Nginx maintenance page/redirect with ip exception

Coming fra Apache/htaccess, im trying to get my head around the Nginx paradigme. Im trying to achieve a temporary redirect to a www.mysite.com/maintenance.html page, for all visitors to www.mysite.com except visitors coming from IP:xx.xx.xx.xx.wich should have fuul access to the site.

I know how to achieve this with htaccess, but this doesnt applya to Nginx. I have tried different suggestions on modding nginx.conf, default.conf and mysite.cong file. I using virtual host and my site conf is placed in: /etc/nginx/sites-available/

Any simple solution to redirect all visitors except visitors defined by IP?