The registry edit to enable the connections tab in ie is

HKEY_CURRENT_USER\Software\Policies\Microsoft\Internet Explorer\ControlPanel

Change the ConnectionsTab DWORD value to 0 to enable, 1 to disable

Thanks to WindowsITPro.com for this help

for more detailed information check out - http://windowsitpro.com/article/articleid/37775/how-can-i-use-the-registry-to-restrict-access-to-the-microsoft-internet-explorer-ie-configuration-tabs.html