[support] Differenciating dev and prod site

Dear all,

I'm administrating a site for which I run several development version: one private on my laptop, just for me, one also on the same machine as the production version, for public testing...

I'm wondering whether you guys know a way to show something on the pages that make it clear that one is browsing a dev version rather than the production site. The algorithm could be something like this: if ip=PROD_IP and vhost=PROD_VHOST then production site else dev site

So the feature should require no database change, so that the different versions of the site can be differenciated from each other even after a database synchronisation. Any suggestion warmly appreciated. Thanks, Sebastien.