1.need to add Federated domain to the
site.
(configuration of Federated
Identity Management (FIM))
2.
need to add UPN suffixes to the Forest
3.
Create STS(security token service)
4. Enable and configure Active Directory
Federation Services (AD FS) 2.0
(https://technet.microsoft.com/en-us/library/adfs2(v=ws.10).aspx) for intranet
if we want external authentication process need to enable Active Directory
proxy.
5.
test the SSO(Single Sign On)
from (https://testconnectivity.microsoft.com/?testid=SingleSignOn)
6.
Then configure failures from SSO(Single Sign On) test
-->now you can login from portal page (portal.microsoftonline.com) by using AD user credentials.
--> if you want separate custom login page,you have go though from following steps.
7.
create SSL certificate clearance
8.
create the custom login page
9.
handle the input credentials from page by CSOM using STS and SSL with OAuth.
to enable sso we have to follow above step by step....