Limitations of GeoIP Accuracy

GeoIP is a technology that maps IP addresses to geographic locations. It is used for a variety of applications such as targeted advertising, content delivery, and network security. However, there are several limitations to the accuracy of GeoIP that should be considered when using it.

Source of data

Providers combine sources such as network-operator information, geofeeds, registration data and observed signals. The country in an address registration can differ from the location where the address is used. For example, an Australian company may operate its addresses in the US.

Use the database provider's correction process when an entry is wrong. A WHOIS description, such as a descr: field, can supply context, but providers interpret it differently; changing it alone may not update the location estimate.

Update frequency

Collecting and checking changed network information takes time. Database publication and deployment are then separate steps. A provider may correct an entry before an application downloads the updated database. Check the provider's update schedule and your application's refresh process when investigating a mismatch.

IP Address Reassignment

One of the main limitations of GeoIP is that IP addresses are often reassigned to different locations. This means that an IP address that was previously associated with a specific geographic location may now be associated with a different location. This can happen when an Internet Service Provider (ISP) reallocates IP addresses to different customers or when a customer changes their location.

Anycast IPs

Anycast services are a method of providing a single IP address to multiple servers located in different geographic locations. Routing policy and network topology determine which server receives a connection. However, this can cause inaccuracies in GeoIP databases since the same IP address may be associated with multiple geographic locations. This can cause issues for organizations that rely on GeoIP data to target specific regions or for security purposes.

A database may return a single location for an anycast address even though visitors reach different servers. Check how the provider represents anycast locations.

Minimum size of an entry

Geolocation databases choose their own address ranges and level of detail. These are independent of the prefixes accepted by Internet routing. Coarser ranges reduce the number of database entries but can combine addresses used in different locations. For example, the MaxMind database format supports IPv4 and IPv6 lookups without a universal /24 minimum for entries.

Address reassignment, VPNs, proxies and anycast can all affect accuracy. Evaluate the database against the decisions you want to make with it.

Fitness for purpose (what do you mean by location)

Another limitation of GeoIP is that it can be easily bypassed by users who are connected to Virtual Private Networks (VPNs) or using proxy servers. These technologies allow users to appear as if they are located in a different geographic location, making it difficult for GeoIP to accurately determine their true location. This may be the location you are after, or not.

When accessed in this manner or by services run in datacenter the original location of the user is obscured (by choice or effect). It may not be possible to know the original location of the user and likely isn't if the method used to forward traffic (e.g VPN) is secure.

Misuse of GeoIP

When restricting content to certain countries or regions it is important to consider that a person being restricted may be a legitimate customer. For example, a person in the US may be using a VPN to access your service from a country where it is not available. This may be because they are travelling or because they are a legitimate customer who has moved to a country where your service is not available. And one thing you can be reasonably certain of is that they will be inconvenienced and potentially lost to you should they be explicitly rejected.

GeoIP can be misused to damaging effect to your business or service. There are a number of ways this can happen. We encourage you to consider other options, especially if the integration of GeoIP is a permanent feature of your service.

We at X4B really hope for an open and healthy internet and we encourage you to consider the impact of your decisions on the internet as a whole.

Restricting traffic to a service from a region

If you are using GeoIP to restrict traffic to a service from a specific region, you should consider the following:

  • The accuracy of the GeoIP data
  • What happens if the user is misidentified (positive or negative)
  • If the restriction is a good idea in the first place

If you want to proceed we would advise that you:

  • Use ingress-region rules for requirements about where traffic enters the service (for example, the Amsterdam datacenter). Assess visitor-location requirements separately.
  • Do not hard block traffic in any location
  • Continue to define routing rules for all regions for redundancy

When using this method you will also need to consider:

  • What happens if there is route or datacenter maintenance and traffic is re-routed
  • What happens if the user is misidentified (positive or negative)
  • What effect IP spoofing will have

Do we offer GeoIP based rules?

We offer GeoIP based rules for Layer 7 usage. This database is regularly updated and maintained by automated scripts on our end. Of course accuracy in this database is not guaranteed and is subject to many of the same limitations of other databases.

We do not offer GeoIP based rules for Layer 4 usage.

See MaxMind data sources and anycast operations for more detail.