todo: need Apache version 2.4.10 or higher so that the local address request field gets populated.

todo: For ajp, add prefix in shib2.xml,     add permitted pattern in 8009 connector in server.xml

See: https://shibboleth.atlassian.net/wiki/spaces/SP3/pages/2067400159/JavaHowTo

See https://stackoverflow.com/questions/63505670/apache-cant-connect-to-new-tomcat-9-ajp

Very Basic Overview

IdP (Identity Provider): A web-based system that can authenticate a user on behalf of another system called SP (for Service Provider).

In this implementation of SSO, the SP consists of the Shibboleth SP version 3 software. See https://shibboleth.atlassian.net/wiki/spaces/SP3/overview .

Upon successful login at the IdP, the IdP will send information about the user back to the SP as "attributes".

Among other things, The SP must be configured to specify which of these attributes should be passed to the shrine code (in the form of request headers).

Installation Layout

The following instructions assume that (1) you are using Tomcat as your application server, and (2) Apache and Tomcat are running on the same host.

Ideally the following layout is used:

/opt/shrine/tomcat ← Tomcat home

/etc/shibboleth ← Shibboleth configuration files

/etc/httpd/* ← Apache configuration files

 /var/www/html ← Apache static content as set in, for instance, /etc/httpd/conf/httpd.conf

Quick Instructions for Adjusting Configuration and Getting Going 

The following instructions are meant to get you going as quickly as possible. If you want a better understanding of what's going on, go to the next section of this document.

Among the many configuration files, there are eight which need to be modified to reflect your installation, as follows:

Each of these files needs to be adjusted to the particulars of your site, your requirements. 

You can search for the marker: 'ADJUST_FOR_YOUR_SITE' in those files for indications of what / where you need to edit.

More-Detailed Discussion of Shibboleth, Apache, and Tomcat Configuration

Here we discuss key items in the various configuration files; not necessarily the items that need to be modified but those that deserve an explanation.

Apache Configuration

/etc/httpd/conf.d/sp.conf

ServerName should be set to your SP host's name, for instance my-shibboleth-sp-host.net:

ServerName shrine-sso-node01.catalyst.harvard.edu

The following tells Apache to proxy all calls to a URL starting with "shrine-api" to http://127.0.0.1:8080/shrine-api/. Therefore we need to set up Tomcat to listen for HTTP traffic on port 8080 (see Tomcat Configuration below)

ProxyPassReverse "/shrine-api/" "http://127.0.0.1:8080/shrine-api/"
ProxyPass "/shrine-api/" "http://127.0.0.1:8080/shrine-api/"

The following tells Apache to use Shibboleth for authentication for any URL starting with "shrine-api":

<LocationMatch "/shrine-api/">
  AuthType shibboleth
  ShibRequestSetting requireSession 1
  Require valid-user local

The following tells Shibboleth to make the attributes it collects from the IdP available as request headers in Apache. This is the opposite of what is recommended, i.e. the Shibboleth documentation says that ideally ShibUseEnvironment should be On (resulting in request attributes) and ShibUseHeaders should be Off. However the recommended setup requires proxying to Tomcat using the AJP protocol, which we are not using because it is being phased out of Tomcat (so we are proxying using the HTTP protocol). Also, see https://shibboleth.atlassian.net/wiki/spaces/SHIB2/pages/2577072327/NativeSPApacheConfig.

  ShibUseEnvironment Off

  ShibUseHeaders On

</LocationMatch>

Shibboleth Configuration

Shibboleth consists of a Daemon plus an apache module. This Apache module must be configured for Shibboleth to intercept certain requests (see Apache Configuration above). When a request is intercepted, Shibboleth will decide whether the user (1) needs to login at the configured IdP (which will present a login form to the user), or (2) is already logged in (and Shibboleth will let the request be served as if it wasn't there to intercept it)

/etc/shibboleth/shibboleth2.xml

entityID: the ID of our Service Provider (SP)

REMOTE_USER: how the REMOTE_USER attribute will be populated, in the form of a list of attribute names. Note that "ecommonsid" which is specific to HMS IT, comes first, so for this environment REMOTE_USER will be set to the value of "ecommonsid". Otherwise, the first attribute name from the list which matches the name of an attribute returned by the IdP will be used. "attributePrefix" must be set to "AJP_" so that the attributes from the "attribute-map.xml" file (see below) will be passed to Tomcat as request attributes (as opposed to request headers). See also server.xml on the same topic.

