I already implemented single sign on (SSO) for sub-domain on same and different server.
Using the following technique:
session_name('example');
session_set_cookie_params(0, '/', '.example.com');
session_start();
d1.example.com on SERVER1
d2.example.com on SERVER1
d3.example.com on SERVER2
and this successfully works.
To create session for sub-domain d3.example.com on SERVER2 i use a curl to invoke a page on that server
But now i added another domain www.different.com to SERVER2, all data, users, services, code are shared from example.com, but its not a subdomain.
I tries same login technique of cURL for this new domain(www.different.com), but failed to login to www.different.com. although user is shown logged-in on all other sites.
Because www.different.com is not a subdomain of example.com, so cookie(i.e. session_set_cookie_params(0, '/', '.example.com'); ) is not written for this site.
I want to know if there any solution that need minimum changes, because there are 18 subdomains working on above scenario. and changing all these is very tedious.