How to verify if remote computer is available? - c#

I'm writing a part of a program that shall copy a batch of files from the current computer to a defined list of computers.
If these computers are not available, the code will hang for a long time trying to access them. Is there any functionallity in C# to check if the machine is available and then skip if it's not?
MFWs = File.ReadAllLines(GuiManager.MyConfigManagerConfig.MachinesList);
foreach (string MFW in MFWs)
{
if (MFW != System.Environment.MachineName)
{
String target = #"\\" + MFW + #"\D\IbSi\config\" + Path.GetFileName(ConfigFile);
String backup = #"\\" + MFW + #"\D\IbSi\userdata\" + Path.GetFileName(ConfigFile);
try
{
File.Copy(source, target, true);
File.Copy(source, backup, true);
}
catch (Exception ex)
{
Manager.SendMessage("Failed to copy " + Path.GetFileName(ConfigFile) + " to " + MFW + "\n" + ex.Message);
}
}
}

You could ping the computer before starting the copy (taken from this answer):
using System.Net.NetworkInformation;
public static bool IsHostAvailable(string nameOrAddress)
{
bool pingable = false;
Ping pinger = new Ping();
try
{
PingReply reply = pinger.Send(nameOrAddress);
pingable = reply.Status == IPStatus.Success;
}
catch (PingException)
{
// Discard PingExceptions and return false;
}
return pingable;
}
As noted in the comments you need to make sure the firewall on the servers is open for pings (ICMP echo requests)

Related

Console.WriteLine is blank

I have a strange problem. I wrote a .net 2.0 console application running on Windows Server 2008 R2 that processes a file that's passed in via args When I run it by hand and pass in a file, I don't get an output. Nothing. No errors or exception of any kind. Event log is clear. I would expect that I get some output from the exe. I also have a Console.WriteLine in my catch statement. But again, no output whatsoever. Any ideas why?
using System;
using System.Collections.Generic;
//using System.Linq;
using System.Text;
using System.IO;
namespace RTDXCentralFileTransmit
{
class Program
{
static void Main(string[] args)
{
try
{
if (args.Length < 1)
{
Console.WriteLine("File name is required");
logit("File name is required");
return;
}
string filename = args[0];
Console.WriteLine("Now doing " + filename);
logit("Now doing " + filename);
if (!File.Exists(filename))
{
Console.WriteLine("File " + filename + " does not exists. Exiting.");
logit("File " + filename + " does not exists. Exiting.");
File.WriteAllText("Error.txt", "File " + filename + " does not exists. Exiting.");
return;
}
string fileplain = File.ReadAllText(filename);
string file64 = EncodeTo64(fileplain);
if (string.IsNullOrEmpty(file64))
{
Console.WriteLine("File " + filename + " is empty. Exiting");
logit("File " + filename + " is empty. Exiting");
File.WriteAllText("Error.txt", "File " + filename + " is empty. Exiting");
return;
}
FileInfo fi = new FileInfo(filename);
com.xxxxxxxxxxxxxxxxxx.api.Dispatch dis = new com.xxxxxxxxxxxxxxxx.api.Dispatch();
com.xxxxxxxxxxxx.api.FunnelResult fr = dis.Funnel(file64, fi.Name);
if (fr.Success)
{
Console.WriteLine("Success! " + fr.Result);
logit("Success! Response from the server: " + fr.Result);
File.WriteAllText("Success.txt", fr.Result);
return;
} else
{
Console.WriteLine("Failed!! " + fr.Result);
logit("Failed!! " + fr.Result);
File.WriteAllText("Error.txt", "Transmission Failed! " + fr.Result);
}
logit("Exiting for " + filename);
Environment.Exit(0);
} catch (Exception e)
{
Console.WriteLine("Error. " + e.ToString());
return;
}
}
static void logit (string s)
{
File.AppendAllText("FileTransmit.log",DateTime.Now.ToString() + ":" + s + Environment.NewLine);
}
static public string EncodeTo64(string toEncode)
{
byte[] toEncodeAsBytes
= System.Text.ASCIIEncoding.ASCII.GetBytes(toEncode);
string returnValue
= System.Convert.ToBase64String(toEncodeAsBytes);
return returnValue;
}
}
}
I found it. The issue was between the chair and the computer.
The project that I cloned, even though it had tons of Console.WriteLine, it was actually was being built as Windows Application. That explains why we have no output for the Console.WriteLine.
Since it was being build as windows application, the console doesn't wait for the program to finish. It returns right away - which totally threw me off seeing that many console.writelines. However, the program is still running and, with a large file, it takes a while to post it to the remote server. After waiting a minute or two all of 10 MB file was transmitted successfully as it was indicated in the logs.