    <ApplicationDefaults entityID="https://shrine-sso-node01.catalyst.harvard.edu"
                         REMOTE_USER="ecommonsid eppn uid persistent-id targeted-id"
                         signing="true"
                         attributePrefix="AJP_"
    >

Sessions configuration documentation is available at https://shibboleth.atlassian.net/wiki/spaces/SP3/pages/2065334342/Sessions

<!--
Controls session lifetimes, address checks, cookie handling, and the protocol handlers.
You MUST supply an effectively unique handlerURL value for each of your applications.
The value defaults to /Shibboleth.sso, and should be a relative path, with the SP computing
a relative value based on the virtual host. Using handlerSSL="true", the default, will force
the protocol to be https. You should also set cookieProps to "https" for SSL-only sites.
Note that while we default checkAddress to "false", this has a negative impact on the
security of your site. Stealing sessions via cookie theft is much easier with this disabled.
-->
<Sessions lifetime="28800" timeout="3600" relayState="ss:mem"
checkAddress="false" handlerSSL="true" cookieProps="https">

The following specifies the entityID of the IdP to use for authentication. We also specify that we speak only SAML2 protocol.

            <SSO entityID="http://sso.med.harvard.edu/adfs/services/trust">
                SAML2
            </SSO>

When logging out, only log out of the local Shibboleth session.

<Logout>Local</Logout>

Setting the status-reporting-service to "/Shibboleth.sso/Status"

<Handler type="Status" Location="/Status"/>

Setting the session diagnostic service to "/Shibboleth.sso/Session"

<Handler type="Session" Location="/Session" showAttributeValues="true"
contentType="application/json"
/>

The IdP's metadata is stored in a file called idp-metadata.xml. It should be obtained from the IdP admin/maintainer.

<MetadataProvider type="XML" validate="true" path="idp-metadata.xml"/>

The attribute-map.xml file will specify which attributes are extracted from the IdP's response and the name of the request headers they will be available as (to the java code). More on this file later.

<AttributeExtractor type="XML" validate="true" reloadChanges="false" path="attribute-map.xml"/>

We left this and the file it points to unchanged:

<AttributeResolver type="Query" subjectMatch="true"/>
<AttributeFilter type="XML" validate="true" path="attribute-policy.xml"/>

This points to the key pair we created above:

<CredentialResolver type="File" key="/etc/shibboleth/sp-key.pem" certificate="/etc/shibboleth/sp-cert.pem"/>

We left this and the file it points to unchanged:

<SecurityPolicyProvider type="XML" validate="true" path="security-policy.xml"/>
<ProtocolProvider type="XML" validate="true" reloadChanges="false" path="protocols.xml"/>

Our Shibboleth configuration has been pared down to the essential ( ? ). If needed, for instance if we want to add functionality to our Shibboleth installation, refer to shibboleth2.xml.dist

File idp-metadata.xml

Get from your IdP (Probably do not (need to) distribute ours)

File attribute-map.xml

<Attributes xmlns="urn:mace:shibboleth:2.0:attribute-map" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">

    
    <!--    The 'name' attributes need to match exactly what your IdP sends in 
            its response to your (successful) AuthnRequest
            
            E.g.
    -->
    <Attribute name="ecommonsId" id="ecommonsid"/>
    <Attribute name="Email" id="email"/>
    <Attribute name="Firstname" id="firstname"/>
    <Attribute name="Lastname" id="lastname"/>

</Attributes>

Tomcat Configuration

Tomcat should accept requests on port 8080, but only from localhost, and redirect to the SSL port 6443:

<Connector port="8080" protocol="HTTP/1.1"

               connectionTimeout="20000"

               address="127.0.0.1"

               redirectPort="6443" />

Configure port 6443:

    <Connector port="6443" protocol="org.apache.coyote.http11.Http11NioProtocol"
               maxThreads="150" SSLEnabled="true" scheme="https" secure="true">
        <SSLHostConfig clientAuth="none" sslProtocol="TLS" sslEnabledProtocols="TLSv1.3,TLSv1.2"
               honorCipherOrder="true" ciphers="TLS_AES_256_GCM_SHA384,TLS_AES_128_GCM_SHA256,
               TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256,TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384,
               TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256">
            <Certificate certificateKeystoreFile="/opt/shrine/shrine.keystore"
                         certificateKeystorePassword="changeit"
                         certificateKeyAlias="*.catalyst.harvard.edu" />
        </SSLHostConfig>
    </Connector>

Configure the AJP connector. Note the "allowedRequestAttributesPattern=".*" attribute. That is needed for the AJP connection so that the attributes from the "attribute-map.xml" file (see above) will be passed to the ServletRequest object as request attributes (as opposed to request headers). See also shibboleth2.xml on the same topic.

