Giters

lontivero / Open.NAT

Lightweight and easy-to-use class library to allow port forwarding in NAT devices with UPNP and/or PMP

Geek Repo:Geek Repo

Github PK Tool:Github PK Tool

Open.NAT and ASP.NET

FreekDS opened this issue · comments

commented

The problem

I am writing a small web service application using ASP.NET. I want this web API to be visible from outside a home network (behind NAT). The problem is that the user I'm writing this program for, has no access to change his router. Creating a portforwarding rule in the router configuration is no option.

As a solution to this, I tried to use UPNP with the Open.NAT framework. Sadly I can't get this to work. I'm able to create a rule, I can see that the port is open using online tools such as canyouseeme but I cannot connect to the web api using a browser. I am 100% sure UPNP is enabled on my router.

Code

The code I'm currently using is the default weather forecast code that is generated by visual studio when creating a ASP.NET web API. I added Open.NAT from the NuGet package manager.

Then I changed the default code to the following

public static void Main(string[] args)
{
    CreatePortforwardRule().Wait();
    CreateHostBuilder(args).Build().Run();
}

static async Task CreatePortforwardRule()
{
    NatDiscoverer discoverer = new NatDiscoverer();
    CancellationTokenSource cts = new CancellationTokenSource(10000);
    var device = await discoverer.DiscoverDeviceAsync(PortMapper.Upnp, cts);
    await device.CreatePortMapAsync(new Mapping(Protocol.Tcp, 5000, 7856, "Test"));
}

When I run this application and go to canyouseeme, I get the information as shown in this image but I cannot connect to the web api using the browser. (Also tried to connect using cURL without result)

Additional things I did

In order to try to solve this, I also did the following:

  • Changed the port the application needs to run on to 5000
  • Added a firewall rule to my PC that allows inbound traffic on port 5000
  • As a sanity check, I also tried manually portforwarding on my own router which worked, but as I told before, this is no option for the user that is going to use the program.

I really hope I can find a solution. Thanks for taking time to read my question.

Link to stackoverflow post I made
https://stackoverflow.com/questions/62038952/how-to-use-open-nat-in-an-asp-net-web-api

commented

You are not providing anything that can help me to help you. Could you post the Open.NAT log file?

I would also suggest to map using the same port with a higher port, for example:

await device.CreatePortMapAsync(new Mapping(Protocol.Tcp, 15_000, 15_000, "Test"));

Once you have this just listen in that port with nc:

$ nc -l 15000

and then hit that endpoint from outside of your LAN (using your cellphone data plan, for example) and check if it was reached.

commented

Thanks for your fast reply! Where can I find the Open.NAT log file?

commented

I have followed your advice and changed the mapping entry to

await device.CreatePortMapAsync(new Mapping(Protocol.Tcp, 15000, 15000, "Test"));

I also enabled logging. The generated log contains the following:

Open.NAT Information: 0 : Start Discovery
Open.NAT Information: 0 : Searching for: UpnpSearcher
Open.NAT Information: 0 : UPnP Response: Router advertised a 'urn:schemas-upnp-org:service:WANIPConnection:2' service!!!
Open.NAT Information: 0 : Found device at: http://192.168.0.1:5000/rootDesc.xml
Open.NAT Information: 0 : 192.168.0.1:5000: Fetching service list
Open.NAT Information: 0 : Found device at: http://192.168.0.1:5000/rootDesc.xml
Open.NAT Information: 0 : 192.168.0.1:5000: Parsed services list
Open.NAT Information: 0 : 192.168.0.1:5000: Found service: urn:schemas-upnp-org:service:WANIPConnection:1
Open.NAT Information: 0 : 192.168.0.1:5000: Found upnp service at: /ctl/IPConn
Open.NAT Information: 0 : 192.168.0.1:5000: Handshake Complete
Open.NAT Information: 0 : Stop Discovery
Open.NAT Information: 0 : CreatePortMapAsync - Creating port mapping Tcp 15000 --> 192.168.0.222:15000 (Test)
Open.NAT Verbose: 0 : SOAPACTION: **AddPortMapping** url:http://192.168.0.1:5000/ctl/IPConn

info: Microsoft.Hosting.Lifetime[0]
      Now listening on: http://0.0.0.0:5000
info: Microsoft.Hosting.Lifetime[0]
      Application started. Press Ctrl+C to shut down.
info: Microsoft.Hosting.Lifetime[0]
      Hosting environment: Development
info: Microsoft.Hosting.Lifetime[0]
      Content root path: C:\Users\gebruiker\source\repos\WebApplication\WebApplication

(note: the last lines of logging are generated by my ASP.NET application)

I then used the nc -l -p 15000. When I use the canyouseeme tool to check if port 15000 is open, I get result from the nc command. But when I want to hit the endpoint using my public IP address with port 15000 from outside my home network, the request times out and I do not get result from the nc command. I temporary disabled my firewall while testing this out.

commented

Open.NAT opened the port successfully. You have verified that fact when after using https://canyouseeme.org/ you saw some output in the nc, otherwise there is no way an external service can hit a process in your machine.

I think you are probably making a mistake in your ASP application. Make sure to listen in the correct port and with the correct prefixes. It is a common mistake to listen on 127.0.0.1 instead of something more generic like http://+:15000

Anyway, there is nothing else I can help you here because clearly the port is opened.

commented

Ok, no problem, thanks for your time and help.