WAS v8.5 > Secure applications > Authenticate users

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 appservers. 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 WASs, 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.

The realm name is the same as the host name except for Windows local OS, where the realm name is the domain name if a domain is in use. If a domain is not used, the realm name is the machine name.

For the 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 cookie is always added to the response:

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.

The following cookie is optionally added to the response when the Interoperability mode flag is enabled:

LtpaToken LtpaToken is used for inter-operating with previous releases of WAS. This token contains the authentication identity attribute only.

LtpaToken is generated for releases prior to WAS v5.1.1. LtpaToken2 is generated for WAS v5.1.1 and beyond.

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. This is the recommended option when interoperability with older releases is not necessary. Disable the Interoperability mode option in the SSO configuration panel within the dmgr console. To access this panel...

    Security | Global security | Web security | 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, you 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 dmgr console. To access this panel...

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

To configure SSO for the first time, open.

    From the dmgr console, select...

      Security | Global security | Web security | Single sign-on (SSO) Enabled

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

  2. 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.
    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.

    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 .

    The value, UseDomainFromURL, is case insensitive. We can type usedomainfromurl to use this value.

    For more information, see Single sign-on settings.

  3. 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 you are only connecting to v6.1 or later servers that 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.

  4. 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. For more information, 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.
    • You did not add custom attributes to the PropagationToken token using WSSecurityHelper APIs.
    If we find that 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.

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

    • com.ibm.CSI.propagateFirstCallerOnly

      The default value of this property is true. When 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 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.

  5. Click OK.

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


Subtopics


Related concepts:

Web component security
LTPA
Security attribute propagation


Related


Authenticate users
Enable security
Configure the LTPA mechanism


Reference:

Single sign-on configuration troubleshooting tips for security
Security: Resources for learning


Related information:

Create a single sign-on for HTTP requests using SPNEGO Web authentication


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