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Concepts

How Keycloak Handles Machine-To-Machine Communication

Andrios Robert

• 1 min read

The request hit the API without a human in sight. Two machines spoke, trusted, and exchanged secrets — all under the watch of Keycloak.

Keycloak is an open source identity and access management solution that can issue secure tokens for machine-to-machine (M2M) communication. It removes the need for manual credential sharing, replaces static keys with rotating secrets, and enforces strict access scopes. In M2M scenarios, no browser or human input exists; authentication flows happen entirely over APIs.

How Keycloak Handles Machine-To-Machine Communication

At the core is the OAuth 2.0 client credentials grant type. This allows one service to request an access token directly from Keycloak using its client ID and secret. That token can then be attached to HTTP requests to authenticate against another service. Keycloak’s token endpoint validates the client, issues a JWT, and sets an expiration time. The receiving service verifies the token signature against Keycloak’s public key, ensuring it’s valid and unaltered.

Setting Up in Keycloak

  1. Create a new Client in the Keycloak admin console.
  2. Set Access Type to confidential and enable Service Accounts.
  3. Assign the service account the necessary roles or client scopes.
  4. Use the client ID and secret to call Keycloak’s token endpoint at /protocol/openid-connect/token with grant_type=client_credentials.

The service will receive a signed JWT in the response. The token’s claims will reflect the roles and scopes configured. Services can enforce fine-grained permissions without hardcoding static credentials.

Security Best Practices

  • Rotate client secrets often.
  • Use TLS for all token requests and service calls.
  • Keep token lifetimes short to limit exposure.
  • Restrict scopes to the minimum required for the M2M task.

Why Choose Keycloak for M2M

Keycloak runs anywhere — bare metal, VMs, Kubernetes. It integrates with LDAP, Active Directory, and many SSO providers. It handles token signing, revocation, and introspection without custom code. For distributed systems and microservices, it becomes a single source of truth for identity between machines.

Machine-to-machine communication with Keycloak is faster to secure and easier to scale than building a custom auth flow. Configure once, repeat across services, and maintain centralized control.

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