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Code Block
(Windows) C:\opt\shibboleth-idp> bin\module.bat -t idp.authn.External \|\| bin\module.bat -e idp.authn.External (Other) $ bin/module.sh -t idp.authn.External \|\| bin/module.sh -e idp.authn.External

General Configuration

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title	V4.0

Use conf/authn/external-authn-config.xml to configure this flow.

The shibboleth.authn.External.externalAuthnPath bean defines the flow redirection path to the resource that's used to perform the external login, by default a context-relative location. It can be modified if needed, but must be a resource with access to the container session. Modify as needed to match the location of your external interface (see the documentation on flow redirects).

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title	V4.1+

Most of the usual options are available via authn/authn.properties, and some more advanced cases will require defining/adjusting bean definitions in authn/external-authn-config.xml.

The idp.authn.External.externalAuthnPath property defines the flow redirection path to the resource that's used to perform the external login, by default a context-relative location. It can be modified if needed, but must be a resource with access to the container session. Modify as needed to match the location of your external interface (see the documentation on flow redirects).

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Call ExternalAuthentication.startExternalAuthentication(HttpServletRequest), saving off the result as a key.
Do work as necessary (reading request details from the attributes below). Any redirects must preserve the key value returned in step 1 because it must be used to complete the login later.
Set request attributes to communicate the result of the login back.
Call ExternalAuthentication.finishExternalAuthentication(String, HttpServletRequest, HttpServletResponse). The first parameter is the key returned in step 1.

A Example JSP implementation is below. It works as is, but is obviously quite limited.implementations are below.

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title	External interface example in JSP

Code Block

language	java

<%@ page pageEncoding="UTF-8" %>
<%@ page import="net.shibboleth.idp.authn.ExternalAuthentication" %>
<%@ page import="net.shibboleth.idp.authn.ExternalAuthenticationException" %>

<%
try {
    final String key = ExternalAuthentication.startExternalAuthentication(request);
    final String username = request.getRemoteUser();
    if (username != null) {
        request.setAttribute(ExternalAuthentication.PRINCIPAL_NAME_KEY, username);
    }
    ExternalAuthentication.finishExternalAuthentication(key, request, response);
     
} catch (final ExternalAuthenticationException e) {
    throw new ServletException("Error processing external authentication request", e);
}
%>

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title	External interface with attributes in JSP

Code Block

language	java

<%@ page pageEncoding="UTF-8" %>
<%@ page import="net.shibboleth.idp.authn.*" %>
<%@ page import="net.shibboleth.idp.attribute.*"%>
<%@ page import="net.shibboleth.idp.authn.principal.*"%>
<%@ page import="java.util.*"%>

<%
try {
    final String key = ExternalAuthentication.startExternalAuthentication(request);

    HashSet<Principal> principals=new HashSet<Principal>();

    principals.add(new UsernamePrincipal("bbarker"));

    //<DataConnector xsi:type="Subject" exportAttributes="mail eduPersonNickname" id="myId" />
    //<AttributeDefinition ... <InputDataConnector ref="myId" ...
    IdPAttribute attr=new IdPAttribute("eduPersonNickname");
    attr.setValues(Collections.singleton(new StringAttributeValue("Bob Barker")));
    principals.add(new IdPAttributePrincipal(attr));

    attr=new IdPAttribute("mail");
    attr.setValues(Collections.singleton(new StringAttributeValue("bbarker@example.org")));
    principals.add(new IdPAttributePrincipal(attr));

    request.setAttribute(ExternalAuthentication.SUBJECT_KEY,new Subject(false, principals, Collections.EMPTY_SET, Collections.EMPTY_SET));

    ExternalAuthentication.finishExternalAuthentication(key, request, response);

} catch (final ExternalAuthenticationException e) {
    throw new ServletException("Error processing external authentication request", e);
}
%>

Inputs

On first access to the external resource, the request attributes below will be set.