Copying a file that is a virus caused my program to terminate

I have made a tool that will copy files from a source to a destination. However during the copy, the software came across a virus that was flagged by the anti-virus software (Symantec).
The anti-virus then caused my software to close down, and quarantine the program as a "dropper".
Is there anyway I can gracefully handle this scenario, rather than shutting down my program completely?
I appreciate that the action was the result of the anti-virus, but is there anything I can do to help the situation? For example, Robocopy does not just terminate when it comes across a virus.
Here is my copy code;
void CopyFileExactly(CopyParameterBundle cpb, bool overwrite)
{
string CTP = "", CFP = "";
CFP = cpb.SourcePath;
if (cpb.RenameFile)
CTP = cpb.DestPath ;
else
CTP = cpb.DestPath;
//Check firstly if the file to copy exists
if (!File.Exists(CFP))
{
throw new FileNotFoundException();
}
//Check if destination file exists
//If it does, make it not read only so we can update MAC times
if (File.Exists(CTP))
{
var target = GetFile(CTP);//new FileInfo(CTP);
if (target.IsReadOnly)
target.IsReadOnly = false;
}
var origin = GetFile(CFP);//new FileInfo(CFP);
GetFile(CTP).Directory.Create();
//(new FileInfo(CTP)).Directory.Create();
origin.CopyTo(CTP, (overwrite ? true : false));
if (!File.Exists(CTP))
{
throw new FileNotFoundException("Destination file not found!");
}
var destination = GetFile(CTP);//new FileInfo(CTP);
if (destination.IsReadOnly)
{
destination.IsReadOnly = false;
destination.CreationTime = origin.CreationTime;
destination.LastWriteTime = origin.LastWriteTime;
destination.LastAccessTime = origin.LastAccessTime;
destination.IsReadOnly = true;
}
else
{
destination.CreationTime = origin.CreationTime;
destination.LastWriteTime = origin.LastWriteTime;
destination.LastAccessTime = origin.LastAccessTime;
}
if (performMD5Check)
{
var md5Check = compareFileMD5(CFP, CTP);
cpb.srcMD5Hash = md5Check.Item2;
cpb.dstMD5Hash = md5Check.Item3;
if (!md5Check.Item1)
throw new MD5MismatchException("MD5 Hashes do NOT match!");
}
}
The calling code;
void BeginCopy(int DegreeOfParallelism, int retryCount, int retryDelay)
{
object _lock;
//Setup cancellation token
po.CancellationToken = cts.Token;
//Set max number of threads
po.MaxDegreeOfParallelism = DegreeOfParallelism;
//Exceptio logging queue
var exceptions = new ConcurrentQueue<Exception>();
var completeItems = new ConcurrentQueue<CopyParameterBundle>();
var erroredItems = new ConcurrentQueue<CopyParameterBundle>();
//Logger logger = new Logger(sLogPath);
//logger.Write("Starting copy");
Task.Factory.StartNew(() =>
{
Parallel.ForEach(CopyParameters,
po,
(i, loopState, localSum) =>
{
localSum = retryCount;
do
{
try
{
//Go off and attempt to copy the file
DoWork(i);
//Incrememt total count by 1 if successfull
i.copyResults.TransferTime = DateTime.Now;
i.copyResults.TransferComplete = true;
completeItems.Enqueue(i);
//logger.Write("Copied file from: " + i.SourcePath + "\\" + i.SourceFile + " => " + i.DestPath + "\\" + i.SourceFile);
break;
}
catch (Exception ex)
{
//this.richTextBox1.AppendText("[-] Exception on: " + i.SourcePath + "\\" + i.SourceFile + " => " + ex.Message.ToString() + System.Environment.NewLine);
//Exception was thrown when attempting to copy file
if (localSum == 0)
{
//Given up attempting to copy. Log exception in exception queue
exceptions.Enqueue(ex);
this.SetErrorText(exceptions.Count());
//Write the error to the screen
this.Invoke((MethodInvoker)delegate
{
this.richTextBox1.AppendText("[-] Exception on: " + i.SourcePath + "\\" + i.SourceFile + " => " + ex.Message.ToString() + System.Environment.NewLine);
i.copyResults.TransferComplete = false;
i.copyResults.TransferTime = DateTime.Now;
i.copyResults.exceptionMsg = ex;
erroredItems.Enqueue(i);
//logger.Write("ERROR COPYING FILE FROM : " + i.SourcePath + "\\" + i.SourceFile + " => " + i.DestPath + "\\" + i.SourceFile + " => " + ex.Message.ToString() + " => " + ex.Source);
});
}
//Sleep for specified time before trying again
Thread.Sleep(retryDelay);
localSum--;
}
//Attempt to Repeat X times
} while (localSum >= 0);
//Check cancellation token
po.CancellationToken.ThrowIfCancellationRequested();
Interlocked.Increment(ref TotalProcessed);
this.SetProcessedText(TotalProcessed);
//Update Progress Bar
this.Invoke((MethodInvoker)delegate
{
this.progressBar1.Value = (TotalProcessed);
});
});
//aTimer.Stop();
this.Invoke((MethodInvoker)delegate
{
this.label9.Text = "Process: Writing Log";
});
WriteLog(sLogPath, completeItems, erroredItems);
this.Invoke((MethodInvoker)delegate
{
this.label9.Text = "Process: Done!";
});
if (exceptions.Count == 0)
MessageBox.Show("Done!");
else
MessageBox.Show("Done with errors!");
EnableDisableButton(this.button2, true);
EnableDisableButton(this.button4, false);
});
}
What happened is most likely that the antivirus was aware of the virus file, so when it detected that a change in the file system (moving the file) occurred, it terminated the program because by moving the virus to a different location in your computer, it could cause problems (since it's a virus). It was flagged as dropper, basically a type of program that is designed to install the virus.
Edit: i forgot to mention that to solve the problem you will most likely need to license your program.

