[[_mod_auth_mellon]] === mod_auth_mellon Apache HTTPD Module The https://github.com/UNINETT/mod_auth_mellon[mod_auth_mellon] is an Apache HTTPD plugin for SAML. If your language/environment supports using Apache HTTPD as a proxy, then you can use mod_auth_mellon to secure your web application with SAML. For more details on configuration of this adapter see the _mod_auth_mellon_ Github repo. To configure mod_auth_mellon you'll need: * An Identity Provider (IdP) entity descriptor XML file, which describes the connection to {{book.project.name}} or another SAML IdP * An SP entity descriptor XML file, which describes the SAML connections and configuration for the application you are securing. * A private key PEM file, which is a text file in the PEM format that defines the private key the application uses to sign documents. * A certificate PEM file, which is a text file that defines the certificate for your application. * mod_auth_mellon-specific Apache HTTPD module configuration. If you have already defined and registered the client application within a realm on the {{book.project.name}} application server, {{book.project.name}} can generate all the files you need except the Apache HTTPD module configuration. To do this, complete the following steps: . Go to the *Installation* page of your SAML client and select the *Mod Auth Mellon files* option. + .mod_auth_mellon config download image:../../{{book.images}}/mod-auth-mellon-config-download.png[] . Click *Download* to download a zip file that contains the XML descriptor and PEM files you need. New content start: === Configuring mod_auth_mellon with Red Hat Single Sign-On There are two hosts involved: *The host on which Red Hat Single Sign-On is running, which will be referred to as $idp_host because Red Hat Single Sign-On is a SAML Identity Provider (IdP). *The host on which the web application is running, which will be referred to as $sp_host. In SAML an application using an IdP is called a Service Provider (SP). All of the following steps need to performed on $sp_host with root privileges. ==== Installing the Packages You need to install the necessary packages. To do this, you will need: * Apache Web Server (httpd) * Mellon SAML SP add-on module for Apache * Tools to create X509 certificates To install the necessary packages, run this command: yum install httpd mod_auth_mellon mod_ssl openssl ==== Creating a Configuration Directory for Apache SAML It is advisable to keep configuration files related to Apache's use of SAML in one location. To create a new directory saml2 located under the Apache configuration root /etc/httpd: mkdir /etc/httpd/saml2 ==== Configuring the Mellon Service Provider Configuration files for Apache add-on modules are located in the directory /etc/httpd/conf.d and have a file name extension of .conf. You need to add the file /etc/httpd/conf.d/mellon.conf and place Mellon's configuration directives in it. Mellon's configuration directives can roughly be broken down into two classes of information: * Which URLs to protect with SAML authentication * What SAML parameters will be used when a protected URL is referenced. Apache configuration directives typically follow a hierarchical tree structure in the URL space, which are known as locations. You will need to specify one or more URL locations that Mellon protects. You have flexibility in how you add the configuration parameters that apply to each location. You can either add all the necessary parameters to the location block or you can add Mellon parameters to a common location high up in the URL location hierarchy that specific protected locations inherit (or some combination of the two). Since it is common for an SP to operate in the same way no matter which location triggers SAML actions, the example configuration used here places common Mellon configuration directives in the root of the hierarchy and then specific locations to be protected by Mellon can be defined with minimal directives. This strategy avoids duplicating the same parameters for each protected location. This example will have just one protected location: https://$sp_host/protected. To configure the Mellon service provider, complete the following steps: . Create the file /etc/httpd/conf.d/mellon.conf with this content: MellonEnable info MellonEndpointPath /mellon/ MellonSPMetadataFile /etc/httpd/saml2/mellon_metadata.xml MellonSPPrivateKeyFile /etc/httpd/saml2/mellon.key MellonSPCertFile /etc/httpd/saml2/mellon.crt MellonIdPMetadataFile /etc/httpd/saml2/idp_metadata.xml AuthType Mellon MellonEnable auth Require valid-user Note: Some of the files referenced in the above code are created in later steps. ==== Creating the Service Provider Metadata In SAML IdPs and SPs learn about each other by exchanging SAML metadata. SAML metadata is in XML format. The schema for the metadata is a standard thus assuring participating SAML entities can consume each other's metadata. You need: * Metadata for the IdP the SP utilizes * Metadata describing the SP provided to the IdP One of the components of SAML metadata is X509 certificates. These certificates are used for two purposes: * Sign SAML messages so the other end can prove the message originated from the expected party. * Encrypt the message during transport (seldom used because SAM messages typically occur on TLS-protected transports) You can use your own certificates if you already have a Certificate Authority (CA) or you can generate a self-signed certificate. For simplicity in this example a self-signed certificate is used. Because Mellon's SP metadata