How is ClickHouse Authentication implemented with LDAP and Kerberos?

Introduction

ClickHouse supports external authentication methods such as LDAP and Kerberos. Here’s an overview of how authentication can be implemented with these protocols.

Overview of LDAP and Kerberos

1. LDAP Authentication: To authenticate users with LDAP, ClickHouse needs to be configured to connect to an LDAP server. This includes configuring the LDAP server’s address, port, and credentials. Once the LDAP server is configured, ClickHouse can authenticate users by binding to the LDAP server with the provided credentials and searching for the user’s distinguished name (DN).
2. Kerberos Authentication: To authenticate users with Kerberos, ClickHouse needs to be configured to use the Kerberos service account and keytab. This includes configuring the Kerberos principal and keytab file path. ClickHouse also needs to be configured to connect to a KDC(Kerberos Key Distribution Center) server. Once the Kerberos service account is configured, ClickHouse can authenticate users by using the Kerberos service account to request a ticket-granting ticket (TGT) from the KDC, and then using the TGT to request a service ticket for the ClickHouse service.

It’s important to note that the configuration of the external authentication methods, such as LDAP and Kerberos, can be complex and need to be done by a system administrator familiar with these protocols. Also, testing and monitoring the authentication process regularly is essential to ensure that the authentication process is working as expected.

Step-by-step implementation of ClickHouse authentication with LDAP and Kerberos

Here’s a high-level, step-by-step guide for implementing authentication with LDAP and Kerberos in ClickHouse:

LDAP Authentication

1. Install and configure an LDAP server.
2. Configure ClickHouse to connect to the LDAP server by adding the following lines in the config file:

<ldap>
host = ldap.example.com
port = 389
user = cn=admin,dc=example,dc=com
password = secret
base = dc=example,dc=com
timeout = 3
use_tls = 0
<networks>
<ip>
host = 192.168.1.0/24
user = cn=admin,dc=example,dc=com
password = secret
</ip>
</networks>
</ldap>

3. Set the authentication method to ‘LDAP’ in the config file, for example:

<users>
<default>
profile = default
auth = LDAP
</default>
</users>

4. Restart the ClickHouse server to apply the changes
5. Test the authentication by logging in with a user from the LDAP server

Kerberos Authentication

1. Install and configure a Kerberos server.
2. Configure ClickHouse to connect to the Kerberos server by adding the following lines in the config file:

<kerberos>
principal = clickhouse/hostname@EXAMPLE.COM
keytab = /path/to/keytab
kdc = kdc.example.com
kdc_port = 88
timeout = 3
</kerberos>

3. Set the authentication method to ‘Kerberos’ in the config file, for example:

<users>
<default>
profile = default
auth = Kerberos
</default>
</users>

4. Restart the ClickHouse server to apply the changes
5. Test the authentication by logging in with a user from the Kerberos server

Conclusion

It’s important to note that the above configuration is just an example, and the specific configuration will depend on the details of your LDAP and Kerberos servers. Also, It is a good practice to consult with security experts and conduct a thorough security assessment before deploying ClickHouse with LDAP and Kerberos authentication in a production environment.

To learn more about authentication & access control in ClickHouse, read the following article:

• ClickHouse Security: Role-Based Access Control (RBAC) in ClickHouse