VB.NET

SSH Parallel Remote Commands on Multiple Servers

See more SSH Examples

Shows how to execute a command in parallel on multiple servers. VB.NET

Dim success As Boolean = False

' This example requires the Chilkat API to have been previously unlocked.
' See Global Unlock Sample for sample code.

' Executing a command on multiple servers simultaneously is straightforward.
' It's just a matter of using one SSH object per server..
Dim ssh1 As New Chilkat.Ssh
Dim ssh2 As New Chilkat.Ssh
Dim ssh3 As New Chilkat.Ssh

Dim port As Integer = 22
success = ssh1.Connect("ssh-server1.com",port)
If (success <> True) Then
    Debug.WriteLine(ssh1.LastErrorText)
    Exit Sub
End If


' Authenticate using login/password:
success = ssh1.AuthenticatePw("sshLogin1","sshPassword1")
If (success <> True) Then
    Debug.WriteLine(ssh1.LastErrorText)
    Exit Sub
End If


' Connect and authenticate with 2 more servers.
' For brevity, the success/failure won't be checked...
success = ssh2.Connect("ssh-server2.com",port)
success = ssh2.AuthenticatePw("sshLogin2","sshPassword2")
success = ssh3.Connect("ssh-server3.com",port)
success = ssh3.AuthenticatePw("sshLogin3","sshPassword3")

' Note: If we wanted, we could've used ConnectAsync and AuthenticatePwAsync
' to do the connecting and authenticating in parallel...

' The command to be run on each SSH server will sleep for 5 seconds,
' and then show the current system date/time.
Dim cmd As String = "sleep 5; date"

' Start each command
Dim ssh1Channel As Integer = ssh1.QuickCmdSend(cmd)
If (ssh1Channel < 0) Then
    Debug.WriteLine(ssh1.LastErrorText)
    Exit Sub
End If

' For brevity, we're not checking the return values here:
Dim ssh2Channel As Integer = ssh2.QuickCmdSend(cmd)
Dim ssh3Channel As Integer = ssh3.QuickCmdSend(cmd)

' OK, at this point the command is running simultaneously on each server.

' Now collect the results of each command.
Dim pollTimeoutMs As Integer = 50
Dim numFinished As Integer = 0
Dim channel As Integer
' Note: You would rewrite this code to use arrays.
Dim ssh1Finished As Boolean = False
Dim ssh2Finished As Boolean = False
Dim ssh3Finished As Boolean = False
While numFinished < 3
    ' Check to see if anything has finished.
    ' QuickCmdCheck returns -1 if there are no errors and nothing else finished
    ' QuickCmdCheck returns -2 if there was an error (such as a lost connection)
    ' QuickCmdCheck returns a channel number if a channel finished.
    If (ssh1Finished <> True) Then
        channel = ssh1.QuickCmdCheck(pollTimeoutMs)
        If (channel = -2) Then
            Debug.WriteLine(ssh1.LastErrorText)
            Exit Sub
        End If

        If (channel = ssh1Channel) Then
            Debug.WriteLine("---- ssh1 channel " & channel & " finished ----")
            Debug.WriteLine(ssh1.GetReceivedText(channel,"ansi"))
            numFinished = numFinished + 1
            ssh1Finished = True
        End If

    End If

    If (ssh2Finished <> True) Then
        channel = ssh2.QuickCmdCheck(pollTimeoutMs)
        If (channel = -2) Then
            Debug.WriteLine(ssh2.LastErrorText)
            Exit Sub
        End If

        If (channel = ssh2Channel) Then
            Debug.WriteLine("---- ssh2 channel " & channel & " finished ----")
            Debug.WriteLine(ssh2.GetReceivedText(channel,"ansi"))
            numFinished = numFinished + 1
            ssh2Finished = True
        End If

    End If

    If (ssh3Finished <> True) Then
        channel = ssh3.QuickCmdCheck(pollTimeoutMs)
        If (channel = -2) Then
            Debug.WriteLine(ssh3.LastErrorText)
            Exit Sub
        End If

        If (channel = ssh3Channel) Then
            Debug.WriteLine("---- ssh3 channel " & channel & " finished ----")
            Debug.WriteLine(ssh3.GetReceivedText(channel,"ansi"))
            numFinished = numFinished + 1
            ssh3Finished = True
        End If

    End If


End While

' --------------
' Sample output:

' 	---- ssh2 channel 101 finished ----
' 	Fri Dec 23 00:25:48 UTC 2016
' 
' 	---- ssh3 channel 102 finished ----
' 	Thu Dec 22 18:25:12 CST 2016
' 
' 	---- ssh1 channel 100 finished ----
' 	Thu Dec 22 18:25:48 CST 2016