如何在ASP.Net Core 2.x中访问服务器变量

Question

I m using ASP.Net core 2.0 web app and it is deployed on Azure. What I need to do is to get client IP Address. For this, I m searching all over the internet and found that the server variables help me on this.

So I found this code from here to get Client IP using:

string IpAddress = this.Request.ServerVariables["REMOTE_ADDR"];

But when I'm trying above code it shows me an error "HttpRequest does not contain a definition for Server Variables"

Also I was try this code:

var ip0 = HttpContext.Features.Get<IHttpConnectionFeature>()?.RemoteIpAddress;

Code Definition

RemoteIpAddress The IP Address of the client making the request. Note this may be for a proxy rather than the end user.

Above code is getting the IP address but it is not a clientip and each time when I access above code via controller it refreshes the IP. Maybe this is an Azure web service proxy which makes get request each time.

What is the right way to access server variables in ASP.Net Core 2.x?

Answer 1

You can use HttpContext.Connection to get information about the connection (IP etc)

https://docs.microsoft.com/en-us/dotnet/api/microsoft.aspnetcore.http.httpcontext.connection?view=aspnetcore-2.1

https://docs.microsoft.com/en-us/dotnet/api/microsoft.aspnetcore.http.connectioninfo.remoteipaddress?view=aspnetcore-2.1#Microsoft_AspNetCore_Http_ConnectionInfo_RemoteIpAddress

Answer 2

I found Mark G reference link very useful.

I've configure the middleware with ForwardedHeadersOptions to forward the X-Forwarded-For and X-Forwarded-Proto headers in Startup.ConfigureServices.

Here is my startup.cs code file:

public void ConfigureServices(IServiceCollection services)
{
    services.AddDbContext<ApplicationDbContext>(options =>
           options.UseSqlServer(Configuration.GetConnectionString("DefaultConnection")));

    services.AddIdentity<ApplicationUser, IdentityRole>()
            .AddEntityFrameworkStores<ApplicationDbContext>()
            .AddDefaultTokenProviders();

    services.AddIdentityServer()
            .AddDeveloperSigningCredential()
            .AddInMemoryPersistedGrants()
            .AddInMemoryIdentityResources(Config.GetIdentityResources())
            .AddInMemoryApiResources(Config.GetApiResources())
            .AddInMemoryClients(Config.GetClients())
            .AddAspNetIdentity<ApplicationUser>();

    services.AddCors(options =>
    {
        options.AddPolicy("AllowClient",
                   builder => builder.WithOrigins("http://**.asyncsol.com", "http://*.asyncsol.com", "http://localhost:10761", "https://localhost:44335")
                                  .AllowAnyHeader()
                                  .AllowAnyMethod());
        });

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

        services.AddAuthentication(options =>
        {
            options.DefaultAuthenticateScheme = JwtBearerDefaults.AuthenticationScheme;
            options.DefaultChallengeScheme = JwtBearerDefaults.AuthenticationScheme;
        })
        .AddJwtBearer(options =>
        {
            // base-address of your identityserver
            //options.Authority = "http://server.asyncsol.com/";
            options.Authority = "http://localhost:52718/";

            // name of the API resource
            options.Audience = "api1";

            options.RequireHttpsMetadata = false;
        });
    }

    public void Configure(IApplicationBuilder app, IHostingEnvironment env)
    {
        app.UseForwardedHeaders();
        if (env.IsDevelopment())
        {
            app.UseDeveloperExceptionPage();
        }
        app.UseIdentityServer();
        app.UseAuthentication();
        app.UseCors("AllowAll");
        app.UseMvc(routes =>
        {
            routes.MapRoute(
                name: "areas",
                template: "{area:exists}/{controller=Home}/{action=Index}/{id?}"
            );
            routes.MapRoute(
                name: "default",
                template: "{controller=Home}/{action=Index}/{id?}");
        });
    }

Now after that I put below code in my controller:

public IEnumerable<string> Get()
{
    string ip = Response.HttpContext.Connection.RemoteIpAddress.ToString();

    //https://en.wikipedia.org/wiki/Localhost
    //127.0.0.1    localhost
    //::1          localhost
    if (ip == "::1")
    {
        ip = Dns.GetHostEntry(Dns.GetHostName()).AddressList[2].ToString();
    }

    return new string[] { ip.ToString() };
 }

So, If I'm running on my localhost environment it shows my IPv4 system IP Address and If I'm running my server on azure it shows my Host Name / IP Address.

Conclusion:

I've found my answer in Mark G comment Forwarded Headers Middleware