您还可以使用api.db-ip.com web服务获取IP地址和位置。

这项服务是免费的，但有一个限制:每天1000次请求。

public string GetRemoteIP()
{
    HttpClient client = new HttpClient();
    var result = client.GetStringAsync("https://api.db-ip.com/v2/free/self").Result;
    var ip = JsonSerializer.Deserialize<RemoteIPDto>(result.ToString()).IP;
    return ip;
}
public static string GetUserAddress()
{
      HttpClient client = new HttpClient();
      var result = client.GetStringAsync("https://api.db-ip.com/v2/free/self").Result;
      var location = result.ToString();
      return remoteAddress;
}

RemoteIPDto类在哪里

public class RemoteIPDto
{
    [JsonPropertyName("ipAddress")]
    public string IP { get; set; }
    [JsonPropertyName("continentCode")]
    public string ContinentCode { get; set; }
    [JsonPropertyName("continentName")]
    public string ContinentName { get; set; }
    [JsonPropertyName("countryCode")]
    public string CountryCode { get; set; }
    [JsonPropertyName("countryName")]
    public string CountryName { get; set; }
    [JsonPropertyName("city")]
    public string City { get; set; }
}

@crokusek回答的简短版本

public string GetUserIP(HttpRequest req)
{
    var ip = req.Headers["X-Forwarded-For"].FirstOrDefault();

    if (!string.IsNullOrWhiteSpace(ip)) ip = ip.Split(',')[0];

    if (string.IsNullOrWhiteSpace(ip)) ip = Convert.ToString(req.HttpContext.Connection.RemoteIpAddress);

    if (string.IsNullOrWhiteSpace(ip)) ip = req.Headers["REMOTE_ADDR"].FirstOrDefault();

    return ip;
}

在IIS上使用负载均衡器运行。net core(3.1.4)不能与其他建议的解决方案一起工作。

手动读取X-Forwarded-For报头可以。 这段代码假设这个报头包含一个IP。

IPAddress ip;
var headers = Request.Headers.ToList();
if (headers.Exists((kvp) => kvp.Key == "X-Forwarded-For"))
{
    // when running behind a load balancer you can expect this header
    var header = headers.First((kvp) => kvp.Key == "X-Forwarded-For").Value.ToString();
    // in case the IP contains a port, remove ':' and everything after
    ip = IPAddress.Parse(header.Remove(header.IndexOf(':')));
}
else
{
    // this will always have a value (running locally in development won't have the header)
    ip = Request.HttpContext.Connection.RemoteIpAddress;
}

感谢@JawadAlShaikh和@BozoJoe指出IP可以包含一个端口，x - forward - for可以包含多个IP。

您可以使用IHttpConnectionFeature来获取此信息。

var remoteIpAddress = httpContext.GetFeature<IHttpConnectionFeature>()?.RemoteIpAddress;

试试这个。

var host = Dns.GetHostEntry(Dns.GetHostName());
        foreach (var ip in host.AddressList)
        {
            if (ip.AddressFamily == AddressFamily.InterNetwork)
            {
                 ipAddress = ip.ToString();
            }
        }

var remoteIpAddress = HttpContext.Features.Get<IHttpConnectionFeature>()?.RemoteIpAddress;