Jeremy Pry

Force all of the users on your Multisite Network to login at the main site address.

Redirect Network Login

Redirect the the wp-login.php for sub-sites to the main site

asergeev34

Plugin of additional WordPress customization for creation of social network site.
Allows to implement:
1) placing of user login and logout tools in menu areas and widgets’ areas of 
 stand-alone sites of social network;
2) functioning of subscription tools for updates of stand-alone sites by 
 members of social network;
3) improving of management and site navigation tools (toolbar management, 
 page scrolling, page redirection).
It is oriented on work in WordPress Multisite mode with social networking plugin 
BuddyPress. It can be used in regular WordPress installations for solving individual 
tasks.

MIF WP Customizer

Plugin of additional WordPress customization for creation of social network site.

Redirect Network Login vs MIF WP Customizer