How can someone find out who I am?

A little background first.

IP address allocation is handled by The Internet Assigned Numbers Authority (IANA). IANA in turn, delegate authority to Regional Internet Registries (RIRs). The RIRs, in turn, following their own regional policies, further delegate blocks of IP addresses to their customers, which include Internet Service Providers (ISPs) and end-user organizations.

Each of the RIRs handles a specific geographic area:

• ARIN (North America and portions of the Caribbean)
• AfriNIC (Africa)
• APNIC (Asia and the Pacific region)
• LACNIC (Latin America and portions of the Caribbean)
• RIPE (Europe, Middle East, Central Asia)

Each of these organizations allow lookups to be to that data. Different ISP's segment their blocks of IP addresses by region and you can see that in the lookup. The lookup provides the name and address of the organization the block of IP addresses was allocated to. The ISP's can name these blocks if they choose. The naming often indicates a geographic location, for example, IRV-CA, aka Irvine, California.

Here are links to the URLs where you can lookup an IP address. Be aware that if you lookup an Asian allocated IP address in a different region's RIR it will provide a link to the appropriate RIR.

• North America and portions of the Caribbean
• Africa
• Asia and the Pacific region
• Latin America and portions of the Caribbean
• Europe, Middle East, and Central Asia

In general, I start by looking up an IP address with ARIN seeing what geographic location information I can learn from the results.

From there I do a reverse DNS (rDNS) lookup to see what hostname the ISP provides. A hostname is something like www.example.com, or can be more specific to include regional information. By visiting this page you can see your own rDNS/hostname. (We'll add the functionality to lookup other IP addresses soon.) This, again, can provide some additional geographic location information.

From there I do a traceroute which displays the hostnames many of the machines in between two points on the internet. (I'm making this *really* none technical here...) Sometimes the rDNS/hostname of a specific IP address will not reveal any location but the rDNS/hostname of the machine next along the path will reveal some.

That's about all the information that can be obtained without a subpoena. In many cases people reveal small amounts of personal information about themselves on forums, chat rooms, blogs, etc that can be used to build a profile of who you might be.

Try using this tool to look up your IP address.