This is the .NET API for reading MaxMind DB files. MaxMind DB is a binary file
format that stores data indexed by IP address subnets (IPv4 or IPv6).
Installation
NuGet
We recommend installing this library with NuGet. To do this, type the
following into the Visual Studio Package Manager Console:
install-package MaxMind.Db
Usage
Note: For accessing MaxMind GeoIP2 databases, we generally recommend using
the GeoIP2 .NET API rather than using this package directly.
To use the API, you must first create a Reader object. The constructor for
the reader object takes a string with the path to the MaxMind DB file.
Optionally you may pass a second parameter with a FileAccessMode enum with
the value MemoryMapped or Memory. The default mode is MemoryMapped,
which maps the file to virtual memory. This often provides performance
comparable to loading the file into real memory with the Memory mode while
using significantly less memory.
To look up an IP address, pass a System.Net.IPAddress object to the
Find<T> method on Reader. This method will return the result as type T.
T may either be a generic collection or a class using the
[MaxMind.Db.Constructor] attribute to declare which constructor to use
during deserialization and the to map the
database key to a particular constructor parameter.
[MaxMind.Db.Parameter("name")]
name
We recommend reusing the Reader object rather than creating a new one for
each lookup. The creation of this object is relatively expensive as it must
read in metadata for the file.
Example Decoding to a Dictionary
using (var reader = new Reader("GeoIP2-City.mmdb"))
{
var ip = IPAddress.Parse("24.24.24.24");
var data = reader.Find<Dictionary<string, object>>(ip);
...
}
Example Decoding to a Model Class
using MaxMind.Db;
using System.Net;
namespace MyCode
{
public class Asn
{
[Constructor]
public AsnResponse(
// The Parameter attribute tells the reader to map the database
// key to the specified constructor parameter.
[Parameter("autonomous_system_number")] long? autonomousSystemNumber,
[Parameter("autonomous_system_organization")] string autonomousSystemOrganization,
// The Inject attribute allows you to inject arbitrary values
// when deserializing.
[Inject("ip_address")] IPAddress ipAddress),
// The Network attribute tells the reader to set the constructor
// parameter to be the network associated with the record in the
// database.
[Network] Network network
{
...
}
...
}
public class Program
{
private static void Main(string[] args)
{
using (var reader = new Reader("GeoLite2-ASN.mmdb"))
{
var ip = IPAddress.Parse("24.24.24.24");
var injectables = new InjectableValues();
injectables.AddValue("ip_address", ip);
var data = reader.Find<Asn>(ip, injectables);
...
}
}
}
}
Multi-Threaded Use
This API fully supports use in multi-threaded applications. In such
applications, we suggest creating one Reader object and sharing that among
threads.
Format
The MaxMind DB format is an open format for quickly mapping IP addresses to
records. See
the specification
for more information on the format.
