Forwarding events with Fluentd

In this guide, we will explain how to:

• Set up Teleport's event handler.
• Forward events with Fluentd.

Prerequisites

• Fluentd version v1.12.4.
• Docker version v20.10.7.

tsh login --proxy=teleport.example.com [email protected]
tctl status
Cluster  teleport.example.com
Version  9.3.7
CA pin   sha256:abdc1245efgh5678abdc1245efgh5678abdc1245efgh5678abdc1245efgh5678

tsh login --proxy=myinstance.teleport.sh [email protected]
tctl status
Cluster  myinstance.teleport.sh
Version  9.3.8
CA pin   sha256:sha-hash-here

Create a folder called fluentd to hold configuration and plugin state:

mkdir -p event-handler
cd event-handler

Step 1/6. Install the event handler plugin

The Teleport event handler runs alongside the Fluentd forwarder, receives events from Teleport's events API, and forwards them to Fluentd.

curl -L -O https://get.gravitational.com/teleport-event-handler-v9.3.7-linux-amd64-bin.tar.gz
tar -zxvf teleport-event-handler-v9.3.7-linux-amd64-bin.tar.gz

curl -L -O https://get.gravitational.com/teleport-event-handler-v9.3.7-darwin-amd64-bin.tar.gz
tar -zxvf teleport-event-handler-v9.3.7-linux-amd64-bin.tar.gz

docker pull quay.io/gravitational/teleport-plugin-event-handler:9.3.7

Step 2/6. Generate configuration

./teleport-event-handler configure . teleport.example.com:443

./teleport-event-handler configure . mytenant.teleport.sh

You'll see the following output:

Teleport event handler 0.0.1 07617b0ad0829db043fe779faf1669defdc8d84e

[1] mTLS Fluentd certificates generated and saved to ca.crt, ca.key, server.crt, server.key, client.crt, client.key
[2] Generated sample teleport-event-handler role and user file teleport-event-handler-role.yaml
[3] Generated sample fluentd configuration file fluent.conf
[4] Generated plugin configuration file teleport-event-handler.toml

Follow-along with our getting started guide:

https://goteleport.com/setup/guides/fluentd

The plugin generates several setup files:

ls -l
-rw------- 1 bob bob     1038 Jul  1 11:14 ca.crt
-rw------- 1 bob bob     1679 Jul  1 11:14 ca.key
-rw------- 1 bob bob     1042 Jul  1 11:14 client.crt
-rw------- 1 bob bob     1679 Jul  1 11:14 client.key
-rw------- 1 bob bob      541 Jul  1 11:14 fluent.conf
-rw------- 1 bob bob     1078 Jul  1 11:14 server.crt
-rw------- 1 bob bob     1766 Jul  1 11:14 server.key
-rw------- 1 bob bob      260 Jul  1 11:14 teleport-event-handler-role.yaml
-rw------- 1 bob bob      343 Jul  1 11:14 teleport-event-handler.toml

Step 3/6. Create a user and role for reading audit events

The configure command generates a file called teleport-event-handler-role.yaml that defines a teleport-event-handler role and a user with read-only access to the event API:

kind: user
metadata:
  name: teleport-event-handler
spec:
  roles: ['teleport-event-handler']
version: v2
---
kind: role
metadata:
  name: teleport-event-handler
spec:
  allow:
    rules:
      - resources: ['event']
        verbs: ['list','read']
version: v5

Use tctl to create the role and the user:

tctl create -f teleport-event-handler-role.yaml
user "teleport-event-handler" has been created
role 'teleport-event-handler' has been created

Step 4/6. Create teleport-event-handler credentials

Enable impersonation of the Fluentd plugin user

In order for the Fluentd plugin to forward events from your Teleport cluster, it needs a signed identity file from the cluster's certificate authority. The Fluentd user cannot request this itself, and requires another user to impersonate this account in order to request a certificate.

