1、第一种方法

1）在Startup.cs中ConfigureSerivces中配置

services.Configure<ForwardedHeadersOptions>(options =>
{
    options.ForwardedHeaders = ForwardedHeaders.XForwardedFor | ForwardedHeaders.XForwardedProto;
});

2）获取IP代码

string remoteIpAddress = HttpContext.Connection.RemoteIpAddress.MapToIPv4().ToString();
if (Request.Headers.ContainsKey("X-Forwarded-For"))
    remoteIpAddress = Request.Headers["X-Forwarded-For"];

2、第二种方法

1）在Startup.cs中ConfigureSerivces中配置

public void ConfigureServices(IServiceCollection services)
{
    services.AddSingleton<IHttpContextAccessor, HttpContextAccessor>();
}

2）在控制器(Controller)中获取IP

private IHttpContextAccessor _accessor;
public ValuesController(IHttpContextAccessor accessor)
{
    _accessor = accessor;
}
public IEnumerable<string> Get()
{
    var ip = _accessor.HttpContext?.Connection?.RemoteIpAddress?.ToString();
    return new string[] { ip, "value2" };
}