In case that you experience lots of hash fails in your uTorrent client, or just simply want to filter out suspicious IP addresses, you should use an IP blocklist.
Here is how:
1. Download an appropriate IP blocklist. The file will be saved in .gz format, therefore you will have to unzip it. The result is a file called “ipfilter.dat”, that is the IP blocklist.
2. Copy/paste the ipfilter.dat file into your %appdata%\utorrent folder. This folder looks like “C:\Documents and Settings\<your Windows username>\Application Data\uTorrent”.
3. Start uTorrent, go into Options -> Preferences -> Advanced, set the ipfilter.enable option to True and hit Apply/OK.
If you have successfully executed the above steps, then on the Logger tab of uTorrent, you should see something like “Loaded ipfilter.dat (xxxx entries). If you see there “0 entries”, then something went wrong.
You can reload the list without restarting uTorrent, by simply setting the ipfilder.enable option to False/OK and then True/OK.
The same ipfilter.dat file can also be used in your eMule client.