How to limit web site access to USA or North America only

This is a corporate site so Private. We want to limit access by IP address to USA/Canada or North America. Based on IP ra开发者_运维百科nge, would allow user/pwd to get in otherwise -'no access'. Just trying to limit hack exposure from anything overseas.

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Anybody who could get past your password security could easily get past any IP filtering security (and it may even be seen as a challenge, thus increasing the risk of overseas hacking). I think the premise of your question is flawed.

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If your main aim is to prevent unauthorized access to your website by IP... that will never ever work. Its so easy to bypass that. a user/pwd would be a more secure option.

To answer your question, if you have certain features or a complete website block that you want to do, this is a tutorial:

http://blog.newagesolution.net/2008/11/how-to-block-country-and-ip-addresses.html

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There are various libraries that will do geocoding of IP address. The one I've used is GeoIP, which has a free version.

Note that IP addresses can be spoofable, so anyone wanting to get around your check will be able to. Any serious hackers won't be very deterred.