Search  
Always will be ready notify the world about expectations as easy as possible: job change page
Articles
Dec 23, 2023

How to get client IP address and location information in ASP.NET Core

How to get client IP address and location information in ASP.NET Core
Source:
Views:
4199

This article will teach us how to retrieve the client’s IP address and location information in ASP.NET Core web development.

Retrieve the client IP from HttpContext

In ASP.NET Core, you can easily get the client IP address from the HttpContext object in the Controller, making it simple to access this important information during a web request:

public class MyIpController : ControllerBase
{
    [HttpGet]
    public ActionResult Get()
    {
        var ipAddress = HttpContext.Connection.RemoteIpAddress?.ToString();
        // ...
    }
}

This approach works well when our application is directly exposed to the internet, operating without the intermediary layer of a reverse proxy.

Retrieve real client IP behind reverse proxy

However, it’s common for most web applications to use intermediary layers such as reverse proxies or load balancers in their architecture.

The direct retrieval method might yield the proxy IP instead of the client’s.

To obtain the actual client’s IP address, we can extract it from the ‘X-Forwarded-For’ header value.

To do this, we have to configure the ForwardHeaderOptions in the Program.cs first:

// forward headers configuration for reverse proxy
builder.Services.Configure<ForwardedHeadersOptions>(options => {
    options.ForwardedHeaders = ForwardedHeaders.XForwardedFor | ForwardedHeaders.XForwardedProto;
    options.KnownNetworks.Clear();
    options.KnownProxies.Clear();
});

Then, in the Controller, we can retrieve the actual client IP address:

public class MyIpController : ControllerBase
{
    [HttpGet]
    public ActionResult Get()
    {
        var ipAddress = HttpContext.GetServerVariable("HTTP_X_FORWARDED_FOR");
        // ...
    }
}

Retrieve real client IP behind Cloudflare

If we use Cloudflare, we can access the real client IP from the ‘CF-CONNECTING-IP’ header:

public class MyIpController : ControllerBase
{
    [HttpGet]
    public ActionResult Get()
    {
        var ipAddress = Request.Headers["CF-CONNECTING-IP"];
        // ...
    }
}

Get the client’s IP location information

To obtain location information based on the client’s IP address, we will utilize the services provided by ip-api.com.

First, we create the IpApiClient class:

public class IpApiClient(HttpClient httpClient)
{
    private const string BASE_URL = "http://ip-api.com";
    private readonly HttpClient _httpClient = httpClient;

    public async Task<IpApiResponse?> Get(string? ipAddress, CancellationToken ct)
    {
        var route = $"{BASE_URL}/json/{ipAddress}";
        var response = await _httpClient.GetFromJsonAsync<IpApiResponse>(route, ct);
        return response;
    }
}

The IpApiResponse class:

public sealed class IpApiResponse
{
    public string? status { get; set; }
    public string? continent { get; set; }
    public string? country { get; set; }
    public string? regionName { get; set; }
    public string? city { get; set; }
    public string? district { get; set; }
    public string? zip { get; set; }
    public double? lat { get; set; }
    public double? lon { get; set; }
    public string? isp { get; set; }
    public string? query { get; set; }
}

We need to add and register the HttpClient for IpApiClient within the service container, which can be done in the Program.cs file:

builder.Services.AddHttpClient<IpApiClient>();

Now we can retrieve the client’s IP location information:

[HttpGet]
public async Task<ActionResult> Get(CancellationToken ct)
{
    try
    {
        var ipAddress = HttpContext.GetServerVariable("HTTP_X_FORWARDED_FOR") ?? HttpContext.Connection.RemoteIpAddress?.ToString();
        var ipAddressWithoutPort = ipAddress?.Split(':')[0];

        var ipApiResponse = await _ipApiClient.Get(ipAddressWithoutPort, ct);

        var response = new
        {
            IpAddress = ipAddressWithoutPort,
            Country = ipApiResponse?.country,
            Region = ipApiResponse?.regionName,
            City = ipApiResponse?.city,
            District = ipApiResponse?.district,
            PostCode = ipApiResponse?.zip,
            Longitude = ipApiResponse?.lon.GetValueOrDefault(),
            Latitude = ipApiResponse?.lat.GetValueOrDefault(),
        };

        return Ok(response);
    }
    catch (Exception ex)
    {
        return StatusCode(StatusCodes.Status500InternalServerError, ex.Message);
    }
}

Sometimes, the client IP includes a port number.
We can remove the port number using the following code:

var ipAddressWithoutPort = ipAddress?.Split(':')[0];

• • •

I created a simple application to showcase the concepts discussed in this article:

MYIPJUL

The source code for that application can be found here:

GitHub - juldhais/MYIP: Example of how to retrieve client’s IP and location in ASP.NET Core

Thank you for reading. 👍

Files

Similar
Jul 8, 2021
Author: Christophe Nasarre
In the context of helping the teams at Criteo to clean up our code base, I gathered and documented a few C# anti-patterns similar to Kevin’s publication about performance code smell. Here is an extract related to good/bad memory patterns....
Jun 7
Author: Dev Leader
In software engineering, composition plays an important role in object-oriented programming. If you’ve come across other articles or videos I’ve put out about object-oriented programming, you’ll know that I try to push composition over inheritance as much as I can....
Apr 8
Author: Dev Leader
async void methods in C# are a source of a lot of problems for many developers getting into writing async await code. The pattern that we’re suggested to use is of course async Task, but there are cases — like...
Nov 30, 2023
Author: Dev·edium
QUIC (Quick UDP Internet Connections) is a new transport protocol for the Internet that runs on top of User Datagram Protocol (UDP) QUIC (Quick UDP Internet Connections) is a new transport protocol for the Internet that runs on top of...
Send message
Type
Email
Your name
*Message