Single Sign On is a concept of signing to the application once and can view any web sites within same domain (eg. Dotnetfunda.com).
In SSO you need to have two servers, one have the web server and in other the policy server(SSO).
You can maintain any database like LDAP, Oracle, SQL Server database to store the user information. Most preferred is LDAP for the SSO.
There are different software available in market which helps in integrating Single Sign On.
The following are the products which are mainly used in banking, shopping carts, manufacturing secors.
Computer Associates Siteminder
Here the persistent cookies maintains when you switch to different web sites in the same browser window. In few occurrence, when you open a new browser window it will ask for credentials when you visit a web site.
How it Works
When the user attempts to view a web site, if the page is protected page, then it requires authentication to view the page. If the page is not a protected page, then it won't ask you for authentication.
Here web server act as Mediator, which carries the details to and from policy server.
Once the user details are authenticated in policy server, then user is allowed to view the protected page otherwise again it will ask to prompts for correct credentials.
Here the persistent cookie is stored in the client browser and helps in viewing different web sites.
User Browser -> Web Server - > Policy Server - > Database
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