Is it possible to accomplish the following scenario with a proxy server? We are having one internet facing server that we want to put behind a proxy for some reasons. We want everything to work as before. When they do a request all connections will be forward to the internal server which will send back the information through the proxy. We want to be able to change to proxy to show an maintenance page whenever we are doing maintenance and change it back to forwarding traffic when we are done. We do also want to be able to keep forwarding all users that are using the sites but show an maintenance page for all new users for a time before showing the maintenance page for everyone in order to give the users some time to finish their work before kicking them out.
You can accomplish this with nginx if you just want to proxy requests to your internal server (using
proxy_pass on nginx), nginx is available at http://nginx.org
If you wish you would also have some cacheing on top of those rules you with to accomplish have a look at Varnish (available at http://www.varnish-cache.org/).
Both will give you exactly what you want, nginx won't cache your requests but varnish will do, it just depends on what you wish to acomplish.