从这个环节，就有了更好的解决方案。

在Startup.cs中，我们需要添加service-

public void ConfigureServices(IServiceCollection services)
{
    ........
    services.AddHttpContextAccessor();
    ........
}

然后在任何控制器或任何地方，我们都需要像这样通过依赖注入来使用它

private IHttpContextAccessor HttpContextAccessor { get; }

public ApplicationDbContext(DbContextOptions<ApplicationDbContext> options, IWebHostEnvironment env, IHttpContextAccessor httpContextAccessor)
        : base(options)
{
    Environment = env;
    HttpContextAccessor = httpContextAccessor;
    //this.Database.EnsureCreated();
}

然后得到这样的IP

IPAddress userIp = HttpContextAccessor.HttpContext.Connection.RemoteIpAddress;

要在。net Core中获取IP地址和主机名，在控制器中输入以下代码:

var addlist = Dns.GetHostEntry(Dns.GetHostName());
string GetHostName = addlist.HostName.ToString();
string GetIPV6 = addlist.AddressList[0].ToString();
string GetIPV4 = addlist.AddressList[1].ToString();

您可以使用IHttpConnectionFeature来获取此信息。

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

也可以从外部服务获取IP。

public string GetIP()
{
    HttpClient client = new HttpClient();
    var result = client.GetStringAsync("https://jsonip.com/").Result;
    var ip = JsonSerializer.Deserialize<RemoteIPDto>(result.ToString()).IP;
    return ip;
}

RemoteIPDto类在哪里

public class RemoteIPDto
{
    [JsonPropertyName("ip")]
    public string IP { get; set; }
    [JsonPropertyName("geo-ip")]
    public string GeoIp { get; set; }
    [JsonPropertyName("API Help")]
    public string ApiHelp { get; set; }
}

运行ASP。在Ubuntu上的Traefik反向代理后面的NET Core 2.1，我需要在安装官方的Microsoft.AspNetCore.HttpOverrides包后在knownproxy中设置它的网关IP

        var forwardedOptions = new ForwardedHeadersOptions {
            ForwardedHeaders = ForwardedHeaders.XForwardedFor,
        };
        forwardedOptions.KnownProxies.Add(IPAddress.Parse("192.168.3.1"));
        app.UseForwardedHeaders(forwardedOptions);

根据文档，如果反向代理没有在本地主机上运行，这是必需的。docker-compose。Traefik . yml已分配静态IP地址:

networks:
  my-docker-network:
    ipv4_address: 192.168.3.2

或者，它应该足以确保在这里定义了一个已知的网络，并在. net Core中指定其网关。

从这个环节，就有了更好的解决方案。

在Startup.cs中，我们需要添加service-

public void ConfigureServices(IServiceCollection services)
{
    ........
    services.AddHttpContextAccessor();
    ........
}

然后在任何控制器或任何地方，我们都需要像这样通过依赖注入来使用它

private IHttpContextAccessor HttpContextAccessor { get; }

public ApplicationDbContext(DbContextOptions<ApplicationDbContext> options, IWebHostEnvironment env, IHttpContextAccessor httpContextAccessor)
        : base(options)
{
    Environment = env;
    HttpContextAccessor = httpContextAccessor;
    //this.Database.EnsureCreated();
}

然后得到这样的IP

IPAddress userIp = HttpContextAccessor.HttpContext.Connection.RemoteIpAddress;