mod_auth_openidc is an authentication/authorization module for the Apache 2.x HTTP server that functions as an OpenID Connect Relying Party, authenticating users against an OpenID Connect Provider. It can also function as an OAuth 2.0 Resource Server, validating OAuth 2.0 bearer access tokens presented by OAuth 2.0 Clients.

This module enables an Apache 2.x web server to operate as an OpenID Connect Relying Party (RP) to an OpenID Connect Provider (OP). It authenticates users against an OpenID Connect Provider, receives user identity information from the OP in a so called ID Token and passes on the identity information (a.k.a. claims) in the ID Token to applications hosted and protected by the Apache web server.

It can also be configured as an OAuth 2.0 Resource Server (RS), consuming bearer access tokens and validating them against an OAuth 2.0 Authorization Server, authorizing Clients based on the validation results.

The protected content and/or applications can be served by the Apache server itself or it can be served from elsewhere when Apache is configured as a Reverse Proxy in front of the origin server(s).

By default the module sets the REMOTE_USER variable to the id_token [sub] claim, concatenated with the OP's Issuer identifier ([sub]@[iss]). Other id_token claims are passed in HTTP headers and/or environment variables together with those (optionally) obtained from the UserInfo endpoint.

It allows for authorization rules (based on standard Apache Require primitives) that can be matched against the set of claims provided in the id_token/ userinfo claims.

mod_auth_openidc supports the following specifications:

• OpenID Connect Core 1.0 (Basic, Implicit, Hybrid and Refresh flows)
• OpenID Connect Discovery 1.0
• OpenID Connect Dynamic Client Registration 1.0
• OAuth 2.0 Multiple Response Type Encoding Practices 1.0
• OAuth 2.0 Form Post Response Mode 1.0
• RFC7 7636 - Proof Key for Code Exchange by OAuth Public Clients
• OpenID Connect Session Management 1.0 (implementers draft; see the Wiki for information on how to configure it)
• OpenID Connect Front-Channel Logout 1.0 (implementers draft)
• Encoding claims in the OAuth 2 state parameter using a JWT (draft spec)
• OpenID Connect Token Bound Authentication (draft spec; when combined with mod_token_binding)

Alternatively the module can operate as an OAuth 2.0 Resource Server to an OAuth 2.0 Authorization Server, validating bearer Access Tokens by introspecting them or verifying them locally if they are JWTs. In the OAuth 2.0 Resource Server mode mod_auth_openidc supports the following specifications:

• RFC 6750 - The OAuth 2.0 Authorization Framework: Bearer Token Usage
• RFC 7662 - OAuth 2.0 Token Introspection (or similar)
• RFC 8414 - OAuth 2.0 Authorization Server Metadata

The REMOTE_USER variable setting, passing claims in HTTP headers and authorization based on Require primitives works in the same way as described for OpenID Connect above. See the Wiki for information on how to configure it.

For an exhaustive description of all configuration options, see the file auth_openidc.conf in this directory. This file can also serve as an include file for httpd.conf.

For generic questions, see the Wiki pages with Frequently Asked Questions at:
https://github.com/zmartzone/mod_auth_openidc/wiki
There is a Google Group/mailing list at:
mod_auth_openidc@googlegroups.com
The corresponding forum/archive is at:
https://groups.google.com/forum/#!forum/mod_auth_openidc
Any questions/issues should go to the mailing list. The Github issues tracker should be used only for bugs reports and feature requests.

For commercial Support contracts, Professional Services, Training and use-case specific support you can contact:
sales@zmartzone.eu

Sample configuration for using Google as your OpenID Connect Provider running on www.example.com and https://www.example.com/example/redirect_uri registered as the redirect_uri for the client through the Google API Console. You will also have to enable the Google+ API under APIs & auth in the Google API console.

OIDCProviderMetadataURL https://accounts.google.com/.well-known/openid-configuration
OIDCClientID <your-client-id-administered-through-the-google-api-console>
OIDCClientSecret <your-client-secret-administered-through-the-google-api-console>

# OIDCRedirectURI is a vanity URL that must point to a path protected by this module but must NOT point to any content
OIDCRedirectURI https://www.example.com/example/redirect_uri
OIDCCryptoPassphrase <password>

<Location /example/>
   AuthType openid-connect
   Require valid-user
</Location>

Note if you want to securely restrict logins to a specific Google Apps domain you would not only add the hd=<your-domain> setting to the OIDCAuthRequestParams primitive for skipping the Google Account Chooser screen, but you must also ask for the email scope using OIDCScope and use a Require claim authorization setting in the Location primitive similar to:

OIDCScope "openid email"
Require claim hd:<your-domain>

The above is an authorization example of an exact match of a provided claim against a string value. For more authorization options see the Wiki page on Authorization.

See also the Wiki page on Keycloak

OIDCProviderMetadataURL https://keycloak.example.net/auth/realms/master/.well-known/openid-configuration
# OIDCRedirectURI is a vanity URL that must point to a path protected by this module but must NOT point to any content
OIDCRedirectURI https://www.example.net/oauth2callback
OIDCCryptoPassphrase random1234
OIDCClientID <your-client-id-registered-in-keycloak>
OIDCClientSecret <your-client-secret-registered-in-keycloak>
OIDCRemoteUserClaim email
OIDCScope "openid email"

<Location /example/>
   AuthType openid-connect
   Require valid-user
</Location>

1. install and load mod_auth_openidc.so in your Apache server
2. configure your protected content/locations with AuthType openid-connect
3. set OIDCRedirectURI to a "vanity" URL within a location that is protected by mod_auth_openidc
4. register/generate a Client identifier and a secret with the OpenID Connect Provider and configure those in OIDCClientID and OIDCClientSecret respectively
5. and register the OIDCRedirectURI as the Redirect or Callback URI with your client at the Provider
6. configure OIDCProviderMetadataURL so it points to the Discovery metadata of your OpenID Connect Provider served on the .well-known/openid-configuration endpoint
7. configure a random password in OIDCCryptoPassphrase for session/state encryption purposes

LoadModule auth_openidc_module modules/mod_auth_openidc.so

OIDCProviderMetadataURL <issuer>/.well-known/openid-configuration
OIDCClientID <client_id>
OIDCClientSecret <client_secret>

# OIDCRedirectURI is a vanity URL that must point to a path protected by this module but must NOT point to any content
OIDCRedirectURI https://<hostname>/secure/redirect_uri
OIDCCryptoPassphrase <password>

<Location /secure>
   AuthType openid-connect
   Require valid-user
</Location>

For details on configuring multiple providers see the Wiki.

Using "local" validation of JWT bearer tokens:

1. install and load mod_auth_openidc.so in your Apache server
2. configure your protected APIs/locations with AuthType oauth20 and Require claim directives to restrict access to specific clients/scopes/claims/resource-owners
3. configure local or remote bearer token validation following the Wiki

# local validation
OIDCOAuthVerifySharedKeys plain##<shared-secret-to-validate-symmetric-jwt-signatures>

<Location /api>
   AuthType oauth20
   Require claim sub:<resource_owner_identifier>
</Location>

This software is open sourced by ZmartZone IAM. For commercial services you can contact ZmartZone IAM as described above in the Support section.