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c#processstreamfile-transfernetcat
Heinz.Benjamin
Heinz.Benjamin

Reputation: 21

Automating Netcat file transfer from C# application - Windows & Raspberry Pi

I am trying to receive a file through Netcat from a Linux based server (Raspberry Pi).

On the sender side (Raspberry Pi) I run a small Python script, that just packs up some files and sends them into the pipeline. This works great, and has been tested a lot.

On the receiver side (Windows 8.1 Pro), I use Netcat to turn the incoming stream into a file. If I do this by hand in cmd.exe, it works great:

nc -l -p <port> > C:\file.gz

My file arrives as planned. However when I try to automate this process on the receiver side with a C# script (.Net 4.5), the file simply doesn't arrive. My code looks like this:

public void StartListeningToNetcat()
        {
            Process ncProcess = new Process();
            ncProcess.StartInfo.UseShellExecute = false;
            ncProcess.StartInfo.CreateNoWindow = false;
            ncProcess.StartInfo.RedirectStandardOutput = true;
            ncProcess.StartInfo.RedirectStandardInput = true;

            ncProcess.StartInfo.FileName = "cmd.exe";
            ncProcess.StartInfo.Arguments = @"C:\...\nc -l -p <port> > C:\file.gz";
            ncProcess.Start();
        }

I am aware, that running nc through cmd.exe is a detour, but calling netcat directly like this:

            ncProcess.StartInfo.FileName = "C:\...\nc.exe";
            ncProcess.StartInfo.Arguments = @"-l -p <port> > C:\file.gz";

...returns the error: ">: forward host lookup failed: h_errno 11001: HOST_NOT_FOUND". Anyway, I wouldn't mind ignoring this error and going for the "inelegant" way to call cmd.exe.

Assuming that it could be a security measure by windows to not allow applications to write incoming files on my hard drive I tried turning of my firewall and using:

            ncProcess.StartInfo.Verb = "runas";

with no success. Could somebody point me in the right direction?

Upvotes: 0

Views: 1450

Answers (1)

Heinz.Benjamin
Heinz.Benjamin

Reputation: 21

I was just able to resolve this issue myself:

Instead of executing "cmd.exe" with the arguments to run netcat, or calling Netcat itself, I create a batch file upfront, which I can later call in my C# script.

public void StartListenToNetcat()
{
        string batchPath = CreateNetcatBatchFile();   
        Process.Start(batchPath);
}

public string CreateNetcatBatchFile()
{
        Streamwriter w = new StreamWriter("C:\runNC.bat");
        w.WriteLine("C:\...\nc -l -p 22 > C:\file.gz");
        w.Close();
        return "C:\runNC.bat";
}

Still I don't actually understand the necessity of this detour. Comments for clarifaction would be greatly appreciated.

Upvotes: 1

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