Cert Authority Rotation

Prerequisites

tsh login --proxy=teleport.example.com [email protected]
tctl status
Cluster  teleport.example.com
Version  12.1.1
CA pin   sha256:abdc1245efgh5678abdc1245efgh5678abdc1245efgh5678abdc1245efgh5678

tsh login --proxy=myinstance.teleport.sh [email protected]
tctl status
Cluster  myinstance.teleport.sh
Version  12.1.1
CA pin   sha256:sha-hash-here

Certificate Authority rotation

This section will show you how to implement certificate rotation in practice.

If you are using CA Pinning when adding new nodes, the CA pin will change after the rotation. Make sure you use the new CA pin when adding nodes after rotation.

Rotation phases

The rotation consists of several phases:

• standby: All operations have completed or haven't started yet.
• init: All components are notified of the rotation. A new certificate authority is issued, but not used. It is necessary for remote trusted clusters to fetch the new certificate authority, otherwise new clients will reject it.
• update_clients: Internal clients certs are updated and reloaded. Servers will use and respond with old credentials because clients have no idea about new certificates at first.
• update_servers: Servers reload and start serving TLS and SSH certificates signed by the new certificate authority, but will still accept certificates issued by the old certificate authority.
• rollback: The rotation was aborted and is rolling back to the old certificate authority.

Rotation types

There are two kinds of certificate rotations:

• Manual: it is the cluster administrator's responsibility to transition between each phase of the rotation while monitoring the state of the cluster. Manual rotations provide the greatest level of control, and are performed by providing the desired phase using the --phase flag with the tctl auth rotate command.
• Semi-automatic: Teleport automatically transitions between phases of the rotation after some amount of time (known as a grace period) elapses.

For both types of rotations, the cluster goes through the phases in the following order:

• standby -> init -> update_clients -> update_servers -> standby

Administrators can abort the rotation and revert all changes any time before the rotation is completed by entering the rollback phase.

tctl auth rotate --phase=rollback --type=type --manual

For example, if an admin has detected that some nodes failed to upgrade during update_servers, they can roll back to the previous certificate authority, and the phase transitions look like this:

• update_servers -> rollback -> standby.

To specify which certificate authority to rotate, you must provide a value via the --type flag. If no value is provided, tctl will display an error and exit. To replicate the functionality of versions prior to 12, where all certificate authorities were rotated by default, you can pass in --type=all. Keep in mind that this functionality is deprecated and will be removed in a future version.

Manual rotation

In manual mode, we manually transition between phases while monitoring the state of the cluster.

Start the rotation

Initiate the manual rotation of host certificate authorities:

tctl auth rotate --phase=init --type=type --manual
Updated rotation phase to "init". To check status use 'tctl status'

Use tctl to confirm that there is an active rotation in progress:

tctl status
Cluster  acme.cluster
Version  12.1.1
Host CA  initialized (mode: manual, started: Sep 20 01:44:36 UTC, ending: Sep 21 07:44:36 UTC)
User CA  rotated Sep 20 01:42:54 UTC
Jwt CA   rotated Sep 20 01:42:54 UTC
CA pin   sha256:hash

Check the status of connected nodes:

Check rotation status of the nodes
tctl get nodes --format=json | jq '.[] | {hostname: .spec.hostname, rotation: .spec.rotation.state, phase: .spec.rotation.phase}'
{
  "hostname": "terminal",
  "rotation": "in_progress",
  "phase": "init"
}

In this example, the node named terminal has updated its status to phase init. This means it has downloaded a new CA public key and is ready for state transitions.

