Check if an ip address is static or dynamic

[ggrot]

I'm not sure if this is the right forum for this, it could fit under quite a few.

I'm working on some scripts that would let an admin perform ip banning on a user when it is appropriate. I would like to be able to give the admin some type of feedback regarding whether the ip is part of a dynamic block (AOL, dial-ups, etc) or if the ip is likely a static one(cable modems, dsl, university, etc). I was wondering if anyone knew of a good resource that would give me some ip blocks of common ISPs that I could use?

[Tapolyai]

First a quick correction - xDSL and cable modem connections are supposed to be dynamically allocated, unless specifically requested (and often getting a surcharge) to be static.

There is no direct way to figure out if something is dynamic or static. You might be able to build a database of your own, but nothing to guarantee it will not be worthless a months down the road.

Not just that, definition of dynamic becomes obscure as you move down the path of corporate networks. For example if you look at my IP now it would be the same IP as 350 other people. Should you ban me, you also ban all other users. This is because I am behind a firewall which acts to the outside world as a single IP address machine.

I have been searching for something similar because of my polling package, but the best so far I came up with is a hash of the IP and the browser, and tossing a cookie onto the machine.

An alternative that I have thought of hashing the browser and a traceroute, but dropping the last IP address. this would block a whole subnet but can be automated easier then programming the subnet.

I tried various combination thereof but no cigar - at least not Cuban...

Let me know if you come up with an ingenious idea.

[ggrot]

I really like the idea of hashing the browser string and ip. That would significantly reduce banning the innocent. I think the cookie is weak, because anyone persistant would likely turn off cookies.

I realize there is no way of calculating whether an ip is static or dynamic, but certain ip classes are pretty strong cases for each, such as AOL or Harvard ip ranges. A database may not be complete, but it would be somewhere to start, Im trying to find if such a thing may exist.

As for cable/dsl, I wasn't aware that they were dynamically assigned. My home cable for example always has the same ip address. I simply assumed all cable/dsl networks were done this way.

Thats also a very good point about the single point of contact with the routers/firewalls.

Interesting problem. I'll have to think some more on this.