Connectors Content repository

below are the default Connectors found in SharePoint.

Bcs - Business Connectivity Services (internal protocol)
Bcs2 - Business Connectivity Services URLs (internal protocol)
File - File shares
http - Web sites
https - Web sites over Secure Sockets Layer (SSL)
Notes - Lotus Notes databases
Rb - Exchange public folders for versions prior to Microsoft Exchange Server 2003
Rbs - Exchange public folders over SSL for versions prior to Exchange Server 2003
Sps - People profiles in Microsoft Office SharePoint Portal Server 2003
Sps3 - People profiles in Microsoft Office SharePoint Server 2007
Sps3s - People profiles in Office SharePoint Server 2007 over SSL
Spss - People profiles in SharePoint Portal Server 2003 over SSL
Sts3 - Windows SharePoint Services 3.0 and Office SharePoint Server 2007 sites
Sts3s - Windows SharePoint Services 3.0 and Office SharePoint Server 2007 sites over SSL
Sts4 - Microsoft SharePoint Foundation 2010, SharePoint Server 2010, SharePoint Foundation 2013, SharePoint Server 2013, and SharePoint Server 2016 sites
Sts4s - SharePoint Foundation 2010, SharePoint Server 2010, SharePoint Foundation 2013, SharePoint Server 2013, and SharePoint Server 2016 sites over SSL.