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Implement single sign-on to minimize web user authentications

With single sign-on (SSO) support, web users can authenticate once when accessing web resources across multiple WebSphere Application Server. Form login mechanisms for web applications require that SSO is enabled. Use this topic to configure single sign-on for the first time.

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 domain name service (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 WAS, 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 the LDAP the realm name is the host:port realm name of the LDAP server. The LTPA authentication mechanism requires that we enable SSO if any of the web applications have form login as the authentication method.

Because single sign-on is a subset of LTPA, IBM recommends reading LTPA for more information.

When we enable security attribute propagation, the following cookie is always added to the response:

Token type Purpose How to specify
LtpaToken2 only This is the default token type. It uses the AES-CBC-PKCS5 padding encryption strength (128-bit key size). This token is stronger than the older LtpaToken used prior to WAS v6.02. IBM recommends this option when interoperability with older releases is not necessary. Disable the Interoperability mode option in the SSO configuration panel within the administrative console. To access this panel:

  1. Click Security > Global security.

  2. Under Web security, click Single sign-on (SSO).

LtpaToken and LtpaToken2 Use to interoperate with releases prior to WAS v5.1.1. The older LtpaToken cookie is present along with the new LtpaToken2 cookie. Provided the LTPA keys are correctly shared, we should be able to interoperate with any version of WebSphere using this option. Enable the Interoperability mode option in the SSO configuration panel within the administrative console. To access this panel:

  1. Click Security > Global security.

  2. Under Web security, click Single sign-on (SSO).

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


Tasks

  1. Open the administrative console.

      http://fully_qualified_host_name:port_number/ibm/console

      (iSeries) http://server:port_number/ibm/console

    Port 9060 is the default port number for accessing the administrative console. During installation, however, we might have specified a different port number. Use the appropriate port number.

  2. Click...

      Security > Global security > Web security > Single sign-on (SSO)

  3. Click the Enabled option if SSO is disabled. After clicking the Enabled option, make sure that completing the remaining steps to enable security.

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

  5. Enter the fully qualified domain names in the Domain name field where SSO is effective. If we 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.

    When we specify multiple domains, we can 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 we specify ibm.com ; austin.ibm.com and a match is found in the ibm.com domain first, WAS 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.

    Domain name value type Example Purpose
    Blank
    		The domain is not set. This causes the browser to set the domain to the request host name. The sign-on is valid on that single host only.
    Single domain name austin.ibm.com If the request is to a host within the configured domain, the sign-on is valid for all hosts within that domain. Otherwise, it is valid on the request host name only.
    UseDomainFromURL UseDomainFromURL If the request is to a host within the configured domain, the sign-on is valid for all hosts within that domain. Otherwise, it is valid on the request host name only.
    Multiple domain names austin.ibm.com;raleigh.ibm.com The sign-on is valid for all hosts within the domain of the request host name.

    Cross-domain SSO is not supported. For example, chicago.xxx.com and cleveland.yyy.com where the DNS domains are different.

    Multiple domain names and UseDomainFromURL austin.ibm.com;raleigh.ibm.com; UseDomainFromURL The sign-on is valid for all hosts within the domain of the request host name.

    Cross-domain SSO is not supported. For example, chicago.xxx.com and cleveland.yyy.com where the DNS domains are different.

    If we 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. We can type usedomainfromurl to use this value.

    See Single sign-on settings.

  6. Optional: Enable the Interoperability mode option to support 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 token into the response so it can be sent to other servers that work only with this token type. Otherwise, only the LtpaToken2 token is added to the response.

    If performance is a consideration, and we are only connecting to v6.1 or later servers and are not running products that depend on the LtpaToken, do not enable Interoperability mode. When Interoperability mode is not enabled, an LtpaToken is not returned in a response.

  7. Optional: Enable the Web inbound security attribute propagation option if we 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. See Security attribute propagation.

    If the following statements are true, IBM recommends disabling the Web inbound security attribute propagation option for performance reasons:

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

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

    If we find that we 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.

    The following two custom properties might help to improve performance when security attribute propagation is enabled:

    • com.ibm.CSI.propagateFirstCallerOnly

      Default is true. When this custom property is set to true the first caller in the propagation token that stays on the thread is logged when security attribute propagation is enabled. When false, all of the caller switches are logged, which can affect performance.

    • com.ibm.CSI.disablePropagationCallerList

      When this custom property is set to true the ability to add a caller or host list in the propagation token is completely disabled. This function is beneficial when the caller or host list in the propagation token is not needed in the environment.

  8. Click OK.


What to do next

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


Subtopics


Related:

  • Web component security
  • LTPA
  • Security attribute propagation
  • Authenticating users
  • Enable security
  • Configure the LTPA mechanism
  • Single sign-on configuration troubleshooting tips for security
  • Security: Resources for learning