Using Squid-Cache with Azureus.
If you use Squid-Cache proxy server to cache all your http request, it's possible that the IP address seen by the tracker is the address of your internal network. This happens because the tracker may read the value of HTTPXFORWARDED_FOR variable from the request.
You have to add the following directive "forwarded_for off" to your squid.conf file. This change will force request to send on the variable "unknown, xxx.yyy.zzz.www", where xxx.yyy.zzz.www is the public ip of your internet connection.