Whitelisting IP addresses for ratelimiting

[James Fidell]

I have my configuration set up based on the information at
http://gadelkareem.com/2012/03/25/limit-requests-per-ip-on-nginx-using-httplimitzonemodule-and-httplimitreqmodule-except-whitelist/
as follows:

http {
...
   geo $unlimited {
     default 1;
     192.168.45.56/32 0;
   }
...
   limit_req_zone  $binary_remote_addr  zone=unlimited:10m   rate=10r/m;
...
   server {
   ...
     location / {
       limit_req zone=unlimited burst=5;
     }
   }
}

I believe this should mean that requests from IP address 192.168.45.56
are not subject to the rate limiting, but it isn't working (they do get
blocked by the rate limiting) and I can't see why.

Is my configuration obviously wrong somewhere?

And if not, is there any way I can easily debug why the rate-limiting is
being applied?

Thanks,
James