Blog

Filter posts by the Tags of Blog section!

Filtering an area of asp.ne core mvc to an specific IP address Sunday, 21 February 2021

After moving my website to dotnet core, in order to make the admin panel more secure, I decided to filter the admin panel and restrict it to my static IPs. there are lots of ways to do that, I personally decided to handle it via middleware. Look a the following piece of code: 

  public class IPFilterMiddleware

    {

        private readonly RequestDelegate _next;

        private readonly ILogger<IPFilterMiddleware> _logger;

        private readonly string _adminSafeList;



        public IPFilterMiddleware(RequestDelegate next, ILogger<IPFilterMiddleware> logger, string adminWhiteList)

        {

            _adminSafeList = adminWhiteList;

            _next = next;

            _logger = logger;

        }



        public async Task Invoke(HttpContext context)

        {

            if (context.Request.Method != "GET")

            {

                var remoteIp = context.Connection.RemoteIpAddress;

                string[] ip = _adminSafeList.Split(',');



                var bytes = remoteIp.GetAddressBytes();

                var badIp = true;

               

                foreach (var address in ip)

                {

                    var testIp = IPAddress.Parse(address);



                    if (testIp.GetAddressBytes().SequenceEqual(bytes))

                    {

                        badIp = false;

                        break;

                    }

                }



                if (badIp)

                {

                    _logger.LogInformation($"Forbidden Request: {remoteIp}");

                    context.Response.StatusCode = (int)HttpStatusCode.Forbidden;

                    return;

                }

            }



            await _next.Invoke(context);

        }

    }


 

The middleware invokes the request and after looking at a string that contains the IPs, it returns a boolean value (badIp). Just like the ordinary way of registering the middleware, we should use it in the Configure() of  startup class:

 

    app.UseMiddleware<IPFilterMiddleware>(Configuration["ValidIp"]);


 

Obviously, we should have the ValidIp in the appsettings.json file: 


 

  "ValidIp": "127.0.0.1,192.168.1.5, 97.144.85.243"

 

And then should create a filter attribute like this: 

 

 public class IpCheckFilter : ActionFilterAttribute

    {

        private readonly ILogger _logger;



        public IpCheckFilter(ILoggerFactory loggerFactory)

        {

            _logger = loggerFactory.CreateLogger("AFilter");

        }



        public override void OnActionExecuting(ActionExecutingContext context)

        {

            _logger.LogInformation($"Remote IpAddress: {context.HttpContext.Connection.RemoteIpAddress}");

      

            base.OnActionExecuting(context);

        }

    }

 

And then register it as the scope in ConfigureService() of startup: 

 

      services.AddScoped<IpCheckFilter>();


 

That’s all. Now we can use the filter attribute in every controller of the target area: 

 

  [Authorize]

    [Area("Admin")]

    [ServiceFilter(typeof(IpCheckFilter))]

    public class ContentController : Controller

    {

        public IActionResult Index()

        {

            return View();

        }

    }


 

Cheers!

comments powered by Disqus