How I account for my site being behind an Amazon AWS Elastic Load Balancer (ELB):
public class GetPublicIp {
/// <summary>
/// account for possbility of ELB sheilding the public IP address
/// </summary>
/// <returns></returns>
public static string Execute() {
try {
Console.WriteLine(string.Join("|", new List<object> {
HttpContext.Current.Request.UserHostAddress,
HttpContext.Current.Request.Headers["X-Forwarded-For"],
HttpContext.Current.Request.Headers["REMOTE_ADDR"]
})
);
var ip = HttpContext.Current.Request.UserHostAddress;
if (HttpContext.Current.Request.Headers["X-Forwarded-For"] != null) {
ip = HttpContext.Current.Request.Headers["X-Forwarded-For"];
Console.WriteLine(ip + "|X-Forwarded-For");
}
else if (HttpContext.Current.Request.Headers["REMOTE_ADDR"] != null) {
ip = HttpContext.Current.Request.Headers["REMOTE_ADDR"];
Console.WriteLine(ip + "|REMOTE_ADDR");
}
return ip;
}
catch (Exception ex) {
Console.Error.WriteLine(ex.Message);
}
return null;
}
}