Name	Type	Function
opensamlProfileRequestContext	ProfileRequestContext	Access to full request context tree
forceAuthn	Boolean	Whether the requester asked for re-authentication
isPassive	Boolean	Whether the requested asked for passive authentication
relyingParty	String	Name of the relying party requesting authentication
extended	Boolean	Whether this login flow has been invoked as an extension of another login flow

Outputs

Name	Type	Function
principalName	String	Name of authenticated subject to use as the login result
principal	Principal	Java Principal object to use as the login result
subject	Subject	Java Subject object to use as the login result
authnError	String	Error message to return in place of a successful login
authnException	Exception	Explicit exception object to return in place of a successful login
authnInstant	Instant	Exact time of authentication to report back
authnAuthorities	Collection<String>	Ordered collection of URIs identifying upstream/proxied authenticating "authorities" used to authenticate the subject
attributes	Collection<IdPAttribute>	Collection of IdPAttribute objects to associate with the authenticated subject
doNotCache	Boolean	If true, prevents the result from being saved for future use for SSO
previousResult	Boolean	If true, the "new" AuthenticationResult is created with the "previousResult" flag set to true (mainly impacts auditing)

Only one "result" or error attribute should be set by the external code. Setting more than one has unspecified behavior. In most cases, the simple principalName should be returned on success, but you can return the more complex objects to pass back additional information such as public or private credentials or custom principal data.

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Note that returning a Subject is often paired with setting the shibboleth.authn.External.addDefaultPrincipals bean (V4.0) or idp.authn.External.addDefaultPrincipals property (V4.1+) to false, to dynamically establish Principal(s) representing the authentication method used without having them overwritten. For example, your External flow's supportedPrincipals property might be defined to include both password and multi-factor authentication Principals (meaning it supports both methods), but you can return the specific method used at runtime in the Subject.

Reference

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title	Beans (V4.0)

The beans defined, or expected to be defined, in authn/external-authn-config.xml follow:

Bean ID / Type	Default	Description
shibboleth.authn.External.externalAuthnPath String	contextRelative:external.jsp	Spring Web Flow redirection expression for the protected resource
shibboleth.authn.External.externalAuthnPathStrategy Function<ProfileRequestContext,String>		Optional function that returns the redirection expression to use for the protected resource
shibboleth.authn.External.ClassifiedMessageMap Map<String,List<String>>	(see file)	A map between defined error/warning conditions and events and implementation-specific message fragments to map to them.
shibboleth.authn.External.resultCachingPredicate Predicate<ProfileRequestContext>		Optional bean that can be defined to control whether to preserve the authentication result in an IdP session
shibboleth.authn.External.addDefaultPrincipals Boolean	true	Whether to add the content of the `supportedPrincipals` property of the underlying flow descriptor to the resulting Subject
shibboleth.authn.External.matchExpression Pattern		Regular expression to match username against

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title	Beans (V4.1+)

The beans defined, or expected to be defined, in authn/external-authn-config.xml follow:

Bean ID / Type

Default

Description

shibboleth.authn.External.externalAuthnPathStrategy

Function<ProfileRequestContext,String>

Optional function that returns the redirection expression to use for the protected resource

shibboleth.authn.External.ClassifiedMessageMap

Map<String,List<String>>

(see file)

A map between defined error/warning conditions and events and implementation-specific message fragments to map to them.

shibboleth.authn.External.resultCachingPredicate

Predicate<ProfileRequestContext>

Optional bean that can be defined to control whether to preserve the authentication result in an IdP session

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title	Properties (V4.1+)

The flow-specific properties usable via authn/authn.properties are:

Name	Default	Description
idp.authn.External.externalAuthnPath	contextRelative:external.jsp	Spring Web Flow redirection expression for the protected resource
idp.authn.External.matchExpression		Regular expression to match username against

The general properties configuring this flow via authn/authn.properties are:

