Page History
This appendix is designed to guide system admins installing Single-Sign-On (SSO) for Shrine (using Shibboleth).
Very Basic Overview of SSO
IdP (Identity Provider): A web-based system that can authenticate a user on behalf of another system called a SP (for Service Provider).
Overview: How it Works
Installation Layout
Apache Configuration
/etc/httpd/conf.d/sp.conf
Here is the entire content of the Apache configuration for using Shibboleth
ServerName should be set
ServerName shrine-sso-node01.catalyst.harvard.edu
Timeout 300
ProxyTimeout 300
Set up proxy to Tomcat for URLs that start with shrine-api
ProxyIOBufferSize 65536
#### serve content from Tomcat
ProxyPassReverse "/shrine-api/" "http://127.0.0.1:8080/shrine-api/"
ProxyPass "/shrine-api/" "http://127.0.0.1:8080/shrine-api/"
Serve metadata dynamically but as though an XML file was being accessed, from Tomcat
#### serve metadata
ProxyPass "/sp-metadata.xml" "http://127.0.0.1:8080/shrine-api/sso/rest/util/sp-metadata"
...
In this implementation of SSO, the SP consists of the Shibboleth SP version 3 software. See
https://shibboleth.atlassian.net/wiki/spaces/SP3/
...
# "You do not have to set UseCanonicalName On, but you usually should ..."
UseCanonicalName On
The following tells Apache to use Shibboleth for authentication of any URL starting with "shrine-api":
#### whitelist URLs which need to be protected by Shibboleth
<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. However the recommended (and default) setup (ShibUseEnvironment=On and ShibUseHeaders=Off) requires proxying to Tomcat using the AJP protocol, which we are not using (we are proxying using the HTTP protocol).
# as per https://shibboleth.atlassian.net/wiki/spaces/SHIB2/pages/2577072327/NativeSPApacheConfig,
# ShibUseEnvironment is strongly favored over ShibUseHeaders
ShibUseEnvironment Off
ShibUseHeaders On
</LocationMatch>
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 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
https://shibboleth.atlassian.net/wiki/spaces/SP3/pages/2065335529/GettingStarted
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
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
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
Near the top of the file in the ApplicationDefaults element, we set
- 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)
- 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"
sessionHook="/shrine-api/sso/rest/authentication/consume"
signing="true"
>
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
Tomcat Configuration
- 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