Wait, do you think when an ISP assigns someone an IP address, that address can never be used again even if the IP isn't assigned to the person anymore?
Of course it can. I am saying that is part of the problem. Because there are a limited number of IP addresses, it definitely will be assigned again. But that, in itself creates problems. How do sites like TPU permanently ban JoeBadGuy if he keeps coming back, but with a new username? They ban the IP address, right? So then what happens if you get JoeBadGuy's old IP? You are banned before you can even start here. So ISPs avoid IP addresses getting assigned and re-assigned willy-nilly.
It is just like phone numbers in the US. There is a limited number per area code. There's even a limited number of area codes. I got a new cell phone last year and decided to get a new phone number with it. Big mistake.
On the way home from the phone store, I got a spam text from bill collectors for "Meghan" - the previous holder of that phone number! To this day, I get a dozen or so text messages and robo-calls a week for her.
Seriously, look how IP pools work, its like networking 101.
I know how the pools work. I used to manage one. But pools are not bottomless oceans.
Each ISP has a different DHCP lease times that determine how long before an IP is
This is true. And 25+ years ago when I first got broadband (Cox cable Internet) in my home, all I had to do to get a new IP address was unplug my modem for 24 hours plus 1 or 2 minutes, plug in the modem again and I got a new IP. Today, I can leave my modem disconnected while away from home for 3 weeks (as I was earlier this year), come back and still have the same IP.
FTR, I am
NOT saying my account # with my ISP and my IP address are tied together as part of any network/DHCP "protocol" connecting my network to theirs. My apologies if I was unclear there.
I am saying it is typical SOP (standard operating procedure) or ISP "policy". That is, I am saying in the ISP's "billing" data base, my assigned IP is linked to my account number, which of course is tied to my physical address, my modem and my modem's MAC address. And unless I call up and give them a convincing story as to why I need a different IP address, that IP is mine - permanently until I terminate my service with them.
I buy my own modems (I don't rent from my ISP). And as I noted above, I have upgraded my modem 3 or 4 times over the years. New modems of course have new MAC addresses. Yet after getting my new modems, I still have the same IP address I've had for years - and that was by my ISP's "policy" they use to manage their pool. I don't believe Cox is unique in how they manage their pool.
But I could be wrong. So I would ask those of you who are saying your ISP doesn't assign your IP to your account to give them a call and ask for a new IP address assignment. If they don't have a policy tying them together, it should take all of 60 seconds to get a new one. Let us know how cooperative they are and how easy it is to get a new one. I know for a fact, as someone who was a network manager for a big network, that technically, for someone with the proper admin credentials, it is a simple task that can be done in a few seconds.
But will the ISP's policy allow it? I hope it is as simple as some here are suggesting. But I will not be surprised if not.
Getting around that is almost as easy for a fairly talented badguy as getting around disabled SSID broadcasting. MAC filtering certainly can help with limiting the number of connections to your own network. But it is not really a security precaution because it is not an effective barrier at blocking unauthorized access by a knowledgeable badguy determined to get in.
But why bother spoofing your IP or using your network?
Badguys (or mischievous neighborhood whizkids) might do this to hide their own dubious or illegal activities. Or a disgruntled or rejected X might do this to bring unwanted attention on you. As far as using your network - that is a common practice on metered networks. They use your bandwidth instead of theirs. Or perhaps they don't even have Internet.