Name	Default	Description
idp.authn.External.order	1000	Flow priority relative to other enabled login flows (lower is "higher" in priority)
idp.authn.External.nonBrowserSupported	false	Whether the flow should handle non-browser request profiles (e.g., ECP)
idp.authn.External.passiveAuthenticationSupported	false	Whether the flow allows for passive authentication
idp.authn.External.forcedAuthenticationSupported	false	Whether the flow supports forced authentication
idp.authn.External.proxyRestrictionsEnforced	%{idp.authn.enforceProxyRestrictions:true}	Whether the flow enforces upstream IdP-imposed restrictions on proxying
idp.authn.External.proxyScopingEnforced	false	Whether the flow considers itself to be proxying, and therefore enforces SP-signaled restrictions on proxying
idp.authn.External.discoveryRequired	false	Whether to invoke IdP-discovery prior to running flow
idp.authn.External.lifetime	%{idp.authn.defaultLifetime:PT1H}	Lifetime of results produced by this flow
idp.authn.External.inactivityTimeout	%{idp.authn.defaultTimeout:PT30M}	Inactivity timeout of results produced by this flow
idp.authn.External.reuseCondition	shibboleth.Conditions.TRUE	Bean ID of Predicate<ProfileRequestContext> controlling result reuse for SSO
idp.authn.External.activationCondition	shibboleth.Conditions.TRUE	Bean ID of Predicate<ProfileRequestContext> determining whether flow is usable for request
idp.authn.External.subjectDecorator		Bean ID of BiConsumer<ProfileRequestContext,Subject> for subject customization
idp.authn.External.supportedPrincipals	(see below)	Comma-delimited list of protocol-specific Principal strings associated with flow
idp.authn.External.addDefaultPrincipals	true	Whether to auto-attach the preceding set of Principal objects to each Subject produced by this flow

Most of the flows, including this one, default to describing themselves in terms of "password"-based authentication, so the supportedPrincipals property defaults to the following XML:

Code Block

language	xml

<list>
    <bean parent="shibboleth.SAML2AuthnContextClassRef"
        c:classRef="urn:oasis:names:tc:SAML:2.0:ac:classes:PasswordProtectedTransport" />
    <bean parent="shibboleth.SAML2AuthnContextClassRef"
        c:classRef="urn:oasis:names:tc:SAML:2.0:ac:classes:Password" />
    <bean parent="shibboleth.SAML1AuthenticationMethod"
        c:method="urn:oasis:names:tc:SAML:1.0:am:password" />
</list>

In property form, this is expressed as (note especially the trailing commas, which MUST be there):

Code Block

idp.authn.External.supportedPrincipals = \
    saml2/urn:oasis:names:tc:SAML:2.0:ac:classes:PasswordProtectedTransport, \
    saml2/urn:oasis:names:tc:SAML:2.0:ac:classes:Password, \
    saml1/urn:oasis:names:tc:SAML:1.0:am:password

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title	Flow Descriptor XML (V4.1+)

To replace the internally defined flow descriptor bean, the following XML is required:

Code Block

language	xml

<util:list id="shibboleth.AvailableAuthenticationFlows">
 
    <bean p:id="authn/External" parent="shibboleth.AuthenticationFlow"
            p:order="%{idp.authn.External.order:1000}"
            p:nonBrowserSupported="%{idp.authn.External.nonBrowserSupported:false}"
            p:passiveAuthenticationSupported="%{idp.authn.External.passiveAuthenticationSupported:false}"
            p:forcedAuthenticationSupported="%{idp.authn.External.forcedAuthenticationSupported:false}"
            p:proxyRestrictionsEnforced="%{idp.authn.External.proxyRestrictionsEnforced:%{idp.authn.enforceProxyRestrictions:true}}"
            p:proxyScopingEnforced="%{idp.authn.External.proxyScopingEnforced:false}"
            p:discoveryRequired="%{idp.authn.External.discoveryRequired:false}"
            p:lifetime="%{idp.authn.External.lifetime:%{idp.authn.defaultLifetime:PT1H}}"
            p:inactivityTimeout="%{idp.authn.External.inactivityTimeout:%{idp.authn.defaultTimeout:PT30M}}"
            p:reuseCondition-ref="#{'%{idp.authn.External.reuseCondition:shibboleth.Conditions.TRUE}'.trim()}"
            p:activationCondition-ref="#{'%{idp.authn.External.activationCondition:shibboleth.Conditions.TRUE}'.trim()}"
            p:subjectDecorator-ref="#{getObject('%{idp.authn.External.subjectDecorator:}'.trim())}">
        <property name="supportedPrincipalsByString">
            <bean parent="shibboleth.CommaDelimStringArray"
                c:_0="#{'%{idp.authn.External.supportedPrincipals:}'.trim()}" />
        </property>
    </bean>
 
</util:list>

In older versions and upgraded systems, this list is defined in conf/authn/general-authn.xml. In V4.1+, no default version of the list is provided and it may simply be placed in conf/global.xml if needed.

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Versions Compared

Old Version 24

New Version 25

Key

General Configuration

Inputs

Outputs

Reference