Blocking IP Addresses by Country of origin is a time consuming task. If you use a cisco or checkpoint firewall or even PF firewall on your linux distribution the configuration of such a large list of IP addresses to Block is a fairly large task.
But if you’re up to the task head over to http://www.countryipblocks.net/tag/cidr/
Here you can list all IP addresses by Country and then add them to a blacklist of untrusted IP Addresses.
Or better yet allow those you trust and disallow everyone else.
Now you can block bad IP addresses based on Country but user beware, IP addresses are added often, you’ll want to keep it up-to-date at least once a month.