ip blocking someone with dynamic dns

so I'm trying to think of an ip blocking system, and i figure i could store a list of forbidden ips in a database and then prevent people with th开发者_如何学JAVAose ips from accessing the site using php or something...

but then how do i effectively handle those with dynamic ip addresses from dynamic dns?

any good suggestions?

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Dynamic DNS (fakepc.dyndns.org) is the per-computer-voluntary ability to register its numeric IP address (127.127.127.127) each time it changes, under a specific voluntarily-constant DNS 'friendly name'. It allows you to find a specific computer's numeric IP address as it moves around, given that unchanging DNS 'friendly name'.

Dynamic DNS is probably unrelated to your goals for a blocking system for any traditionally functioning web browsers. The majority of the population doesn't have Dynamic DNS enabled. If they do, they could be using multiple computers/IP addresses with the same DNS address... or the converse. DNS won't really help you establish identity for users. Even when a person has a consistently-applied Dynamic DNS name, a web server typically can't determine what that is. By that, I mean your server can't readily convert from IP Address to Dynamic DNS address, only the other way around.

IP addresses themselves can also change over time, but this is typically less by user choice (instead, for example, occurring after month-long periods of inactivity with their ISP). Certainly the average user will see a fairly consistent IP address associated with all the PCs in their home from month-to-month. However, I can just take my laptop and go to StarBucks, I'll get a different IP and if I've cleared all my browser cookies, etc. you can't tell that it's me without personal identification.

The network service that provides IP addresses dynamically is 'DHCP'.

At the end of the day, IP addresses aren't a good per-user blocking strategy, but only you can judge if the frequency of false-positives and false-negatives from any automated IP address blocking system would be appropriate to your solution.

You might get greater benefit from an automated whitelisting system using IP addresses, rather than a blacklisting system, if your goal is to reduce the effort of users proving goodwill over time.