Configuring single sign-on

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

Before you begin

SSO is supported only when Lightweight Third Party Authentication (LTPA) is the authentication mechanism.

SSO is supported when Lightweight Third Party Authentication (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 WebSphere Application Server 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 WebSphere Application Servers, you must 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, 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.

The realm name is the same as the host name.

For the Lightweight Directory Access Protocol (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.

Because single sign-on is a subset of LTPA, it is recommended that you read Lightweight Third Party Authentication for more information.

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 that are 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.

Note: 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 WebSphere Application Server. This token contains the authentication identity attribute only.

Note: LtpaToken is generated for releases prior to WebSphere Application Server Version 5.1.0.2. LtpaToken2 is generated for WebSphere Application Server Version 5.1.0.2 and beyond.

Note: LtpaToken is generated for releases prior to WebSphere Application Server Version 5.1.1. LtpaToken2 is generated for WebSphere Application Server Version 5.1.1 and beyond.

Table 1. LTPA token types . This table describes the LTPA token types.

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 WebSphere Application Server Version 6.02. 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 administrative console. To access this panel, complete the following steps: Click Security > Global security. Under Web security, click Single sign-on (SSO).
LtpaToken and LtpaToken2	Use to interoperate with releases prior to WebSphere Application Server Version 5.1.1. 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 administrative console. To access this panel, complete the following steps: Click Security > Global security. Under Web security, click Single sign-on (SSO).

1. Open the administrative console.

   Type http://localhost:port_number/ibm/console to access the administrative console in a web browser.

   Type http://server_name:port_number/ibm/console to access the administrative console in a web browser.

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

2. Click Security > Global security.
3. Under Web security, click Single sign-on (SSO).
4. Click the Enabled option if SSO is disabled.
   After you click the Enabled option, make sure that you complete the remaining steps to enable security.
5. Click Requires SSL if all of the requests are expected to use HTTPS.
6. Enter the fully qualified domain names in the Domain name field where SSO is effective.
   If you specify domain names, they must be fully qualified. If the domain name is not fully qualified, WebSphere Application Server does not set a domain name value for the LtpaToken cookie and SSO is valid only for the server that created the cookie.

   When you specify multiple domains, you can use the following delimiters: a semicolon (;), a space ( ), a comma (,), or a pipe (|). WebSphere Application Server 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 WebSphere Application Server does not set a domain for the LtpaToken cookie.

   Table 2. Values to configure the Domain name field .

   This table describes the values to configure the Domain name field.

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

   If you specify the UseDomainFromURL, WebSphere Application Server 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, WebSphere Application Server 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.

   For more information, see Single sign-on settings.

7. Optional: Enable the Interoperability mode option if you want to support SSO connections in WebSphere Application Server 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 Version 6.1 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.

8. 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. For more information, see Security attribute propagation.

   Important: 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 token using WSSecurityHelper application programming interfaces (APIs).

   If you 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 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 this property is set to 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.

9. Click OK.