To get started with machine-to-machine authentication using Ory Kratos, it's important to note that Ory Kratos is primarily focused on identity and user authentication (humans), not service-to-service (machine-to-machine) authentication. For machine-to-machine scenarios, Ory recommends using OAuth2 flows, which are typically handled by Ory Hydra (for OAuth2 and OpenID Connect) rather than Kratos. However, if your use case involves programmatic access to Kratos APIs (for example, managing identities or sessions from a backend service), you can interact with the Kratos Admin API directly. In production, you should secure the Admin API so that only trusted services can access it, typically by running it on a private network or behind a reverse proxy with proper access controls. There is no mention in the knowledge sources of Kratos supporting OAuth2 client credentials or similar machine-to-machine flows natively. For true machine-to-machine authentication (such as issuing and validating access tokens for APIs), you should look at Ory Hydra, which is designed for OAuth2 and OpenID Connect flows, including the client credentials grant for service accounts. You can find more about this in the Ory documentation under "Connect service accounts" and "Implement OAuth flows" [Welcome to Ory!](https://www.ory.sh/docs/welcome/). Summary: - Ory Kratos is for user authentication and identity management. - For machine-to-machine authentication, use Ory Hydra and OAuth2 client credentials flow. - Secure Kratos Admin API access for backend integrations, but this is not a full machine-to-machine auth solution. I'm sorry, but the knowledge sources do not provide a step-by-step guide for machine-to-machine authentication with Ory Kratos itself. For service-to-service authentication, please refer to Ory Hydra and the OAuth2 documentation [Welcome to Ory!](https://www.ory.sh/docs/welcome/).

In the Ory ecosystem, the service responsible for generating authentication tokens or authorization codes depends on the type of authentication flow you are implementing: - For OAuth2 and OpenID Connect flows (including authorization code and client credentials grants): The service that generates authorization codes and tokens is Ory Hydra (or Ory OAuth2 & OpenID Connect in Ory Network). When a client application initiates an OAuth2 flow, Ory Hydra issues the authorization code and, upon exchange, the access and ID tokens. The actual code/token generation is handled by the OAuth2 server, not by the client or a separate service. The client (your app or service) requests these from Ory Hydra by following the appropriate OAuth2 flow (e.g., authorization code flow, client credentials flow) [Run your own OAuth2 Server](https://www.ory.sh/blog/run-oauth2-server-open-source-api-security/) [Try common OAuth2 Grants](https://www.ory.sh/docs/getting-started/ory-network-oauth2/). - For user authentication (login, registration, etc.): Ory Kratos handles user authentication and issues session cookies or tokens after successful login. However, Kratos does not generate OAuth2 authorization codes or access tokens; it is focused on user identity and session management [Ory Ecosystem Introduction](https://www.ory.sh/docs/ecosystem/projects/). Summary: - The OAuth2 server (Ory Hydra) is responsible for generating authorization codes and tokens in OAuth2 flows. - The identity server (Ory Kratos) is responsible for user authentication and session management, not for issuing OAuth2 tokens. If you need to implement machine-to-machine authentication or OAuth2 flows, the service (Ory Hydra) should generate the tokens or codes—not your application or a separate service. Your application should request them from Ory Hydra using the appropriate protocol.