Banning IP addresses based on Country Code

Greetings,
Just wondering if this is possible.  Can I somehow ban all IP addresses with a country code of China?

All my spam comes from China.  I click on the IP address and can see that the lookup of the address shows the country code of China.

Is there any mod, or new feature that would allow me to ban posts from China?

Thanks
Mark

Hi Bruce,
Thanks for the detailed reply.  I'm in China and proxy servers are banned, and the ways to change the IP address are limited.  You could be correct though, as the ip addressed in my spam may have been changed to indicate china....  when in fact its from somewhere else....

Thanks again for your reply.  I appreciate your efforts to keep the cost of the software so low.  It has been soooo helpful to people with student loan issues in Canada!

Mark