rewrite url in nginx

[ezak]

I have a lot of links is indexed to google and it doesn't indexed on my site
similar that links

http://www.site.com/vb/?71-DCT-4-WD-2/page7=
http://www.site.com/vb/?360-SPT-Box/page14=
http://www.site.com/vb/?71-DCT-4-WD-2/page44=

this links is about 2000 links and its show my home page and I need to rewrite all this url to my home page

I don't use any SEO links, just use default vbulletin links

i want to rewrite any links started with this in nginx
http://www.site.com/vb/?(.*) to the default home page http://www.site.com/vb/forum.php

I tried a lot but no success like this
rewrite ^/vb/\?(.*)$ /vb/forum.php permanent;
but its make too many rewrite

how to make that, and thanks in advice