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This appendix is designed to guide system admins installing Single-Sign-On (SSO) for Shrine (using Shibboleth).
Very Basic Overview of SSO
IdP
Installation Layout
The following instructions assume that Apache and Tomcat (or your application server) are running on the same host.
Quick Shibboleth Instructions for Adjusting Configuration
For Shibboleth, we are using SP-3. See https://shibboleth.atlassian.net/wiki/spaces/SP3/overview .
Consult your local Shibboleth experts for guidance.
In the present case, the SP consists of the Shibboleth SP software.
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(Identity Provider): A web-based system that can authenticate a user on behalf of another system
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called a SP
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(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 idPIdP, the idP IdP will send information about the user (at least, "remote_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 (we are not using request attributes because that necessitates the use of AJP, which is being phased out of Tomcat).
There are five configuration files that need to go on the host that is running shibd (Shibboleth SP). They will be installed upon installing Shibboleth SP, and they need to be overlayed/modified to reflect your installation, as follows:
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/etc/shibboleth/idp-metadata.xml
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/var/www/html/sp-metadata.xml
– if your Apache sets DocumentRoot to /var/www/html (for instance in /etc/httpd/conf/httpd.conf)
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To be shared dynamically with your site's Shibboleth IdP (i.e. make it available at a given URL and share that URL with your idP's maintainers/admins)
Or omit from the SP, and instead email it to the IdP admins
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Tells Apache to require Shibboleth login for Shrine Urls (/shrine-api/*) .
Tomcat should open port 8080 only to localhost, and should reside on the same host as your SP
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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 Considerations
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 shibbolethShibRequestSetting requireSession 1Require valid-user local
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HTTP servlet request attributes and/or headers).
Shibboleth config Documentation
This is not required reading, but if you want to jump in depth, this is the official Shibboleth configuration documentation
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https://shibboleth.atlassian.net/wiki/spaces/
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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. 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
--------------------------- make it generic! ----------------------------------
- entityID: the ID of our Service Provider (SP)
- REMOTE_USER: how REMOTE_USER will be populated. Note that "ecommonsid which is specific to HMS IT, comes first, so REMOTE_USER will be set to its value). Otherwise, the first attribute name that matches an attribute returned by the idP will be used.
- The sessionHook is the URL of code running on Tomcat. It will run before Shibboleth redirects the user to the wanted URL after the user authenticates. More on this later.
<ApplicationDefaults entityID="https://shrine-sso-node01.catalyst.harvard.edu"
REMOTE_USER="ecommonsid eppn uid persistent-id targeted-id"
signing="true"
>
<!--
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.
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When logging out, only log out of the local Shibboleth session.
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Setting the status-reporting-service to "/Shibboleth.sso/Status"
<Handler type="Status" Location="/Status"/>
Setting the session diagnostic service to "/Shibboleth.sso/Session"
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Developer tools
- SAML : "SAML DevTools extension" for Chrome. These tools let you view encoded SAML content.
A Decent Book on SAML
- Stefan Rasmusson: "SAML 2.0; Designing Secure Identity Federation". Just one of many books on the topic.
Next Step:
SHRINE 4.0.0 Appendix A.1 - Installing the Software Stack
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</Sessions>
Configure error page and support email
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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
Within the <ApplicationDefaults><Sessions> element
- entityID is the URL of the idP to use for authentication
- We talk only SAML2 protocol
<SSO entityID="http://sso.med.harvard.edu/adfs/services/trust">
SAML2
</SSO>
Set logout to only local:
<Logout>Local</Logout>
Set status URL to
https://shrine-sso-node01.catalyst.harvard.edu/Shibboleth.sso/Status
And session URL to:
https://shrine-sso-node01.catalyst.harvard.edu/Shibboleth.sso/Session
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">
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Tomcat Configuration
Tomcat should accept requests on port 8080 only from localhost:
<Connector port="8080" protocol="HTTP/1.1"
connectionTimeout="20000"
redirectPort="6443" />
Some help might come from
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- Set up a listener on port 8080
- Accessing data received from the idP (Request Headers)
shibboleth2.xml
attribute-map.xml
sp.conf
Serving Metadata
Certificate
Developer tools
- SAML
Appendix: a Decent Book
Overview
Content Tools