So-called geolocation systems attempt to map IP addresses to geographic locations using large computer databases. Some geolocation databases are available for sale, and some can also be searched for free online. Does this geolocation technology really work?
How Is IP Address Location Used?Geolocation can be used in several different cases:
Managing Web sites - Webmasters can use a geolocation service to track the geographic distribution of visitors to their site. Besides satisfying general curiosity, advanced Web sites can also dynamically change the content shown to each visitor based on their location. These sites may also block access to visitors from certain countries or locales.
Finding spammers - Individuals being harassed online often want to trace the IP address of email or instant messages.
Enforcing the law - The Recording Industry Association of America (RIAA) and other agencies may use geolocation to find people illegally swapping media files on the Internet, although typically they work directly with Internet Service Providers (ISPs).
What Are the Limitations of Geolocation?IP address location databases have greatly improved in accuracy over the years. They may attempt to map each network address to a specific postal address or latitude/longitude coordinate. However, various limitations still exist:
- IP addresses may be associated with the wrong location (e.g., the wrong postal code, city or suburb within a metropolitan area).
- Addresses may be associated only with a very broad geographic area (e.g., a large city, or a state). Many addresses are associated only with a city, not with a street address or latitude/longitude location.
- Some addresses will not appear in the database and therefore cannot be mapped (often true for IP numbers not commonly used on the Internet).
Can WHOIS Be Used for Geolocation?The WHOIS database was not designed to locate IP addresses geographically. WHOIS tracks the owner of an IP address range (subnet or block) and the owner's postal address. However, these networks may be deployed in a different location than that of the owning entity. In the case of addresses owned by corporations, addresses also tend to be distributed across multiple different branch offices. While the WHOIS system works well for finding and contacting owners of Web sites, it is a highly inaccurate IP location system.
Where Are Some Geolocation Databases?Several online services allow you to search for the geographic location of an IP address by entering it into a simple Web form. Two popular services are Geobytes and IP2Location. Each of these services utilizes a proprietary databases of addresses based on Internet traffic flow and Web site registrations. The databases were designed for use by Webmasters and can be purchased as a downloadable package for that purpose.
What Is Skyhook?A company named Skyhook Wireless has built a geolocation database of a different kind. Their system is designed to capture the Global Positioning System (GPS) location of home network routers and access points, which may also include residential street addresses. The Skyhook system is not publicly available. However, its technology is being used in the AOL Instant Messenger (AIM) "Near Me" plug-in.
What About Hotspot Databases?Thousands of wireless hotspots are available for public use around the world. Various online databases exist for finding Wi-Fi hotspots which map a hotspot's location including its street address. These systems work well for travelers seeking Internet access. However, hotspot finders provide only the network name (SSID) of the access point and not its actual IP address.
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