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

Often the primary source of data for these databases is Whois records. Specifically the country with legal authority over the IP resources. In this way a company registered in Australia who is announcing resources in the US can have their ranges geolocated by a database to Australia.

There are some descriptors that can be put in whois listings that are honoured by some databases. For example, the descr: field can be used to specify a location. However, this is not a standard field and is not always honoured.

Due to this data being sourced from whois records it needs to be scraped. This is a slow ratelimited process which limits the update frequency and hence accuracy of databases.

Update freqency

Databases are often updated infrequently and deployed by their users to production environments at further delays. This means that the IP addresses in the database may not be up-to-date, and the location information associated with them may be inaccurate.

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. The service is provided by routing traffic to the closest server based on geographic location. 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.

Most typical GeoIP databases include only a single location entry (country code) for a given IP address and can not support the multiple locations of Anycast adresses.

Minimum size of an entry

As the minimum size of a route (more information) is 24 bits, the minimum size of an entry in a GeoIP database is 24 bits. This means that the smallest geographic location that can be typpically represented in a GeoIP database is a /24 network. This is not a limitation of all formats and databases but is often a decision made by database providers to limit the size of the database.

In summary, GeoIP is a powerful technology that can be used for a variety of applications, but there are several limitations to its accuracy. IP addresses are often reassigned to different locations, VPNs and proxies can be used to bypass GeoIP, hosting services can affect GeoIP accuracy and Anycast services can cause inaccuracies in GeoIP databases. These limitations should be considered when using GeoIP data and organizations should evaluate the accuracy of their GeoIP data before making important decisions or taking actions based on 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 isnt if the method used to forward traffic (e.g VPN) is secure.

Miss-use 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 miss-used to damaging effect to your business or service. There are a number of ways this can happen. We encourage you to consider other options, expecially if the integration of GeoIP is a permanant 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 miss-identified (positive or negative) - If the restriction is a good idea in the first place

Assuming you stilL want to proceed we would advise that you: - Use region restrictions instead of GeoIP data (i.e allow all traffic that arrives via the Amsterdam datacenter) - 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 maintenence and traffic is re-routed - What happens if the user is miss-identified (positive or negative) - What affect 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.