56 lines
2.5 KiB
Markdown
56 lines
2.5 KiB
Markdown
# Machine-to-machine authentication
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Client credentials can be used for machine-to-machine communication authentication. Clients can authenticate themselves using service-accounts; standard client_id + client_secret is not sufficient. This behavior is due to providers only being able to have a single secret at any given time.
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Note that authentik does treat a grant type of `password` the same as `client_credentials` to support applications which rely on a password grant.
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### Static authentication
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Hence identification is based on service-accounts, and authentication is based on App-password tokens. These objects can be created in a single step using the *Create Service account* function.
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An example request can look like this:
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```
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POST /application/o/token/ HTTP/1.1
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Host: authentik.company
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Content-Type: application/x-www-form-urlencoded
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grant_type=client_credentials&
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client_id=application_client_id&
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username=my-service-account&
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password=my-token
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```
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This will return a JSON response with an `access_token`, which is a signed JWT token. This token can be sent along requests to other hosts, which can then validate the JWT based on the signing key configured in authentik.
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### JWT-authentication
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Starting with authentik 2022.4, you can authenticate and get a token using an existing JWT.
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(For readability we will refer to the JWT issued by the external issuer/platform as input JWT, and the resulting JWT from authentik as the output JWT)
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To configure this, the certificate used to sign the input JWT must be created in authentik. The certificate is enough, a private key is not required. Afterwards, configure the certificate in the OAuth2 provider settings under *Verification certificates*.
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With this configure, any JWT issued by the configured certificates can be used to authenticate:
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```
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POST /application/o/token/ HTTP/1.1
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Host: authentik.company
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Content-Type: application/x-www-form-urlencoded
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grant_type=client_credentials&
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client_assertion_type=urn:ietf:params:oauth:client-assertion-type:jwt-bearer&
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client_assertion=$inputJWT&
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client_id=application_client_id
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```
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Alternatively, you can set the `client_secret` parameter to the `$inputJWT`, for applications which can set the password from a file but not other parameters.
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Input JWTs are checked to be signed by any of the selected *Verification certificates*, and their `exp` attribute must not be now or in the past.
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To do additional checks, you can use *[Expression policies](../../policies/expression)*:
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```python
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return request.context["oauth_jwt"]["iss"] == "https://my.issuer"
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```
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