Configure single signon

 

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Before you begin

With single signon (SSO) support, Web users can authenticate once when accessing Web resources across multiple application servers. Form login mechanisms for Web applications require that SSO is enabled.

SSO is supported only when LTPA is the authentication mechanism.

When SSO is enabled, a cookie is created containing the LTPA token and inserted into the HTTP response. When the user accesses other Web resources in any other WAS process in the same DNS domain, the cookie is sent in the request. The LTPA token is then extracted from the cookie and validated. If the request is between different cells of application servers, share the LTPA keys and the user registry between the cells for SSO to work. The realm names on each system in the SSO domain are case sensitive and must match identically.

For local OS on the Windows platform, the realm name is the domain name if a domain is in use or the machine name.

On the Linux or UNIX platforms, the release name is the same as the host name.

For LDAP the realm name is the host:port realm name of the LDAP server. The LTPA authentication mechanism requires that you enable SSO if any of the Web applications have form login as the authentication method.

When you enable security attribute propagation, the following cookies are added to the response:

LtpaToken

The LtpaToken is used for interoperating with previous releases of WAS. This token contains the authentication identity attribute only.

LtpaToken2

LtpaToken2 contains stronger encryption and enables you to add multiple attributes to the token. This token contains the authentication identity and additional information such as the attributes used for contacting the original login server and the unique cache key for looking up the Subject when considering more than just the identity in determining uniqueness.

Token type Purpose How to specify
LtpaToken only Used for the same SSO behavior existing in WAS V5.1 and previous releases. Interoperable with those previous releases. Disable Web inbound security attribute propagation by going to...

Security | Global security | Authentication mechanisms | LTPA | Single signon (SSO)
LtpaToken2 only Used for Web inbound security attribute propagation and uses the AES, CBC, PKCS5 padding encryption strength (128 bit key size). However, this token type is not interoperable with releases prior to WAS V5.1.1. The token type allows for multiple attributes specified in the token (mostly containing information to contact the original login server). Enable the Web inbound security attribute propagation option in the SSO configuration panel within the administrative console. Disable the Interoperability mode option in the SSO configuration panel within the administrative console.
LtpaToken and LtpaToken2 Support both of the previous two options. The token types are interoperable with releases prior to WAS V5.1.1 because LtpaToken is present. The security attribute propagation function is enabled because the LtpaToken2 is present. Enable the Web inbound security attribute propagation option in the SSO configuration panel within the administrative console. Enable the Interoperability mode option in the SSO configuration panel within the administrative console.

 

Overview

The following steps are required to configure SSO for the first time.

 

Procedure

  1. From the admin console, go to...

    Security | Global security | Authentication mechanisms | LTPA | Single signon (SSO)

  2. Click the Enabled option if SSO is disabled. After you click Enabled, make sure that you complete the remaining steps to enable security.

  3. Click the Requires SSL option if all of the requests are expected to use HTTPS.

  4. Enter the fully-qualified domain names in the Domain name field where SSO is effective. The cookie is sent for all of the servers that are contained within the domains that you specify in this field. If you specify domain names, they must be fully qualified. If the domain name is not fully qualified, WAS does not set a domain name value for the LtpaToken cookie and SSO is valid only for the server that created the cookie.

    One can configure the Domain name field using any of the following values:

    Domain name value type Example
    Blank  
    Single domain name austin.ibm.com
    UseDomainFromURL UseDomainFromURL
    Multiple domain names austin.ibm.com;raleigh.ibm.com
    Multiple domain names and UseDomainFromURL

    • austin.ibm.com;raleigh.ibm.com
    • UseDomainFromURL

    If you specify the UseDomainFromURL, WAS sets the SSO domain name value to the domain of the host that makes the request. For example, if an HTTP request comes from server1.raleigh.ibm.com, WAS sets the SSO domain name value to raleigh.ibm.com.

    Tip: The value, UseDomainFromURL, is case insensitive. You can type usedomainfromurl to use this value.

    When you specify multiple domains, use the following delimiters: a semicolon (;), a space ( ), a comma (,), or a pipe (|). WAS searches the specified domains in order from left to right. Each domain is compared with the host name of the HTTP request until the first match is located. For example, if you specify ibm.com; austin.ibm.com and a match is found in the ibm.com domain first, WebSphere Application server does not continue to search for a match in the austin.ibm.com domain. However, if a match is not found in either the ibm.com or austin.ibm.com domains, then WAS does not set a domain for the LtpaToken cookie.

  5. Optional: Enable the Interoperability mode option if you want to allow SSO connections in WAS version 5.1.1 or later to interoperate with previous versions of the application server. This option sets the old-style LtpaToken into the response so it can be sent to other servers that work only with this token type. However, this option applies only when the Web inbound security attribute propagation option is enabled. In this case, both the LtpaToken and LtpaToken2 are added to the response. Otherwise, only the LtpaToken2 is added to the response. If the Web inbound security attribute propagation option is disabled, then only the LtpaToken is added to the response.

  6. Optional: Enable the Web inbound security attribute propagation option if you want information added during the login at a specific front-end server to propagate to other front-end servers. The SSO token does not contain any sensitive attributes, but does understand where the original login server exists in cases where it needs to contact that server to retrieve serialized information. It also contains the cache look up value for finding the serialized information in DynaCache, if both front-end servers are configured in the same DRS replication domain.

    If the following statements are true, it is recommended that you disable the Web inbound security attribute propagation option for performance reasons:

    • You do not have any specific information added to the Subject during a login that cannot be obtained at a different front-end server.

    • You did not add custom attributes to the PropagationToken using WSSecurityHelper APIs.

    If you find you are missing custom information in the Subject, re-enable the Web inbound security attribute propagation option to see if the information is propagated successfully to other front-end application servers. If you disable SSO, but use a trust association interceptor instead, you might still need to enable the Web inbound security attribute propagation option if you want to retrieve the same Subject generated at different front-end servers.

  7. Click OK.

 

What to do next

For the changes to take effect, save, stop, and restart all the product servers (deployment managers, nodes and Application Servers).

 

See also

Single signon settings
Troubleshoot single signon configurations
Web component security
Lightweight Third Party Authentication
Security attribute propagation
Configure Lightweight Third Party Authentication
Security: Resources for learning

 



 

 

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IBM is a trademark of the IBM Corporation in the United States, other countries, or both.