must reflect the capabilities of the installed version of mod_auth_mellon, must be valid SP metadata XML, and must contain an X509 certificate (whose creation can be obtuse unless you are familiar with X509 certificate generation) the most expedient way to produce the SP metadata is to use a tool included in the mod_auth_mellon package (mellon_create_metadata.sh). The generated metadata can always be edited later because it is a text file. The tool also creates your X509 key and certificate. SAML IdPs and SPs identify themselves using a unique name known as an EntityID. To use the Mellon metadata creation tool you need: * The EntityID, which is typically the URL of the SP, and often the URL of the SP where the SP metadata can be retrieved * The URL where SAML messages for the SP will be consumed, which Mellon calls the MellonEndPointPath. The following steps : . Create a few helper shell variables . Invoke the Mellon metadata creation tool . Move the generated files to their destination (referenced in /etc/httpd/conf.d/mellon.conf created above). Do this: fqdn=`hostname` mellon_endpoint_url="https://${fqdn}/mellon" mellon_entity_id="${mellon_endpoint_url}/metadata" file_prefix="$(echo "$mellon_entity_id" | sed 's/[^A-Za-z.]/_/g' | sed 's/__*/_/g')" /usr/libexec/mod_auth_mellon/mellon_create_metadata.sh $mellon_entity_id $mellon_endpoint_url mv ${file_prefix}.cert /etc/httpd/saml2/mellon.crt mv ${file_prefix}.key /etc/httpd/saml2/mellon.key mv ${file_prefix}.xml /etc/httpd/saml2/mellon_metadata.xml ==== Adding the Mellon Service Provider to the Red Hat Single Sign-On Identity Provider Assumption: The Red Hat Single Sign-On IdP has already been installed on the $idp_host. Red Hat Single Sign-On supports multiple tenancy where all users, clients, and so on are grouped in what is called a realm. Each realm is independent of other realms. You can use an existing realm in your Red Hat Single Sign-On but for this example we will create a new realm called test_realm and utilize that. All these operations are performed using the Red Hat Single Sign-On administration web console. You need to know the admin username and password for $idp_host. Perform these steps: . Open the Admin Console and log on by entering the admin username and password. + After logging into the admin console there will be an existing realm. When Red Hat Single Sign-On is first set up a root realm, master, is created by default. Any previously created realms are listed in the upper left corner of the admin console in a drop-down list. . From the realm drop-down list select *Add realm*. . In the Name field type `test_realm` and click *Create*. ==== Adding the Mellon Service Provider as a Client of the Realm In Red Hat Single Sign-On SAML SPs are known as clients. To add the SP we must be in the Clients section of the realm. . Click the Clients menu item on the left and click *Create* in the upper right corner to create a new client. Add the Mellon SP Client You will need to: . Set the client protocol to SAML by selecting *saml* from the Client Protocol drop down list. . Provide the Mellon SP metadata file we created above (/etc/httpd/saml2/mellon_metadata.xml). Depending on where you are running your browser from you might have to copy the SP metadata from from $sp_host to the machine you're running your browser on so the browser can find the file. . Click *Save*. Edit the Client There are several client configuration parameters we suggest setting: * Make sure "Force POST Binding" is On * Add paosResponse to the Valid Redirect URIs list: . Copy the postResponse URL in "Valid Redirect URIs" and paste it into the empty add text fields just below the "+". . Change "postResponse" to "paosResponse". (The paosResponse URL is needed for SAML ECP.) . Click *Save* at the bottom. Many SAML SPs determine authorization based on a user's membership in a group. The Red Hat Single Sign-On IdP can manage user group information but it won't supply the user's groups unless the IdP is configured to supply it as a SAML attribute. To configure the IdP to supply the user's groups as as a SAML attribute, complete the following steps: . Click the Mappers tab of the client. . In the upper right corner of the Mappers page, click *Create*. . From the Mapper Type drop-down list select *Group list*. . Set Name to "group list." . Set the SAML attribute name to "groups." . Click *Save.* The remaining steps are performed on $sp_host. ==== Retrieving the Identity Provider Metadata Now that you have created the realm on the IdP you need to retrieve the IdP metadata associated with it so the Mellon SP knows about it. In the /etc/httpd/conf.d/mellon.conf file created previously, the MellonIdPMetadataFile is specified as /etc/httpd/saml2/idp_metadata.xml but until now that file has not existed on $sp_host. To get that file we will retrieve it from the IdP. . Do this by substituting $idp_host with the correct value: curl -k -o /etc/httpd/saml2/idp_metadata.xml \ https://$idp_host/auth/realms/test_realm/protocol/saml/descriptor + Mellon is now fully configured. . To run a syntax check for Apache configuration files: apachectl configtest + Note: configtest is equivalent to the -t argument to apachectl. If the configuration test shows any errors, correct them before proceeding. . Restart the Apache server: systemctl restart httpd.service You've now setup both Red Hat Single Sign-On as a SAML IdP in the test_realm and mod_auth_mellon as SAML SP protecting the URL $sp_host/protected (and everything beneath it) by authenticating against the $``$idp_host`` IdP.