How to get client IP address in Azure Functions C#?

Question

I'm writing a function in C# using Azure Functions and need to get the ip address of the client that called the function, is this possible?

Answer 1

Here is an answer based on the one here.

#r "System.Web"

using System.Net;
using System.Web;

public static HttpResponseMessage Run(HttpRequestMessage req, TraceWriter log)
{
    string clientIP = ((HttpContextWrapper)req.Properties["MS_HttpContext"]).Request.UserHostAddress;
    return req.CreateResponse(HttpStatusCode.OK, $"The client IP is {clientIP}");
}

Answer 2

you should use these function Get the IP address of the remote host

request.Properties["MS_HttpContext"] is not available if you debug precompiled functions local request.Properties[RemoteEndpointMessageProperty.Name] is not available on azure

private string GetClientIp(HttpRequestMessage request)
{
    if (request.Properties.ContainsKey("MS_HttpContext"))
    {
        return ((HttpContextWrapper)request.Properties["MS_HttpContext"]).Request.UserHostAddress;
    }

    if (request.Properties.ContainsKey(RemoteEndpointMessageProperty.Name))
    {
        RemoteEndpointMessageProperty prop;
        prop = (RemoteEndpointMessageProperty)request.Properties[RemoteEndpointMessageProperty.Name];
        return prop.Address;
    }

    return null;
}

Update 21.08.2018: Now Azure Functions are behind a LoadBalancer --> we have to inspect Request-Headers to determine the correct Client IP

private static string GetIpFromRequestHeaders(HttpRequestMessage request)
    {
        IEnumerable<string> values;
        if (request.Headers.TryGetValues("X-Forwarded-For", out values))
        {
            return values.FirstOrDefault().Split(new char[] { ',' }).FirstOrDefault().Split(new char[] { ':' }).FirstOrDefault();
        }

        return "";
    }

Answer 3

Here is an extension method based on what I am seeing in

.Net Core 3.1

public static IPAddress GetClientIpn(this HttpRequest request)
{
    IPAddress result = null;
    if (request.Headers.TryGetValue("X-Forwarded-For", out StringValues values))
    {
        var ipn = values.FirstOrDefault().Split(new char[] { ',' }).FirstOrDefault().Split(new char[] { ':' }).FirstOrDefault();
        IPAddress.TryParse(ipn, out result);
    }
    if (result == null)
    {
        result = request.HttpContext.Connection.RemoteIpAddress;
    }
    return result;
}

.NET 6.+

        public static IPAddress GetClientIpn(this HttpRequestMessage request)
        {
            IPAddress result = null;
            if (request.Headers.TryGetValues("X-Forwarded-For", out IEnumerable<string> values))
            {
                var ipn = values.FirstOrDefault().Split(new char[] { ',' }).FirstOrDefault().Split(new char[] { ':' }).FirstOrDefault();
                IPAddress.TryParse(ipn, out result);
            }
            return result;
        }

Answer 4

Now that Azure functions get an HttpRequest parameter, and they're behind a load balancer, this function to get the IP address works for me:

private static string GetIpFromRequestHeaders(HttpRequest request)
{
      return (request.Headers["X-Forwarded-For"].FirstOrDefault() ?? "").Split(new char[] { ':' }).FirstOrDefault();
}

Answer 5

Update 18-Oct-2019:

The solution I tried is much easier and quicker and is mentioned below stepwise. But some more lengthy/tricky alternates are available @ https://learn.microsoft.com/en-us/azure/azure-monitor/app/ip-collection:

1. Login into Azure portal.
2. Open a new tab in same browser while you are logged in and dial “http://Resources.Azure.Com”
3. This is Azure back end services portal so being slightly careful in making changes would be great.
4. Expand SUBSCRIPTIONS section from the left panel and expand your Azure Subscription where app insight resource is located.
5. Expand Resource Groups section and expand the Resource Group where app insights resource is.
6. Expand the Providers section and find the Microsoft.Insights provider and expand it.
7. Expand the Components section and find and select your App Insight Instance by name.
8. On the right top change your mode to Read Write from Read Only.
9. Click EDIT button on the Rest API call.
10. ADD NEW “"DisableIpMasking": true property to properties section.
11. Press PUT button to apply changes.
12. Now your App Insight is enabled to start collecting Client IP addresses.
13. Do some queries on the Function.
14. Refresh and Test the App Insights data after about 5 to 10 minutes.

Answer 6

As mentioned already by others, the old method of looking at MS_HttpContext no longer works. Further, while the method of looking at the headers for X-Forwarded-For does work, it only works after being published in Azure - it doesn't return a value when you're running locally. That may matter if you prefer testing locally to minimize any potential cost-impact, but still want to be able to see that everything works correctly.

To see the IP address even when running locally, try this instead:

using Microsoft.AspNetCore.Http;

And then:

String RemoteIP = ((DefaultHttpContext)req.Properties["HttpContext"])?.Connection?.RemoteIpAddress?.ToString();

This is working for me currently in Azure Functions V3.0.

Answer 7

In a .NET 6.0 function, within the Run() function of the operation, this can be accessed of the HttpRequest req object:

    public static class PingOperation
    {
        [FunctionName("ping")]
        public static async Task<IActionResult> Run(
            [HttpTrigger(AuthorizationLevel.Function, "get", "post", Route = null)] HttpRequest req,
            ILogger log)
        {
            string requestBody = await new StreamReader(req.Body).ReadToEndAsync();

            log.LogInformation($"PingOperation requested from: {req.HttpContext.Connection.RemoteIpAddress}:{req.HttpContext.Connection.RemotePort}");

            string responseMessage = "This HTTP triggered function executed successfully.";

            return new OkObjectResult(responseMessage);
        }
    }