SAML (Shibboleth SP)#

This document describes installing Shibboleth on Debian 11.

Installation#

Debian 11#

$ sudo apt install libapache2-mod-shib
$ sudo shib-keygen -n sp-encrypt
$ sudo shib-keygen -n sp-signing

Configuration#

Modify /etc/shibboleth/shibboleth2.xml:

Set entityID to https://vpn.example.org/shibboleth in the <ApplicationDefaults> element.
Set handlerSSL to true and cookieProps to https in the <Sessions> element
Set the entityID to the entity ID of your IdP, or configure the discoveryURL in the <SSO> element
Set the path in the <MetadataProvider> element for a simple static metadata file, e.g.: <MetadataProvider type="XML" validate="false" path="idp.tuxed.net.xml"/> and put the idp.tuxed.net.xml file in /etc/shibboleth. Set validate to false to keep the IdP working in case it has validUntil specified in the XML

Configuring automatic metadata refresh is outside the scope of this document, refer to your identity federation documentation.

Verify the Shibboleth configuration:

$ sudo shibd -t
overall configuration is loadable, check console for non-fatal problems

Restart Shibboleth:

$ sudo systemctl restart shibd

Next: register your SP in your identity federation, or in your IdP. The metadata URL is typically https://vpn.example.org/Shibboleth.sso/Metadata.

Apache#

In /etc/apache2/sites-available/vpn.example.org.conf add the following:

<VirtualHost *:443>

    ...

    <Location /vpn-user-portal>
        AuthType shibboleth
        ShibRequestSetting requireSession 1
        <RequireAll>
            Require shib-session
            #Require shib-attr entitlement "http://eduvpn.org/role/admin"
            #Require shib-attr unscoped-affiliation staff
        </RequireAll>
    </Location>

    # do not restrict API Endpoint as used by VPN clients
    <Location /vpn-user-portal/api>
        Require all granted
    </Location>

    # do not secure OAuth Token Endpoint as used by VPN clients
    <Location /vpn-user-portal/oauth/token>
        Require all granted
    </Location> 

    # If you run separete node(s) you MUST allow access to "node-api.php" 
    # withouh protecting it with Shibboleth
    #<Location /vpn-user-portal/node-api.php>
    #    Require all granted
    #</Location>

    ...

    </VirtualHost>

If you have a case where only one attribute needs to match, you can use <RequireAny>instead of <RequireAll>. You will also need to remove the Require shib-session.

Make sure you restart Apache after changing the configuration:

$ sudo systemctl restart apache2

NOTE if you are using IDs such as entitlement and unscoped-affiliation make sure they are correctly enabled/set in /etc/shibboleth/attribute-map.xml.

Portal#

In order to configure the VPN portal, modify /etc/vpn-user-portal/config.php and set the authModule and ShibAuthModule options:

'authModule' => 'ShibAuthModule',

'ShibAuthModule' => [
    'userIdAttribute' => 'uid',
    'permissionAttributeList' => ['entitlement'],
],

The mentioned attributes persistent-id and entitlement are configured in the Shibboleth configuration. Modify/add others as required in /etc/shibboleth/attribute-map.xml. Do not forget to restart Shibboleth if you make any changes to its configuration.