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LDAP Auth

Instructions for authenticating users with LDAP

Keeper Connection Manager provides support for LDAP authentication.

Docker Environmental Variables

The image keeper/guacamole can be modified to support LDAP using environmental variables. See the LDAP_* variables defined in the documentation.

Auto Docker and Docker Compose Install Method

If you installed Keeper Connection Manager using the Docker Install method, this does not come preconfigured with LDAP support. The instructions for activating LDAP are below:

(1) On the local instance, stop the containers.

Auto Docker Install:

sudo ./kcm-setup.run stop

Docker Compose Install:

cd /path/to/docker-compose.yml
docker-compose stop

(2) Edit the docker-compose file

Using the simple or custom docker method requires modification of docker-compose.yml file to add LDAP support. As root, edit your docker-compose.yml file and find the "guacamole" section.

    guacamole:
        image: keeper/guacamole:2
        environment:
            ACCEPT_EULA: "Y"
            GUACD_HOSTNAME: "guacd"
            MYSQL_HOSTNAME: "db"
            MYSQL_DATABASE: "guacamole_db"
            MYSQL_USERNAME: "guacamole_user"
            MYSQL_PASSWORD: "xxxxxxx"
            
            # LDAP Connection
            LDAP_HOSTNAME: "localhost"
            LDAP_PORT: 389
            LDAP_ENCRYPTION_METHOD: "none"
            
            # Mapping Guacamole usernames to LDAP DN’s
            LDAP_USER_BASE_DN: "ou=people,dc=example,dc=net"
            
            ## Optional Settings ##
            LDAP_USERNAME_ATTRIBUTE: "sAMAccountName"
            
            # Indirect Username Mapping
            LDAP_SEARCH_BIND_DN: "cn=someUser,ou=people,dc=example,dc=net"
            LDAP_SEARCH_BIND_PASSWORD: "some_password"
            
            # Mapping Guacamole groups to LDAP DN's
            LDAP_GROUP_BASE_DN: "ou=groups,dc=example,dc=net"
            LDAP_GROUP_NAME_ATTRIBUTE: "cn"

Optional settings

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.

Add the following options to docker-compose.yml to enable username mapping

            # Mapping Guacamole usernames to LDAP DN’s
            LDAP_USER_BASE_DN: "ou=people,dc=example,dc=net"
            LDAP_USERNAME_ATTRIBUTE: "sAMAccountName"

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:

            # Indirect Username Mapping
            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.

Mapping Guacamole groups to LDAP DN’s

Access to connections within Guacamole may be dictated through LDAP user groups via either of two mechanisms:

  1. Defining connections directly within LDAP using schema modifications and dictating group access using the "seeAlso" attribute.

  2. Mapping LDAP groups to Guacamole groups and leveraging a database to dictate access.

As it is usually preferable to avoid modifying the LDAP schema, mapping LDAP groups to Guacamole groups is recommended. Doing this will require defining the base DN under which all relevant LDAP groups may be found and defining the LDAP attribute that should be used by Guacamole to determine the unique name of the group:

            # Mapping Guacamole groups to LDAP DN's
            LDAP_GROUP_BASE_DN: "ou=groups,dc=example,dc=net"
            LDAP_GROUP_NAME_ATTRIBUTE: "cn"

If connections are being stored within LDAP using "guacConfigGroup" objects, and you wish to control access to these connections via LDAP groups, this is accomplished using the standard "seeAlso" attribute and the LDAP_GROUP_BASE_DN property is required.

If connections are being stored outside of LDAP, such as within a database, and you wish to control access using LDAP groups, both LDAP_GROUP_BASE_DN and LDAP_GROUP_NAME_ATTRIBUTE will be required. The group membership of a user cannot be queried without a base DN, and the unique name to be used by other parts of Guacamole to represent the group cannot be determined without the name attribute.

(3) Restart the containers

Simple Install:

sudo ./kcm-setup.run upgrade

The containers should restart after the upgrade. If not run:

sudo ./kcm-setup.run start

Custom Install:

sudo su
docker-compose up -d

Configuration is complete.

Custom Root Certificate

If you require the use of a custom Root Certificate for your LDAP server, you can volume mount the file /etc/pki/ca-trust/extracted/java/cacerts in your Docker Compose to override this certificate in the guacamole docker container.

