How to map IPs to country for free with .NET and IP2Location

We do a lot of enrichments when processing log messages from our users. One of them being a mapping from IP address to a location. We use a commercial database from IP2Location, but you can map IP addresses to location for free using their Lite dataset and .NET. In this post, I'll show you how to do that.

Before we begin, I want to put a few words on IP2Location. We are not affiliated with IP2Location in any way and I only use that service since that is what we are using on elmah.io. There are a lot of both downloadable and REST-based IP-to-country resources and services out there. If you want a high match rate you typically need to pay.

With that out of the way, let's start coding. For this blog post, I'll map an IP to a country, but there are options available for mapping to city, latitude/longitude, etc. Start by downloading the IP2Location LITE Database from here: https://lite.ip2location.com/database/ip-country. I will use the IPV4 BIN option. Next, create a new .NET Console application:

dotnet new console

Then, install the IP2Location.IPGeolocation NuGet package:

dotnet add package IP2Location.IPGeolocation

Copy and paste the IP2LOCATION-LITE-DB1.BIN file to the root of the new project and include it as part of the build output.

To map an IP address to a country you will need an instance of the Component class provided by the IP2Location.IPGeolocation package:

Component ip2location = new Component
{
    IPDatabasePath = "IP2LOCATION-LITE-DB1.BIN",
    UseMemoryMappedFile = true,
};

In this example the Component class is created every time we run the console application. But if you are developing a long-running application like a Windows Service, you want to share the instance as a singleton. I have also set UseMemoryMappedFile to true to have IP2Location read the bin file into memory and creating lookups without having to touch the file.

Next, we will fetch a user-provided IP address and convert it to a country:

var ip = args[0];
var ipResult = ip2location.IPQuery(ip);
Console.WriteLine(ipResult.CountryLong);
Console.WriteLine(ipResult.CountryShort);

When running the code, the country full name (CountryLong) as well as the ISO Alpha-2 country code (CountryShort):

United States of America
US

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