2008/3/31, for.register for.register fregister@gmail.com:
I am a new user of mediawiki, my wiki is a private wiki, only authentic user is allowed. My question is how to set the homepage directly to login window.
Have you tried putting '#REDIRECT [[Special:Userlogin]]' on your main page? Alternatively, you could probably also edit MediaWiki:Mainpage and put 'Special:Userlogin' in there.
I haven't tried either method, though.