Infrastructure Layer


The Gremlin daemon (gremlind) connects to the Gremlin Control Plane and waits for attack orders from you. When it receives attack orders, it uses the Gremlin client (gremlin) to run the attack.

To connect the Gremlin daemon to the Control Plane, you need your client credentials, provided either via secret-based authentication using TEAM ID and SECRET, or via signature-based authentication using PEM certificates. These credentials are NOT the same as the email/password credentials you use to access the Gremlin Web App. To read about User authentication via the Gremlin Web App, see User Management and Authentication..

Client Authentication Methods

There are two methods for authenticating clients with Gremlin

  • secret authentication involves a secret string value that Gremlin clients use to prove their identity. Secrets are created from the Gremlin UI, and are like passwords. They can never be retrieved from Gremlin after creation (only reset)
  • signature authentication requires supplying a public and private RSA certificate-key pair to Gremlin clients. This certificate pair is created from the Gremlin UI, and can be redownloaded at any time, but they expire 1 year from the date of creation

Both authentication methods can be configured via configuration file or environment variables. Learn more about how to configure Gremlin from the configuration page.

Secret-based Authentication

Create a Secret

To use secret-based authentication as a new user, sign in to the Gremlin Web App. Go to Team Settings, and click your Team. From the team settings page, on the secret line, click Create to create a new secret.

NOTE: If a secret already exists, you must revoke the existing secret; this will cause a new one to be generated. If you revoke an existing secret and create a new one, you will need to reconfigure any existing clients.

Configure Clients with Secret

To configure Gremlin clients for secret authentication, follow one of the configuration methods:

  • set team_id and team_secret in your config.yaml
1team_id: 11111111-1111-1111-1111-111111111111
2team_secret: 11111111-1111-1111-1111-111111111111
  • or pass environment variables GREMLIN_TEAM_ID and GREMLIN_TEAM_SECRET directly to the gremlind process.
1# export these to the gremlind process or save them to /etc/default/gremlind (used by Systemd and SysV)
gremlin init

Additionally, secret authentication can also be set up via gremlin init

1gremlin init --tag service=my-api --tag service-version=1.0.0 --tag service-type=http

If secret-based auth is successful, the client will create a hidden file, .credentials in the gremlin userโ€™s home directory. This file contains an authentication token that gremlind uses to connect to the Gremlin Control Plane.

Signature-based Authentication

Download a Certificate Pair

To download your certificate, navigate to Company Settings on the Web UI.

Then click the Team whose client credentials you want to download. (Each team has its own client credentials.)

Company Settings

Each Team page has everything your Gremlin clients need to authenticate to the Control Plane: the Team ID and Certificate.

Click Download to get your Team Certificate.

Team page

The downloaded zip file contains both a public-key certificate and a matching private key. Unzip the file, and register Gremlin clients to the Control Plane with the included certificate, private key, and your Team ID.

Configure Clients with Certificate Pair

To configure Gremlin clients for signature authentication, follow one of the configuration methods:

  • set team_id, team_certificate, and team_private_key in your config.yaml
2team_id: 11111111-1111-1111-1111-111111111111
3team_certificate: file:///var/lib/gremlin/cert.pem
4team_private_key: file:///var/lib/gremlin/key.pem
  • or pass environment variables GREMLIN_TEAM_ID, GREMLIN_TEAM_CERTIFICATE_OR_FILE, and GREMLIN_TEAM_PRIVATE_KEY_OR_FILE directly to the gremlind process
1# export these to the gremlind process or save them to /etc/default/gremlind (used by Systemd and SysV)

Rotating Expiring Certificates

You must be a Team or Company Manager of your Gremlin account to manage certificates.

All certificates expire one year after creation. Before the expiration date, you must create a new certificate, reconfigure all clients with it, and delete the old certificate. As the expiration date draws near, the Gremlin Web App will display a warning about it.

To create a new certificate, simply click the Create New button next to your existing certificate (see the previous screenshot). Now that you have two certificates, you cannot download the older certificate (though all clients still configured with it may still use it to authenticate), and you cannot create a third certificate.

Two Certificates

If you did not mean to create the newer certificate yet, just destroy it. Otherwise, move all clients to the newer certificate, then destroy the old one.


Can I create one certificate for my whole Company?

No. Every Team within the Company must use its own certificate.

Can I create one certificate per Gremlin client?

No. Every Gremlin client within a Team uses the same shared certificate. When that certificate is about to expire, you must create a new certificate. For a brief time, you may have some clients configured with the older certificate and some with the newer one. But before the older certificate expires, you must move all clients to the newer certificate.

Is it OK for some clients to use secret-based auth while others use signature-based auth?

Yes, but if you are still using secret-based auth, you should move all clients to signature-based auth as soon as possible.

What does signature-based authentication have to do with SSL?

Nothing. Signature-based auth is independent of the SSL layer, but both are important. The purpose of SSL is to 1) encrypt the client-to-server connection, and 2) let the client authenticate the server (i.e. the Gremlin Control Plane). Signature-based auth lets the Gremlin Control Plane authenticate the client.

Before the client connects to the backend, it signs the payload using $GREMLIN_TEAM_PRIVATE_KEY_OR_FILE. Then it initiates an SSL handshake with the backend, verifying the backendโ€™s SSL certificate in the process. After the SSL tunnel has been established the backend verifies that the payload was signed by a Gremlin-issued key.

What cryptographic standard does signature-based authentication use?

It uses 256-bit ECDSA (prime256v1) for keys, with SHA 256-bit ECDSA for signatures. The recommended lifespan for anything secured by these standards is two years, but we are intentionally being more conservative, opting instead for one-year expiration.