  • Import the certificate into a Java truststore using "keytool".

  • Volume mount the cacerts file to your target guacamole docker container

Using Multiple LDAP Servers

Multiple LDAP Servers with KCM

Auto Docker or Docker Compose

When using the docker version of KCM, you can list the multiple LDAP servers in your docker-compose.yml file using the environment variable LDAP_SERVERS in the environment section of the guacamole service, as shown below:

version: "3"
services:
    guacamole:
        image: keeper/guacamole:2
        restart: unless-stopped
        depends_on:
            - guacd
            - db
        environment:
            ACCEPT_EULA: "Y"
            GUACD_HOSTNAME: "guacd"
            LDAP_SERVERS: |
              - hostname: server1.example.net
                user-base-dn: OU=Users,DC=example,DC=net
                username-attribute: sAMAccountName
                search-bind-dn: CN=Guacamole,OU=Services,DC=example,DC=net
                search-bind-password: SomePassword!

              - hostname: server2.example.net
                user-base-dn: OU=Users,DC=example,DC=net
                username-attribute: sAMAccountName
                search-bind-dn: CN=Guacamole,OU=Services,DC=example,DC=net
                search-bind-password: SomePassword!

Using LDAP_SERVERS will automatically create /etc/guacamole/ldap-servers.yml within the guacamole container.

When using LDAP_SERVERS in your docker-compose.yml, don't volume mount the ldap-servers.yml file (since this will be handled automatically). For advanced or non-docker installations, follow this guide.

Storing connection data within LDAP

Defining the guacConfigGroup object class

When connection data is stored within your LDAP directory, each connection is represented by a special type of LDAP group, and permissions related to Guacamole connections can be managed directly with LDAP based on user membership of these groups. Doing this requires schema modifications which add a new object class called guacConfigGroup.

An LDIF file defining the schema changes in a manner compatible with OpenLDAP is provided by the kcm-guacamole-auth-ldap package within /opt/keeper/share/guacamole-auth-ldap/schema/guacConfigGroup.ldif. This file can be applied to your OpenLDAP server using the “ldapadd” command:

$ sudo ldapadd -Q -Y EXTERNAL -H ldapi:/// -f /opt/keeper/share/guacamole-auth-ldap/schema/guacConfigGroup.ldif

Once this is done, connections can be defined by creating new guacConfigGroup objects within the LDAP directory. Each guacConfigGroup accepts a single guacConfigProtocol attribute, defining the protocol associated with the connection, and any number of guacConfigParameter attributes, each defining a connection parameter name/value pair. Users that should have access to the connection must be added as members of the guacConfigGroup using the member attribute.

For example, a connection accessible to two users which uses VNC to connect to localhost at port 5900 with the password “secret” could be defined with the following LDIF file:

dn: cn=Example Connection,ou=groups,dc=example,dc=net
objectClass: guacConfigGroup
objectClass: groupOfNames
cn: Example Connection
guacConfigProtocol: vnc
guacConfigParameter: hostname=localhost
guacConfigParameter: port=5900
guacConfigParameter: password=secret
member: cn=user1,ou=people,dc=example,dc=net
member: cn=user2,ou=people,dc=example,dc=net

Configuring Guacamole to read connections from LDAP

Auto Docker And Docker Compose Install Methods:

To read connection data from LDAP, Guacamole’s main configuration file, modify the /etc/kcm-setup/docker-compose.yml file.

The base DN of all connections defined within LDAP must be specified using the LDAP_CONFIG_BASE_DN property. This base DN should be the DN of the portion of the LDAP directory whose subtree contains all Guacamole connections accessible via LDAP. Only connections defined within the subtree of this base DN will be visible.

The EXTENSION_PRIORITY property specifies the order that extensions should be loaded relative to each other. In the following example, all other extensions take priority over LDAP:

   guacamole:
        image: keeper/guacamole:2
        environment:
            ACCEPT_EULA: "Y"
            GUACD_HOSTNAME: "guacd"
            MYSQL_HOSTNAME: "db"
            MYSQL_DATABASE: "guacamole_db"
            MYSQL_USERNAME: "guacamole_user"
            MYSQL_PASSWORD: "xxxxxxx"
            
            # LDAP Connection
            LDAP_HOSTNAME: "localhost"
            LDAP_PORT: 389
            LDAP_ENCRYPTION_METHOD: "none"
            
            ## Optional Settings ##
            # Read Connections from LDAP
            LDAP_CONFIG_BASE_DN: "ou=connections,dc=example,dc=net"
            # Force all other extensions to take priority over LDAP
            EXTENSION_PRIORITY: "*, ldap"

Controlling access using group membership

Auto Docker and Docker Compose Install Method

To control group membership using LDAP, modify the /etc/kcm-setup/docker-compose.yml file.

