We run a nonprofit online rol playing game that's being attacked with botnets (UDP flood). These botnet's zombies are distributed all over the world, mainly from Europe, Asia and the USA, and since 99.9% of the users in our game are players from within our country(Argentina) we were wondering how viable is to permanently block all packets coming from foreign IP addresses in order to mitigate the effects of these attacks. (Very few zombie's IPs were found to be Argentinean when checking the logs at the time of the attacks so having only them flooding the server will cause no harm).
Of course, we already discussed this with the company that hosts our server but they said they aren't able to "filter" packets that way (and didn't know much about it either). The thing is, they're a small, precarious company devoted mainly to small webpages hosting (is all we can afford).
When asking here "how viable" this option is, we just want to know if you think it's worth to keep looking for a company/datacenter that actually offers this "service"(because it's common practice or it's possible technically speaking or whatever the reason you think so), or we just need to forget about it and look for solutions somewhere else.
Needless to say, we can't afford large, expensive hosting companies equiped with DDoS mitigation devices at their datacenters.
Thanks in advance for your help.