Listener address on remote server about ftpserver

[Shinetaku]

When this issue be published to nuget?

Now remote address is not worked in docker container.

[fubar-coder]

You can use 0.0.0.0 instead.

[ArrowCase]

Interesting -- it looks like there is a difference in behavior between two apps I was using for testing, one a .NET Core console application and the other an ASP .NET Core web application (which launches the FTP server in the background). The console application starts up fine with a 0.0.0.0 binding, but the web app throws the following:

crit: FubarDev.FtpServer.FtpServer[0]
      IPv4 address 0.0.0.0 and IPv6 address ::0 are unspecified addresses
            that cannot be used as a target address.
      Parameter name: hostName
System.ArgumentException: IPv4 address 0.0.0.0 and IPv6 address ::0
      are unspecified addresses that cannot be used as a target address.
Parameter name: hostName
   at System.Net.Dns.HostResolutionBeginHelper(String hostName, Boolean justReturnParsedIp, Boolean throwOnIIPAny, AsyncCallback requestCallback, Object state)
   at System.Net.Dns.BeginGetHostAddresses(String hostNameOrAddress, AsyncCallback requestCallback, Object state)
   at System.Net.Dns.<>c.<GetHostAddressesAsync>b__25_0(String arg, AsyncCallback requestCallback, Object stateObject)
   at System.Threading.Tasks.TaskFactory`1.FromAsyncImpl[TArg1](Func`4 beginMethod, Func`2 endFunction, Action`1 endAction, TArg1 arg1, Object state, TaskCreationOptions creationOptions)
   at System.Threading.Tasks.TaskFactory`1.FromAsync[TArg1](Func`4 beginMethod, Func`2 endMethod, TArg1 arg1, Object state)
   at System.Net.Dns.GetHostAddressesAsync(String hostNameOrAddress)
   at FubarDev.FtpServer.MultiBindingTcpListener.StartAsync()
   at FubarDev.FtpServer.FtpServer.<ExecuteServerListener>b__37_0()

In any event, the web application was just being used for testing purposes, so if 0.0.0.0 works in the console app then my issue is resolved.

[ArrowCase]

0.0.0.0 does not appear to work. The application starts up successfully, but the FTP server cannot actually be reached, locally or from outside the network.

Note that I'm 100% sure that my connectivity/firewalls/etc. are set up properly. If I bind to 127.0.0.1, I can connect to the server locally, and if I bind to 10.0.0.4 I can connect locally or remotely. If I switch from 10.0.0.4 to 0.0.0.0, local and remote access both stop working.

[chaseaucoin]

So i have been having the same issue trying to get this containerized. I borught down a local copy and instead of using Dns.GetHostAddressesAsync in the MultiBindingTcpListener I added the following bits of code. Which got everything connecting up fine but now I'm having an issue with PASV beause I have to have well a well defined port range for a containers.

if(_address == "0.0.0.0") { try { Port = StartListeningAll(_port); return; } catch { Stop(); throw; } }

`
private int StartListeningAll(int port)
{
var selectedPort = port;

        var listener = new TcpListener(IPAddress.Any, selectedPort);
        listener.Start();

        if (selectedPort == 0)
        {
            selectedPort = ((IPEndPoint)listener.LocalEndpoint).Port;
        }

        _listeners.Add(listener);

        return selectedPort;
    }

`

[ArrowCase]

@fubar-coder What do you think about allowing the user to specify an IPAddress instead of a string in the FtpServerOptions? I'd be happy to submit a PR along those lines.

[chaseaucoin]

@fubar-coder What do you think about allowing the user to specify an IPAddress instead of a string in the FtpServerOptions? I'd be happy to submit a PR along those lines.

The only thing to keep in mind is backwards compatibility. Gotta be able to do either.

[fubar-coder]

I'd gladly take this PR 👍

[pnuzhdin]

@fubar-coder could you, please, release the fix to NuGet?

[rhegner]

I stumbled upon this thread while digging into the sources for trying to find a way to listen on a given port for both IPv4 and IPv6 connections.

Let me share two thoughts about the PR:

• The existing implementation allows to pass in a null/empty hostname which then defaults to IPAddress.Any:

  FtpServer/src/FubarDev.FtpServer/MultiBindingTcpListener.cs

  Line 54 in d79d406

  if (!string.IsNullOrEmpty(_address))

  The proposed change does not seem to handle that special of a null/empty address (or maybe I don't see it). For backwards compatibility I think it should.
• It looks like the recommended way to listen on a port in a dual-mode way is using TcpListener.Create(port), see https://blogs.msdn.microsoft.com/webdev/2013/01/08/dual-mode-sockets-never-create-an-ipv4-socket-again/

[fubar-coder]

I just released 2.1.1