Scaling Privileged Access for Modern Infrastructure: Real-World Insights
Apr 25
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Teleport

Database CA Migrations

In Teleport, self-hosted databases must be configured with certificates to enable mTLS authentication via the Teleport Database Service.

Teleport 10 introduced the db certificate authority (CA) to decouple CA rotation for self-hosted databases from the rest of the Teleport cluster.

Teleport 15 introduced the db_client CA to split the responsibilities of the Teleport db CA, which was acting as both host and client CA for Teleport self-hosted database access. The db_client CA was also added as a patch in Teleport 13.4.17 and 14.3.7.

The db and db_client CAs were both introduced as an automatic migration that occurs after upgrading Teleport.

Teleport's host/client database CA split is intended to limit the potential for lateral movement to other resources in the event that a database instance's private key is compromised.

This guide will provide information about why these CAs were added to Teleport and how to complete any pending migrations for your Teleport cluster.

Prerequisites

  • A running Teleport cluster. If you want to get started with Teleport, sign up for a free trial or set up a demo environment.

  • The tctl admin tool and tsh client tool version >= 15.2.2.

    On Teleport Enterprise, you must use the Enterprise version of tctl, which you can download from your Teleport account workspace. Otherwise, visit Installation for instructions on downloading tctl and tsh for Teleport Community Edition.

  • To check that you can connect to your Teleport cluster, sign in with tsh login, then verify that you can run tctl commands using your current credentials. tctl is supported on macOS and Linux machines. For example:
    tsh login --proxy=teleport.example.com --user=[email protected]
    tctl status

    Cluster teleport.example.com

    Version 15.2.2

    CA pin sha256:abdc1245efgh5678abdc1245efgh5678abdc1245efgh5678abdc1245efgh5678

    If you can connect to the cluster and run the tctl status command, you can use your current credentials to run subsequent tctl commands from your workstation. If you host your own Teleport cluster, you can also run tctl commands on the computer that hosts the Teleport Auth Service for full permissions.
  • A Teleport cluster that was upgraded from a version that predates either the db or db_client CA. If your Teleport cluster was created in Teleport 15 or later, then this guide does not apply to your cluster, because your db and db_client CAs were not migrated.

Teleport db CA migration

Your Teleport cluster's db CA can be used to issue certificates to self-hosted databases. This is convenient, because the Teleport Database Service trusts certificates issued by the db CA by default, so there is no additional TLS configuration in Teleport required.

Alternatively, you can issue certificates to your self-hosted databases using an external CA - you just need to configure the Teleport Database Service to trust that CA when connecting to your database(s).

For a static database defined in your Teleport Database Service teleport.yaml configuration file, set tls.ca_cert_file to a file containing your CA's root certificate.

For a dynamic database, put your CA's root certificate in spec.tls.ca_cert.

For examples and more information, consult the Database Access Configuration Reference.

Prior to Teleport 10, the Teleport host CA was used to issue certificates to self-hosted databases (via tctl auth sign). The db CA was introduced to decouple self-hosted database CA rotation from the rest of your Teleport cluster. The idea is that you should be able to rotate the CA used for self-hosted databases without affecting other resources connected to your cluster. Likewise, when you rotate your cluster's host CA, you should not have to worry about affecting self-hosted databases.

To avoid breaking database access after upgrading to Teleport 10, Teleport clusters are automatically migrated to create the db CA as a copy of the host CA.

If your cluster was upgraded to Teleport 10 and you use Teleport to issue certificates to your self-hosted databases, then you should ensure that you have completed the db CA migration. Otherwise, if you later rotate just one CA for any reason, a copy of the old CA will still exist. While this does not necessarily lead to a vulnerability in your cluster, it is bad security practice to keep an old CA around after rotating it.

To complete the db CA migration:

  • we recommend rotating your host CA
  • we strongly recommend rotating your db CA

Teleport db_client CA migration

The Teleport Database Service needs to authenticate itself to self-hosted database(s) using a client certificate, which requires that you configure your database(s) to trust Teleport's db_client CA. Prior to the introduction of the db_client CA, self-hosted databases had to be configured to trust the Teleport db CA for client authentication.

With the old approach - trusting the db CA for client connections - if a database's private key is compromised, and a db certificate was issued for that key, then it could be used to gain access to other databases.

Not all self-hosted databases are vulnerable to lateral movement after a private key compromise. For example, MySQL and PostgreSQL both verify that a client's certificate subject matches the client's database user. Other databases only verify that a client's certificate is trusted, but do not match the certificate subject to the database username. For example, Cassandra, ScyllaDB, and Redis do not verify the client cert subject. All of these databases can be configured to require password authentication after a successful mTLS handshake. However, for defense in depth, these databases should only mTLS handshake with a client that presents a db_client CA-issued certificate.

If your Teleport cluster was upgraded to Teleport >=13.4.17, >=14.3.7, or >=15, then you should ensure that you have completed the db_client migration. To complete the db_client CA migration:

  • we recommend rotating your db CA
  • we strongly recommend rotating your db_client CA.
  • we strongly recommend reconfiguring your databases' certificates after you complete the db_client CA rotation.
reconfiguring certs after db_client CA rotation

If you use tctl auth sign to reconfigure a database's certificates during a db_client CA rotation, then the trusted certificate output will include both the old and the new CA certificates. To complete the migration, you should reconfigure those databases again after the rotation - that way they will only trust the new CA.

If you don't want to reconfigure each database both during and after the db_client CA rotation, and you do not mind temporarily losing connectivity to your databases via Teleport, then you can just complete the db_client CA rotation and reconfigure your databases afterward.

1/2. Check for Teleport CA migrations

If you upgraded an existing cluster to Teleport >=10 and you have not rotated both your host and db CAs at least once since upgrading, then you should complete the db CA migration.

If you upgraded an existing cluster to Teleport >=13.4.17, >=14.3.7, or >=15 and you have not rotated both your db and db_client CAs at least once since upgrading, then you should complete the db_client CA migration.

If you are unsure whether you need to complete the migration for either the db or db_client CAs, you can check for duplicated CAs. Use these commands to print the X.509 certificate serial number for your host, db, and db_client CAs (in that order):

tctl auth export --type=tls-host | openssl x509 -noout -serial
tctl auth export --type=db | openssl x509 -noout -serial
tctl auth export --type=db-client | openssl x509 -noout -serial

If the db CA serial number matches the host CA serial number, then you need to complete the db CA migration.

If the db_client CA serial number matches the db CA serial number, then you need to complete the db_client CA migration.

2/2. Rotate CAs

If you need to complete both the db and db_client migrations, then a single rotation of each of the host, db, and db_client CAs is enough: you do not need to rotate the db CA twice.

If you need to rotate the host CA, we recommend completing that rotation before starting either of the db or db_client CA rotations: do not rotate other CAs in parallel with a host CA rotation. For information about host CA rotation, refer to the CA Rotation Guide.

Database CA rotations are a little different, because they involve configuring external resources (self-hosted databases) with new certificates during the rotation. You can (and should) rotate the db and db_client CAs at the same time to avoid repeating the database certificate reconfiguration steps.

For details on rotating the db or db_client CA, refer to the Database CA Rotation Guide.

Further reading