  2. Attempt to bind using the DN “uid=someUser,ou=people,dc=example,dc=net” and the password provided by the user.
  3. If the bind attempt succeeds, authentication is successful.

Indirect username mapping

For more complex cases, where the user DN is cannot be directly derived by prepending the username attribute, Guacamole can instead issue an LDAP query to determine the user DN. This requires a search DN and password, defined with the ldap-search-bind-dn and ldap-search-bind-password properties respectively, which Guacamole will bind as when performing the query:

##
## [LDAP-3] LDAP user search DN
##
## The DN and password of the user to bind as when searching for the DN of each
## user attempting to log in. If omitted, the DN of each user will be derived
## directly using the user base DN and username attribute.
##

#ldap-search-bind-dn:       cn=someUser,ou=people,dc=example,dc=net
#ldap-search-bind-password: some_password

With the search DN and password configured, Guacamole will perform the following steps to authenticate a user:

  1. Bind to the LDAP directory using the search DN and password.
  2. Issue an LDAP query for objects within the subtree of the base DN that contain the user’s username within the defined username attribute.
  3. If exactly one such object is found, attempt to bind using the DN of that object and the password provided by the user.
  4. If the bind attempt succeeds, authentication is successful.

Completing installation

Guacamole will generally only load new extensions and reread guacamole.properties during the startup process. To apply the configuration changes, Guacamole (and thus Tomcat) must be restarted:

$ sudo systemctl restart tomcat