<Connector protocol="org.apache.coyote.ajp.AjpNio2Protocol" 
               proxyName="shrine-sso-node01"
               enableLookups="true"
               address="0.0.0.0"
                allowedRequestAttributesPattern=".*"
               port="8009" 
               secretRequired="false"
               redirectPort="6443" />

File sp-metadata.xml

The entityId attribute specifies who we are

<!-- ADJUST_FOR_YOUR_SITE (EntityDescriptor-entityID) -->
  <md:EntityDescriptor xmlns:md="urn:oasis:names:tc:SAML:2.0:metadata" xmlns:ds="http://www.w3.org/2000/09/xmldsig#" entityID="https://shrine-sso-node01.catalyst.harvard.edu">
    <md:SPSSODescriptor AuthnRequestsSigned="true" WantAssertionsSigned="true" protocolSupportEnumeration="urn:oasis:names:tc:SAML:2.0:protocol">
      <md:KeyDescriptor>
        <ds:KeyInfo>
          <ds:X509Data>
            <!-- ADJUST_FOR_YOUR_SITE (X509Certificate) →

The certificate contains the public key that was generated earlier

            <ds:X509Certificate>MIIC6zCCAdOgAwIBAgIJAOy0nki3WAOVMA0GCSqGSIb3DQEBBQUAMBcxFTATBgNV

BAMTDDc5OTQzZmVlNzg2NTAeFw0xNTEyMTEwMzAwNDJaFw0yNTEyMDgwMzAwNDJa                 

MBcxFTATBgNVBAMTDDc5OTQzZmVlNzg2NTCCASIwDQYJKoZIhvcNAQEBBQADggEP

ADCCAQoCggEBALPBzAz0DTn+j2YsQKfqWI+m08lP5UzwVsE9ZKzLqO3PRHZqiOBm

EaFmRrYCZCAOcJ0TXcxPGtNSo8HC4uw5/Y5lJGuI3jN7X7KB1VUQDpUSwfgOqtro

uDoVRKrsaYZTnlNV8KbZ0WQz5s4Uw6CxKRB9RZ5iQMP1fuxc8B6GSOb3x69MiY6c

1jlgVAc6rV4zGfpafacxOLM8qcYhY8u3TiSd0H+oiGEqi1mFLK8yp6FKzX8OUkQf

We49YHz6wBxFOe+/p+7ziym1rBs/lGfenEo8ziCIMmjnoo257fz00bcz9rFl1rTx

KLFfgy72xTlG72l6u+pB9VqK3YNJS52Ns5UCAwEAAaM6MDgwFwYDVR0RBBAwDoIM

Nzk5NDNmZWU3ODY1MB0GA1UdDgQWBBRiDMNPjiAMC50WWubI3PMjP45S/DANBgkq

hkiG9w0BAQUFAAOCAQEAYZM/iWgC93vAq0d98egEzvESKodxHffkDOagd4Kxt/S0

AAHsVQCmAK/9kmRhsWzR3f1KIw98q4EX7nH/K68BFrerUvaL5+fEGE9W6Ki6QdW8

bM17GQkLyRDKZzGPm/hsaG1Oxru2kDf7qSvv59aRZlZ8skrDEnx8+dZ8JKC02ZDU

ClC+xWl1UPfO2BL4tJei/siSymGpiRqznQ2JMoTFu5CUUpoxyCVz1bl9lCVceoJ9

FaL38knS0p5DnXcm+I8wqNEVGLDPbDalBQryhJT9fIMm1/B85gB3AWAvcu9PPfHK

lQQUhxyEXTBJx3luLlpIjoloFKIute9K7pE5qAENjg== </ds:X509Certificate>
          </ds:X509Data>
        </ds:KeyInfo>
      </md:KeyDescriptor>
    <!-- ADJUST_FOR_YOUR_SITE (ssertionConsumerService-Location) -->
    <!-- NB: Adjust the host, but keep the /Shibboleth.sso... -->

the "Location" attribute specifies the URL at which the IdP will post the user info after a successful login:

    <md:AssertionConsumerService Binding="urn:oasis:names:tc:SAML:2.0:bindings:HTTP-POST" Location="https://shrine-sso-node01.catalyst.harvard.edu/Shibboleth.sso/SAML2/POST" index="1"/>
  </md:SPSSODescriptor>
</md:EntityDescriptor>

Developer tools

• SAML : "SAML DevTools extension" for Chrome

Appendix: a Decent Book

Stefan Rasmusson: "SAML 2.0; Designing Secure Identity Federation"