Network Forensics by Ric Messier

Author:Ric Messier
Language: eng
Format: epub, pdf
ISBN: 9781119329183
Publisher: John Wiley & Sons, Inc.

Geolocation

When Voice over IP (VoIP) services became commonplace, there was a challenge. Federal regulations require telecommunications providers to be able to support enhanced 911 (E-911) services to phone subscribers. Anyone dialing 911 should be able to be located by the phone network. In a traditional phone network, this is easy because the phones are hard-wired to the central office and each subscriber has an address associated with it. If a call comes from a particular phone number using a wired line, it's guaranteed that the call has come from a specific physical address because hard-wired lines can't be moved. When the caller dials 911, the central office knows which public service access point (PSAP) to route the call to.

VoIP, though, uses interface devices that convert traditional phones and the signals they use to IP. These devices can be taken anywhere. As long as they can get an IP address and can communicate with the servers within the VoIP provider network, there is nothing to prevent the service from being used. That, however, causes problems for the service providers because they are required to be able to hand off location information for their subscriber. As noted earlier, there is nothing inherent about an IP address that can provide physical addresses, and while it is possible to read hostnames and network paths to get some location out of them, the hostname and network path don't have nearly the specificity required by E-911.

At a minimum, the service provider needs to be able to know which PSAP to route the call to. There are a number of ways to do this, including just hard-coding the subscriber into a database associated with a particular PSAP. VoIP services are not the only ones where location information from IP addresses is important or at least very useful. As a result, there are databases that will keep track of that information, as well as web interfaces that can perform lookups from IP addresses. In fact, some of these websites will tell you where you are based on your IP address.

As it turns out, a number of geolocation providers and some of the websites that you can do lookups from will provide information from the different databases. Just to demonstrate some of the challenges associated with looking up geographic location from an IP address, you will sometimes get different locations. To highlight that point, Figure 6.4 shows location information related to an IP address belonging to Google. This is information from three different databases, though the site in question, www.iplocation.net, provides results from many other databases. While two of them appear to show the same location, when you look at the latitude and longitude, they are quite different. The two showing the same city will map to very different locations.

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