I'm trying to asynchronously scan TCP ports. Since the open ports take just a few hundredths of milliseconds to complete they're fine, but when ports are closed I have to wait for the response.
So what happens is that I run the app and almost right away I see the port 80 to be open. Then I must wait like half a minute for all the other ports to get scanned.
EDIT. plus I would like to show the respond as it happens, with out waiting for other ports to be checked.
How to make this faster?
private void btnStart_Click(object sender, EventArgs e)
{
for (int port = 79; port < 90; port++)
{
ScanPort(port);
}
}
private void ScanPort(int port)
{
TcpClient client = new TcpClient();
client.BeginConnect(IPAddress.Parse("74.125.226.84"), port, new AsyncCallback(CallBack), client);
}
private void CallBack(IAsyncResult result)
{
bool connected = false;
using (TcpClient client = (TcpClient)result.AsyncState)
{
try
{
client.EndConnect(result);
connected = client.Connected;
}
catch (SocketException)
{
}
}
if (connected)
{
this.Invoke((MethodInvoker)delegate
{
txtDisplay.Text += "open2" + Environment.NewLine;
});
}
else
{
this.Invoke((MethodInvoker)delegate
{
txtDisplay.Text += "closed2" + Environment.NewLine;
});
}
}
You can occasionally improve Nmap scan times by increasing your available bandwidth or CPU power. This may be done either by installing a new data line or CPU, or by halting concurrently running applications which compete for these resources.
Typical scan times A default full scan of 2000-4000 assets takes 2-3 days.
You can use the WaitHandle BeginConnect returns to only wait so long.
using (var tcp = new TcpClient())
{
var ar = tcp.BeginConnect(host, port, null, null);
using (ar.AsyncWaitHandle)
{
//Wait 2 seconds for connection.
if (ar.AsyncWaitHandle.WaitOne(2000, false))
{
try
{
tcp.EndConnect(ar);
//Connect was successful.
}
catch
{
//EndConnect threw an exception.
//Most likely means the server refused the connection.
}
}
else
{
//Connection timed out.
}
}
}
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