Multi Domain's Single Sign-on question.

Hi guys,

First time post on this forum so please bear with me… I’m having a bit of trouble setting up Single Sign-on feature to work across multiple domains. Not sure if it is a problem with the plugin or with my understanding of what it suppose to do so let me talk you through my set up, what I expect to happen and what actually happens… and hopefully someone will point out where I’m going wrong.


WP 3.3 Multi-site, Akismet, Multi-Domain v1.1.5, Domain Mapping v3.0.5, Multi-DB v3.1.2, Pro-sites v3.0.4

I imagine I’ve got a fairly typical setup: I’m running a single install of WP Multi-site with a number of CentralNIC domains pointing to its root (/). Multi-site is configured for subdirectory install of child blogs, primary blog is served out of the domains root. The idea is to split a number of user sites across multiple channels, which are defined by the parent domain. In other words:

My Parent Domains are:,

My user sites are:,,


Correct me if I’m wrong (and can quite easily be wrong here), but in my understanding Single Sign-on means that a user should be able to login into Site2 and be able to do all of the following:

(1) administer their own site as and when required

(2) visit a site on the same parent network (Site3) and leave a comment as themselves

(3) visit a site on a different parent network (Site1) and leave a comment as themselves

In both (2) and (3) the user should not be queried to login a second time, and in all cases their admin bar (a fixed bar at the top of the browser window spanning the entire width of the page) should remain visible.


Unfortunately the behaviour I’m experiencing is a little different from what I was expecting: when I login to my development instance as Site2 I indeed can admin; when I go to I can indeed leave a comment as Site2 and the admin bar remains visible.

However, when I go to the admin bar disappears and user Site2 (me) appears to be no longer logged in. When I return to either Site2 or Site3, the admin bar reappears and user Site2 once again appears to be logged in.

To me such behaviour appears to be a symptom of cookies not syncing across multiple domains. I’ve tried the same test on multiple browsers (Chrome, Safari) and two OS (MacOS X, Linux) and this behaviour is consistent across all of them.

So, to eliminate the possibility that it is the result of a conflict with another plugin, I’ve simplified my install to WP 3.3 Multi-site, Akismet, Multi-Domain v1.1.5, Multi-DB v3.1.2, ie: I’ve uninstalling Pro-sites and Domain Mapping plugins (wp-content/sunrise.php downgraded from multi-domains/dm_sunrise.php to multi-domains/sunrise.php). This resulted in no change to the behaviour I’m experiencing.

I was hoping somebody here could point out what else I could try before uninstalling everything and starting from scratch. Any idea or suggestions are welcome!!

PS: Not sure if it is relevant or not but my wp-content/db-config.php is void of any calls to add_global_table() as per