| Siebel Portal Framework Guide > Integrating External Content > Understanding Portal Agents > Portal Agents and Authentication Strategies
 Portal Agents can be configured to support different authentication strategies: 
Simple Portal Agents. External application does not require any authentication parameters.
Single Sign-On Portal Agents. External application requires authentication parameters.
NCSA-based Portal Agents send a user name and password as part of the URL in plain text. Note that NCSA is no longer widely used as an authentication mechanism.
Form-based Portal Agents send authentication parameters as part of the body portion of the HTTP request.
 For more information about authentication, see Security Guide for Siebel Business Applications. |