Update clients

Execute the transition from init to update_clients:

tctl auth rotate --phase=update_clients --type=type --manual
Updated rotation phase to "update_clients". To check status use 'tctl status'
tctl status
Cluster  acme.cluster
Version  12.1.1
Host CA  rotating clients (mode: manual, started: Sep 20 01:44:36 UTC, ending: Sep 21 07:44:36 UTC)

Verify that nodes have caught up and now see the current cluster state:

tctl get nodes --format=json | jq '.[] | {hostname: .spec.hostname, rotation: .spec.rotation.state, phase: .spec.rotation.phase}'
{
  "hostname": "terminal",
  "rotation": "in_progress",
  "phase": "update_clients"
}

Update servers

Now that all nodes have caught up, execute the transition from update_clients to update_servers:

tctl auth rotate --phase=update_servers --type=type --manual
Updated rotation phase to "update_servers". To check status use 'tctl status'
tctl status
Cluster  acme.cluster
Version  12.1.1
Host CA  rotating servers (mode: manual, started: Sep 20 01:44:36 UTC, ending: Sep 21 07:44:36 UTC)

Verify that nodes have caught up:

tctl get nodes --format=json | jq '.[] | {hostname: .spec.hostname, rotation: .spec.rotation.state, phase: .spec.rotation.phase}'
{
  "hostname": "terminal",
  "rotation": "in_progress",
  "phase": "update_servers"
}

Finish the rotation

Before wrapping up, verify that you have not lost any nodes and can connect to them, for example:

tsh ssh [email protected]

tctl auth rotate --phase=standby --type=type --manual

Verify that the rotation has completed with tctl:

tctl status
Cluster  acme.cluster
Version  12.1.1
Host CA  rotated Sep 20 02:11:25 UTC
User CA  rotated Sep 20 01:42:54 UTC
Jwt CA   rotated Sep 20 01:42:54 UTC
CA pin   sha256:hash

Nodes should catch up and be on standby:

tctl get nodes --format=json | jq '.[] | {hostname: .spec.hostname, rotation: .spec.rotation.state, phase: .spec.rotation.phase}'
{
  "hostname": "terminal",
  "rotation": "standby",
  "phase": "standby"
}

Semi-Automatic rotation

You can trigger semi-automatic rotation by omitting the --manual and --phase flags.

tctl auth rotate --type=host

This will trigger a rotation process for hosts with a default grace period of 48 hours. During the grace period, certificates issued both by old and new certificate authority work.

You can customize grace period and CA type with additional flags:

Rotate only user certificates with a grace period of 200 hours:
tctl auth rotate --type=user --grace-period=200h
Rotate only host certificates with a grace period of 8 hours:
tctl auth rotate --type=host --grace-period=8h

The rotation takes time, especially for hosts, because each node in a cluster needs to be notified that a rotation is taking place and request a new certificate for itself before the grace period ends.

During semi-automatic rotations, Teleport will attempt to divide the grace period so that it spends an equal amount of time in each phase before transitioning to the next phase. This means that using a shorter grace period will result in faster state transitions.

The grace period needs to be long enough for all nodes in a cluster to request a new certificate. If some nodes go offline during the rotation and come back only after the grace period has ended, they will be forced to leave the cluster, i.e. users will no longer be allowed to SSH into them.

Check the cluster status:

tctl status
Cluster  acme.cluster
Version  12.1.1
Host CA  initialized (mode: manual, started: Sep 20 01:44:36 UTC, ending: Sep 21 07:44:36 UTC)

Check the status of individual nodes:

Check rotation status of the nodes
tctl get nodes --format=json | jq '.[] | {hostname: .spec.hostname, rotation: .spec.rotation.state, phase: .spec.rotation.phase}'
{
  "hostname": "terminal",
  "rotation": "in_progress",
  "phase": "init"
}

The node named terminal has updated its status to phase init. This means it has downloaded a new CA public key and is ready for state transitions.

Rollback

Rollback must be performed before the rotation enters standby state.

First, enter the rollback phase with a manual phase transition:

tctl auth rotate --phase=rollback --type=type --manual
Updated rotation phase to "rollback". To check status use 'tctl status'

Make sure that any nodes which have already updated have caught up and entered the rollback phase.

Check rotation status of the nodes
tctl get nodes --format=json | jq '.[] | {hostname: .spec.hostname, rotation: .spec.rotation.state, phase: .spec.rotation.phase}'
{
  "hostname": "terminal",
  "rotation": "in_progress",
  "phase": "rollback"
}

If connectivity to any of the nodes was lost during the rotation, this is likely because they were still using the old cert authority. Connectivity to these nodes should be restored when the rollback completes and the old certificate authority is made active.

Further reading

How the Teleport Certificate Authority works.