SSH connection remained open after debug error

So i am making an application which can open connections to remote devices and execute different commands. So yesterday before i left work i was debugging when i got an error. But as my application ignored it and proceeded and having not enough time to fix it immedietly i decided to do it today. When i wanted to make connection with my program again it said it couldn't authenticate (note* the parameters did not change).
So i did some checks to determine the problem, after logging in on the server and running netstat i found out that there was an active connection to port 22, which originated from my application.
Somehow the connection did not show up in my SSH manager until i rebooted it TWICE.
So to prevent things like this in a production environment, how do i prevent things like this.
my Program.cs
class Program
{
static void Main(string[] args)
{
var ip="";
var port=0;
var user="";
var pwd="";
var cmdCommand="";
ConnectionInfo ConnNfo;
ExecuteCommand exec = new ExecuteCommand();
SSHConnection sshConn = new SSHConnection();
if (args.Length > 0)
{
ip = args[0];
port = Convert.ToInt32(args[1]);
user = args[2];
pwd = args[3];
cmdCommand = args[4];
ConnNfo = sshConn.makeSSHConnection(ip, port, user, pwd);
exec.executeCMDbySSH(ConnNfo, cmdCommand);
}
else {
try
{
XMLParser parser = new XMLParser();
List<List<string>> configVars = parser.createReader("C:\\Users\\myusername\\Desktop\\config.xml");
Console.WriteLine("this is from program.cs");
//iterate through array
for (int i = 0; i < configVars[0].Count; i++)
{
if ((configVars[0][i].ToString() == "device" && configVars[1][i].ToString() == "device") && (configVars[0][i + 6].ToString() == "device" && configVars[1][i + 6].ToString() == "no value"))
{
string ipAdress = configVars[1][i + 1].ToString();
int portNum = Convert.ToInt32(configVars[1][i + 2]);
string username = configVars[1][i + 3].ToString();
string passwd = configVars[1][i + 4].ToString();
string command = configVars[1][i + 5].ToString();
Console.WriteLine("making connection with:");
Console.WriteLine(ipAdress + " " + portNum + " " + username + " " + passwd + " " + command);
ConnNfo = sshConn.makeSSHConnection(ipAdress, portNum, username, passwd);
Console.WriteLine("executing command: ");
exec.executeCMDbySSH(ConnNfo, command);
}
}
}
catch (Exception e) { Console.WriteLine("Error occurred: " + e); }
}
Console.WriteLine("press a key to exit");
Console.ReadKey();
}
}
my executeCommand class:
public class ExecuteCommand
{
public ExecuteCommand()
{
}
public void executeCMDbySSH(ConnectionInfo ConnNfo, string cmdCommand )
{
try
{
using (var sshclient = new SshClient(ConnNfo))
{
//the error appeared here at sshclient.Connect();
sshclient.Connect();
using (var cmd = sshclient.CreateCommand(cmdCommand))
{
cmd.Execute();
Console.WriteLine("Command>" + cmd.CommandText);
Console.WriteLine(cmd.Result);
Console.WriteLine("Return Value = {0}", cmd.ExitStatus);
}
sshclient.Disconnect();
}
}
catch (Exception e) { Console.WriteLine("Error occurred: " + e); }
}
}
and my class where i make conenction:
public class SSHConnection
{
public SSHConnection() { }
public ConnectionInfo makeSSHConnection(string ipAdress, int port, string user, string pwd)
{
ConnectionInfo ConnNfo = new ConnectionInfo(ipAdress, port, user,
new AuthenticationMethod[]{
// Pasword based Authentication
new PasswordAuthenticationMethod(user,pwd),
}
);
return ConnNfo;
}
}
Note* i have not included my XMLParser class because it is not relevant to the question, nor does it have any connections regarding SSH in general.
EDIT
i found out i had compiled the application and it was running in the commandline. Turns out there is no error with the code

