Authentication/SAML

Zimbra Single Sign-On using SAML with SimpleSAMLphp

   KB 20404        Last updated on 2021-02-22  




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ZCS 9.0 Article ZCS 9.0

Did you know that Zimbra support SAML single sign on? SAML is an open standard that allows you to have a single login page for all applications in your organization. SAML is a Zimbra Network Edition feature. Once you have set-up your SAML portal you can easily add Multi Factor Authentication.

Set up Zimbra SP in SimpleSAMLphp

In SAML terms applications are called Service Providers or SP’s. The service that provides your user database and takes care of your authentication is in SAML terms called Identity Provider or IDP. Usually you only have one IDP and as many SP’s as you have applications. In this example we will set-up Zimbra as a SAML SP and use SimpleSAMLphp as IDP. This is the configuration needed on SimpleSAMLphp (in /etc/simplesamlphp/metadata/saml20-sp-remote.php):

     $metadata['https://zm-zimbra9.barrydegraaff.tk/service/extension/samlreceiver'] = array(
         'simplesaml.attributes'     => true,
            'debug' => TRUE,
             'AssertionConsumerService' => 'https://zm-zimbra9.barrydegraaff.tk/service/extension/samlreceiver',
             'SingleLogoutService' => 'https://zm-zimbra9.barrydegraaff.tk/service/extension/samlslo',
             'NameIDFormat' => 'urn:oasis:names:tc:SAML:1.1:nameid-format:emailAddress',
             'authproc' => array (
                     10 => array(
             'class' => 'saml:AttributeNameID',
             'attribute' => 'emailAddress',
             'Format' => 'urn:oasis:names:tc:SAML:1.1:nameid-format:emailAddress',
              ),
          )
     );

You will also need to get the X.509 public certificate that is used for signing the SAML request from th IDP to Zimbra. You will need to download it and save it on your Zimbra server. This guide will assume you store your cert in /tmp/idpcert.pem, don’t forget to chown zimbra:zimbra /tmp/idpcert.pem. If you followed the SimpleSAMLphp setup guide you can find the certificate at /etc/simplesamlphp/cert/server.crt.

Set up Zimbra

Add the file /opt/zimbra/conf/saml/saml-config.properties to configure SAML in Zimbra add the contents:

     # Issuer
     saml_sp_entity_id=https://zm-zimbra9.barrydegraaff.tk/service/extension/samlreceiver
     # Login receiver for the service provider
     saml_acs=https://zm-zimbra9.barrydegraaff.tk/service/extension/samlreceiver
     # Name ID format for the IDP to use in the SAMLResponse
     saml_name_id_format=urn:oasis:names:tc:SAML:1.1:nameid-format:emailAddress
     # Date format for issue instant
     saml_date_format_instant=yyyy-MM-dd'T'HH:mm:ss'Z'
     # Identity provider login endpoint for redirect method
     saml_redirect_login_destination=https://saml.barrydegraaff.tk/simplesaml/saml2/idp/SSOService.php?spentityid=https://zm-zimbra9.barrydegraaff.tk/service/extension/samlreceiver
     # Identity provider login endpoint for POST method
     saml_post_login_destination=
     # Identity provider logout endpoint for redirect method
     saml_redirect_logout_destination=https://saml.barrydegraaff.tk/simplesaml/saml2/idp/SingleLogoutService.php
     # Identity provider logout endpoint for POST method
     saml_post_logout_destination=
     # Logout redirect page if we are the landing page logout endpoint
     saml_landing_logout_redirect_url=/
     # Disable the audience path check
     saml_skip_audience_restriction=true
     # URL to send the user with error_code, error_msg query params. Default results in HTTP error code pages.
     saml_error_redirect_url=
     # The SAML logout document encoding, and SAML login receiver parameter encoding.
     saml_document_encoding=ASCII
     # Set to true to disable the audience path check.
     saml_skip_audience_restriction=false
     # The redirect location to send the user if their Zimbra account is not active.
     saml_inactive_account_redirect_url

From the command line as user root copy the samlextn.jar and set up the IDP certificate like this:

mkdir /opt/zimbra/lib/ext/saml
cp /opt/zimbra/extensions-network-extra/saml/samlextn.jar /opt/zimbra/lib/ext/saml/
su zimbra
cat /tmp/idpcert.pem |xargs -0 zmprov md exampledomain.com zimbraMyoneloginSamlSigningCert
zmprov mcf zimbraCsrfRefererCheckEnabled FALSE
zmmailboxdctl restart

Single logout

In case you need to support SLO initiated from the IDP you need the SLO url: https://zimbraserver.example.com/service/extension/samlslo

Also if you want to trigger the IDP to log-out when the user clicks logout in Zimbra you have to configure Zimbra to use this log-out url: https://zimbraserver.example.com/service/extension/samllogout.

Create users

Your user accounts must be manually created in Zimbra and be available in your IDP user database. It is important that the E-mail attribute in your IDP is set exactly the same as the Zimbra account name. Or the user will not be able to log-in. If it does not work run a tail -f /opt/zimbra/log/* while doing the authentication request and dig through to log to find out what the issue may be. Keywords to grep for: SAML, Audience and assertion.

Configurable Properties saml-config.properties

The samlextn.jar uses a property file located at: ${zimbra_home}/conf/saml/saml-config.properties.

The following properties are supported:

Key Description Default Optional
saml_sp_entity_id Issuer
saml_acs Login receiver for the service provider
saml_redirect_login_destination Identity provider login endpoint for redirect method
saml_redirect_logout_destination Identity provider logout endpoint for redirect method
saml_post_login_destination Identity provider login endpoint for POST method (unused)
saml_post_logout_destination Identity provider logout endpoint for POST method (unused)
saml_name_id_format Name ID format for the IDP to use in the SAMLResponse urn:oasis:names:tc:SAML:1.1:nameid-format:unspecified
saml_date_format_instant Date format for issue instant yyyy-MM-dd'T'HH:mm:ss'Z'
saml_error_redirect_url URL to send the user with error_code, error_msg query params. Default results in HTTP error code pages.
saml_landing_logout_redirect_url Logout redirect landing page if we are the last logout service. /
saml_document_encoding The SAML logout document encoding, and SAML login receiver parameter encoding. ASCII
saml_skip_audience_restriction Set to true to disable the audience path check. false
saml_inactive_account_redirect_url The redirect location to send the user if their Zimbra account is not active. /service/extension/samllogout
Verified Against: Zimbra 9 Date Created: 02/22/2021
Article ID: https://wiki.zimbra.com/index.php?title=Authentication/SAML Date Modified: 2021-02-22



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