IP Addresses alone cannot be used to identify users?

[corydoras]

The chances are that you are accessing the net via a Network Address Translation system. In that case the big wide world never sees your IP address, it only sees the IP address of your internet service provider's local network. The same external address is used by everyone on that network. The IP you use is seen only within the ISP's local network. If anyone has information that narrows you down closer than the local network (which might be the town you live in, say) then your ISP has given them that information.

 

Sorry mate but that's just not true or at least some of it isn't. Granted that anyone accessing the internet via a ROUTER of some kind or another will have their PRIVATE IP address hidden from the outside world. Your private IP addresses should fall somewhere in the following three ranges: 10.0.0.0 – 10.255.255.255 OR 172.16.0.0 – 172.31.255.255 OR 192.168.0.0 – 192.168.255.255. Granted also that the big outside world will only see your EXTERNAL IP Address. Where you have gone wrong is with the notion that the external address is the same for everyone who uses the same ISP, that just does not make sense, nor does the notion that that address is not available to devices outside your own network. EVERY device on the Internet needs a UNIQUE IP address, just the same as every computer on your home network needs a UNIQUE IP address, just the same as every telephone subscriber needs a unique phone number.

 

Most of us will have a DYNAMIC external IP address. This means that your ISP will "lease" your router an IP address from a range allocated to them. Everyone with the same ISP will have a different IP address in the same range. This IP address will change from time to time.

 

Here's an Example. My ISP is Demon. I have a DYNAMIC IP Address from my ISP. I use the Class B Private addressing scheme.

My EXTERNAL IP address is ALWAYS in the 62.56.xxx.xxx range because those are the IP addresses allocated to Demon. This IP address will change from time to time. My ISP will keep a log of which subscriber has which IP address. The IP address on my laptop is STATIC, all other devices on the internal LAN are dynamic.

 

Service that attempt to pinpoint your position on the globe are doing this by looking up freely available information about which IP address ranges have been allocated to which ISP. They always tell me I am in London, despite the fact that I live in Southamton and my ISPs offices are in Glasgow. This is because demon's IP address range is actually managed by LINX which is in London's Docklands.

[ColinW]

EVERY device on the Internet needs a UNIQUE IP address...

 

No it doesn't. That is the whole point of Network Address Translation (NAT).

[corydoras]

No it doesn't. That is the whole point of Network Address Translation (NAT).

YOUR INTERNAL devices, behind the NAT are NOT on the INTERNET. They are on a PRIVATE network called an EXTRANET.

 

How NAT Works.

 

I hate to argue from authority but I am an ACTIVE member of the Internet Engineering Task Force and I participate in the NAT and DHCP Special Interest Groups mailing lists and contribute to the RFCs. This is my 'bread and butter".

Edited May 18, 2011 by corydoras

[ColinW]

YOUR INTERNAL devices, behind the NAT are NOT on the INTERNET.

 

That's really just an argument about semantics. My definition of a device being "on the internet" would be it being able to communicate with devices that aren't on the same local area network.

[corydoras]

That's really just an argument about semantics. My definition of a device being "on the internet" would be it being able to communicate with devices that aren't on the same local area network.

No that's not "semantics". Your PC is not on the internet and does not participate in the internet. It access the Internet through the NAT gateway in your router. Your NAT router participates on the internet on your behalf. The internet can not "see" any of the devices behind the NAT gateway and thus it cannot participate with them.