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();

注意:当使用localhost时，IP地址总是“0.0.0.1”，但当我在AWS EC2实例上使用Nginx托管应用程序时，我收到了正确的IP地址。

将以下包添加到您的项目中:

"Microsoft.AspNetCore.HttpOverrides": "2.2.0"

然后在Startup.cs中的Configure()方法中添加以下内容(确保将其放在app.UseStaticFiles()和app.UseRouting()之前)

app.UseForwardedHeaders(new ForwardedHeadersOptions
{
    ForwardedHeaders = ForwardedHeaders.XForwardedFor | ForwardedHeaders.XForwardedProto
});
    
// app.UseStaticFiles();
// app.UseRouting();

然后在你的控制器类中，你可以使用下面的代码获取IP地址:

IPAddress remoteIpAddress = Request.HttpContext.Connection.RemoteIpAddress.MapToIPv4()?.ToString();

using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Http.Features;

public string GetClientIPAddress(HttpContext context)
    {
        string ip = string.Empty;
if (!string.IsNullOrEmpty(context.Request.Headers["X-Forwarded-For"]))
        {
            ip = context.Request.Headers["X-Forwarded-For"];
        }
        else
        {
            ip = context.Request.HttpContext.Features.Get<IHttpConnectionFeature>().RemoteIpAddress.ToString();
        }
        return ip;
    }

你想获取Ip地址;

GetClientIPAddress(HttpContext);

@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;
}

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;

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; }
}