Response.Buffer doesn't work

I'm working on a windows form in which I ping a host.
For some reason, I cant get Response.Buffer to work. I tried using HttpContext.Current, and I also double checked I added a reference to both System.Web, and System.Net.NetworkInformation.
Here is the code :
Ping p = new Ping();
PingReply r;
String s = UserInput;
r = p.Send(s);
HttpContext.Current.Response.Buffer = false;
if (r.Status == IPStatus.Success)
{
string got = "Ping to " + s.ToString() + "[" + r.Address.ToString() + "] successful - " + r.Buffer.Length.ToString() + " bytes in " + r.RoundtripTime.ToString() + " ms." + "\n";
string ToSave = ToSave + got;
}
What you are trying to do does not make sense. Pinging a host is to check whether it is alive, not sending / receiving data, what I think you are trying to do.
When you want to communicate between two clients, then TcpClient is probably what you need. Take a look at the docs and demo here.
When just trying to check connectivity, try this:
Ping p = new Ping();
PingReply reply = p.Send("www.contoso.com");
if (reply.Status == IPStatus.Success)
{
...
}

Sending files from Client to Server

I am trying to send multiple files to a server ever 2 seconds and after the file is sent it is deleted and the program is restarted as to again generate the file which needs again to be sent to server.
But it works till the time the server is online...In case the sever is restarted all the program functions will work fine but when this function is invoked it keeps on displaying "No connection could be made because the target machine actively refused it" no matter even when the server comes online in between..
private void sendfile()
{
timer.Stop();
RegistryKey theLocalMachine = Registry.LocalMachine;
RegistryKey theSystem2 = theLocalMachine.OpenSubKey(#"SOFTWARE\\NetworkUsagemonitoring\\", true);
RegistryKey interfacekey4 = theSystem2.OpenSubKey("Usagerecorder", true);
string serverno = interfacekey4.GetValue("serverno").ToString();
for (int i = 0; i < netarr1.Length; i++)
{
for (int j = 0; j < netarr2.Length; j++)
{
if (netarr1[i].Name == netarr2[j])
{
if (recorded[j] == 1)
{
try
{
IPEndPoint ipEnd = new IPEndPoint(IPAddress.Parse(serverno), 5656);
Socket clientSock = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.IP);
if (File.Exists(#"C:\" + netarr1[i].Name + "_record.xml"))
{
fileName = (#"C:\" + netarr1[i].Name + "_record.xml");
fileName = fileName.Replace("\\", "/");
while (fileName.IndexOf("/") > -1)
{
filePath += fileName.Substring(0, fileName.IndexOf("/") + 1);
fileName = fileName.Substring(fileName.IndexOf("/") + 1);
}
byte[] fileNameByte = Encoding.ASCII.GetBytes(fileName);
if (fileNameByte.Length > 850 * 1024)
{
return;
}
byte[] fileData = File.ReadAllBytes(filePath + fileName);
byte[] clientData = new byte[4 + fileNameByte.Length + fileData.Length];
byte[] fileNameLen = BitConverter.GetBytes(fileNameByte.Length);
fileNameLen.CopyTo(clientData, 0);
fileNameByte.CopyTo(clientData, 4);
fileData.CopyTo(clientData, 4 + fileNameByte.Length);
clientSock.Connect(ipEnd);
clientSock.Send(clientData);
clientSock.Close();
recorded[j] = 0;
File.Delete(#"C:\" + netarr1[i].Name + "_record.xml");
}
else
{
UpdateNetwork_Interface();
}
}
catch (Exception ex)
{
LogEvent("No connection could be made because the target machine actively refused it", EventLogEntryType.Information);
break;
}
finally
{
j++;
}
}
else
{
UpdateNetwork_Interface();
}
}
}
}
}
What i want is of the server goes offline or "No connection could be made because the target machine actively refused it" is displayed...the program should continue with the loop and move unhindered until server comes online and the updated file will be sent to the server.
Well, you're exception handling is faulty. You are catching (Exception ex) and printing out the error message you quoted. It's entirely possible that the ACTUALL exception has to do with the files you are writing and erasing. perhaps some files failed to erase or be opened.
Looking at the code, i suspect the problem is that you're never actually closing the socket if there is an exception.
You should add the following to the finally clause.
if (clientSocket!=null)
clientSocket.Close();
And you should print out the actual exception message to the error log so you know what's really going on when an error occurs.

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