I've seen some questions around the web regarding this, this version will return a string with the client IP. If it returns ::1 that means the client is requesting from the same computer as where the API is running. The query address will be something like http://yoursite/api/ip depending on your routing.
using System.Net.Http; using System.ServiceModel.Channels; using System.Web; using System.Web.Http; namespace Trikks.Controllers.Api { public class IpController : ApiController { public string GetIp() { return GetClientIp(); } private string GetClientIp(HttpRequestMessage request = null) { request = request ?? Request; if (request.Properties.ContainsKey("MS_HttpContext")) { return ((HttpContextWrapper)request.Properties["MS_HttpContext"]).Request.UserHostAddress; } else if (request.Properties.ContainsKey(RemoteEndpointMessageProperty.Name)) { RemoteEndpointMessageProperty prop = (RemoteEndpointMessageProperty)this.Request.Properties[RemoteEndpointMessageProperty.Name]; return prop.Address; } else if (HttpContext.Current != null) { return HttpContext.Current.Request.UserHostAddress; } else { return null; } } } }