It is also possible grant entire groups access to connections using the seeAlso attribute. This attribute is a standard LDAP attribute, and will be taken into account by Guacamole if the LDAP_GROUP_BASE_DN property is defined. This property defines the root of the subtree containing all groups which may apply to Guacamole users authenticated using LDAP:

  guacamole:
        image: keeper/guacamole:2
        environment:
            ACCEPT_EULA: "Y"
            GUACD_HOSTNAME: "guacd"
            MYSQL_HOSTNAME: "db"
            MYSQL_DATABASE: "guacamole_db"
            MYSQL_USERNAME: "guacamole_user"
            MYSQL_PASSWORD: "xxxxxxx"
            
            # LDAP Connection
            LDAP_HOSTNAME: "localhost"
            LDAP_PORT: 389
            LDAP_ENCRYPTION_METHOD: "none"
            
            ## Optional Settings ##
            # Mapping Guacamole groups to LDAP DN's
            LDAP_GROUP_BASE_DN: "ou=groups,dc=example,dc=net"
            LDAP_GROUP_NAME_ATTRIBUTE: "cn"

Completing installation

Auto Docker Install Method

sudo ./kcm-setup.run stop
sudo ./kcm-setup.run upgrade

Docker Compose Install Method

docker-compose stop
docker-compose up -d

Using LDAP with a database

If multiple authentication methods are installed, Guacamole will poll each method as it attempts to authenticate users, and will retrieve connection data from each method once a user has successfully authenticated. This behavior is designed to allow authentication methods to work together, and can be leveraged to authenticate Guacamole users against LDAP while storing the connection data for those users within MySQL, PostgreSQL, or SQL Server.

Guacamole's definition of identity

When reading data from multiple authentication methods, Guacamole compares the unique identifiers of users (usernames) and groups to determine identity. This means that user accounts from different authentication systems will be automatically combined by Guacamole upon successful authentication as long as those user accounts have the same username, and group memberships will take effect across authentication systems so long as the unique names of those groups match.

If both LDAP and a database authentication method have been configured, Guacamole will automatically attempt to authenticate against both systems whenever a user attempts to log in. The LDAP account will be considered equivalent to the database user if the username is identical, and that user will have access to any data associated with them via the database, as well as any visible objects within the LDAP directory. If that user has permission to query their group memberships within LDAP, and Guacamole has been configured to query groups within LDAP, then the user's group membership will also be retrieved upon authentication, and the user will have access to any data associated with those groups via the database.

For a user known to exist within LDAP, that user can be granted permissions to connections within the database by logging in as the administrative user (by default, “guacadmin”) and creating a corresponding database account having the same username. By leaving the password unspecified for the database account, the user will only be able to log in using LDAP, but will still have access to any associated connections defined within the database.

Administering LDAP users within Guacamole

Rather than having to manually look up users or groups within the LDAP directory, and then manually create those same users and groups within Guacamole, it is possible to set up administrative user accounts which can already see and manage available LDAP objects. This streamlines the administrative process, reducing the number of users which must be manually created to one.

To see LDAP objects within Guacamole’s administrative interface, one of the following tasks must be performed:

  1. An administrative user within the Guacamole database, such as the default “guacadmin” user, must be manually created within LDAP with the same username and with sufficient privileges to query all Guacamole users and groups defined within LDAP.

  2. An administrative user must be manually created within Guacamole having the same username as an LDAP user with sufficient privileges to query all Guacamole users and groups defined within LDAP.

Because a Guacamole user created as defined above would have access to LDAP users and groups, database users and groups, and database connections, all of this data will be unified within the same administrative interface within Guacamole. The user will be able to grant LDAP users and groups access to connections within the database to just as they would if only the database were in use.