How to restrict access to web resources from internet but expose in intranet

user_11629052 0
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I have a website written in ASP.NET WebForms, which accesses web services that are written in ASP.NET WebAPI. For security, I closed port 8079 (web services) so that web services could only be accessed via the website, but that it would not be possible to request web services directly from the Internet. When I request a page on a website, through the Fiddler program, I see a request for a website, but I don’t see a request from a website for web services. Everything works well. But now I have made another website written in AngularJS and I want this website to also access my closed web services. Is this possible through AngularJS? Below is the request code for web services via ASP.NET website.

HttpResponseMessage response = 
client.GetAsync("http://localhost:8079/api/values/5").Result;
if (response.IsSuccessStatusCode)
{
    Task<string> data = response.Content.ReadAsStringAsync();
    result += data.Result;
}

As a result, the site(AngularJS) and ASP.Net MVC Web Application should be available on the Internet, and web services (ASP.NET WebAPI) should not be available on the Internet.

angular asp.net-web-api rest asp.net c#
3 Answers

Currently, the client accesses the web services directly, but it’s necessary to make the client access the web server and the web server access the web services

Even if you create another ASP.NET app (a kind of 'facade') that handles requests from the client, and invokes web services internally, this alone won't solve the problem:

  • If the facade accepts requests from any client and just sends them to the web services, it is not different from exposing the web services directly to the internet.

As @Andrei Dragotoniu pointed out, you have to secure your services by only accepting requests from authorized clients.

How to authorize access to web services

A common way of securing access to web services is JSON Web Token (JWT). The token contains encrypted claims that explain the identity (and maybe other aspects) of the client. Typically it works as follows:

  • A new token is generated on the server upon successful authentication of the client. The authentication can be either manual (a login form), or automatic (for example, with OAuth).
  • Once the token is generated, it is returned to the client. The client then starts attaching the token as an HTTP header to every request it sends to the web services. On every request, the web services validate the attached token.

This blogpost provides more information and examples of using JWT in C#.

API Gateways

The requirement of limiting access to web services to an internal network is not uncommon. A typical solution here is API Gateway.

(from Wikipedia) Gateway: a server that acts as an API front-end, receives API requests, enforces throttling and security policies, passes requests to the back-end service and then passes the response back to the requester. A gateway often includes a transformation engine to orchestrate and modify the requests and responses on the fly. A gateway can also provide functionality such as collecting analytics data and providing caching. The gateway can provide functionality to support authentication, authorization, security, audit and regulatory compliance.

More on API Gateways in this article. One of the most popular API Gateways is Kong.

user_45448450

"When I request a page on a website, through the Fiddler program, I see a request for a website, but I don’t see a request from a website for web services"

That statement is true in a very limited context, but the reality is much bigger than that.

The requests from a website to its own API can easily be seen by using browser tools for example ... hit F12 in any browser and look under the Network tab, this is something anyone can do to see what a website ( any website ) is doing.

You need to protect your API somehow. You can use something like OAuth2 or you could do it at server level. You can lock down a server to only accept connections from your website's IP address for example. You can also make it so that the server the API is on is completely locked down. You can lock down the API.

You just need to realize that you do have a security issue if you don't do something. The tech stack you use is irrelevant for this.

user_26112370

Even if you deploy your web service in intranet, you cannot consume the web service from client browser (Angular or JS Applications).

One possible solution could be,

  1. Deploy the web service in intranet web server.
  2. Create a proxy web service in the edge server (they are both intranet & internet facing). Proxy web service should just expose the required methods by obscuring the original web methods.
  3. Consume proxy web service from client-side applications.

Otherwise, client-side applications can never consume the intranet web services.

Optionally, if you create NodeJS, ASP.Net based web applications, it can be deployed on edge web servers that can talk to intranet web services and users (living in the internet) cannot access web services directly.

UPDATE: Moreover, based on your code above, it looks like you are trying to consume web service from .Net Runtime Managed Code (ASP.Net MVC). Well, in that case, AngularJS will ajax to your controller-action. Then controller, in the edge server, can talk to any intranet web service. AngularJS need not talk to Web Service. It is straight-forward now.

user_69280560
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