Create a role that enables your user to impersonate the Fluentd user. First, paste the following YAML document into a file called teleport-event-handler-impersonator.yaml:

kind: role
version: v5
metadata:
  name: teleport-event-handler-impersonator
spec:
  # SSH options used for user sessions
  options:
    # max_session_ttl defines the TTL (time to live) of SSH certificates
    # issued to the users with this role.
    max_session_ttl: 10h

  # allow section declares a list of resource/verb combinations that are
  # allowed for the users of this role. by default nothing is allowed.
  allow:
    impersonate:
      users: ["teleport-event-handler"]
      roles: ["teleport-event-handler"]

Next, create the role:

tctl create teleport-event-handler-impersonator.yaml

Assign this role to the current user by running the following command, substituting the user as appropriate:

tctl get users/<USER> > out.yaml

Now edit out.yaml, adding teleport-event-handler-impersonator to the list of existing roles and update via tctl again:

$ tctl create -f out.yaml

Log in to your Teleport cluster again to assume the new role.

Export an identity file for the Fluentd plugin user

The Fluentd Teleport plugin uses the teleport-event-handler role and user to read events. We export an identity file for the user with the tctl auth sign command.

tctl auth sign --format=tls --user=teleport-event-handler --out=auth

tctl auth sign --user=teleport-event-handler --out=identity

Step 5/6. Start the Fluentd forwarder

The Fluentd plugin will send events to your Fluentd instance using keys generated on the previous step.

The fluent.conf file generated earlier configures your Fluentd instance to accept events using TLS and print them:

<source>
    @type http
    port 8888

    <transport tls>
        client_cert_auth true

        # We are going to run fluentd in Docker. /keys will be mounted from the host file system.
        ca_path /keys/ca.crt
        cert_path /keys/server.crt
        private_key_path /keys/server.key
        private_key_passphrase ********** # Passphrase generated along with the keys
    </transport>

    <parse>
      @type json
      json_parser oj

      # This time format is used by the plugin. This field is required.
      time_type string
      time_format %Y-%m-%dT%H:%M:%S
    </parse>
</source>

# Events sent to test.log will be dumped to STDOUT.
<match test.log> 
  @type stdout
</match>

To try out this Fluentd configuration, start your fluentd instance:

docker run -u $(id -u ${USER}):$(id -g ${USER}) -p 8888:8888 -v $(pwd):/keys -v $(pwd)/fluent.conf:/fluentd/etc/fluent.conf fluent/fluentd:edge

Step 6/6. Start the event handler plugin

Earlier, we generated a file called teleport-event-handler.toml to configure the Fluentd event handler. This file includes setting similar to the following:

storage = "./storage"
timeout = "10s"
batch = 20
namespace = "default"

[forward.fluentd]
ca = "/home/sasha/scripts/event-handler/ca.crt"
cert = "/home/sasha/scripts/event-handler/client.crt"
key = "/home/sasha/scripts/event-handler/client.key"
url = "https://localhost:8888/test.log"

[teleport]
addr = "example.teleport.com:443"
identity = "identity"

storage = "./storage"
timeout = "10s"
batch = 20
namespace = "default"

[forward.fluentd]
ca = "/home/sasha/scripts/event-handler/ca.crt"
cert = "/home/sasha/scripts/event-handler/client.crt"
key = "/home/sasha/scripts/event-handler/client.key"
url = "https://localhost:8888/test.log"

[teleport]
addr = "example.teleport.com:443"
client_key = "auth.key"
client_crt = "auth.crt"
root_cas = "auth.cas"

To start the event handler, run the following command:

./teleport-event-handler start --config teleport-event-handler.toml

./teleport-event-handler start --config teleport-event-handler.toml --start-time "2021-05-05T00:00:00Z"

Once the handler starts, you will see notifications about scanned and forwarded events:

INFO[0046] Event sent id=0b5f2a3e-faa5-4d77-ab6e-362bca0994fc ts="2021-06-08 11:00:56.034 +0000 UTC" type=user.login
...

Next Steps

• Read more about impersonation here.