Visual Basic 6.0

Check the SSH Connection (IsConnected)

Demonstrates how to check whether the connection to the SSH server still exists. The IsConnected property is checked first, and SendIgnore is then used to confirm the link for certain.

Background: These checks differ in strength. IsConnected simply reports the state the object already knows and involves no network activity, so it can stay true after a silent network failure the operating system has not yet noticed. SendIgnore sends an SSH IGNORE message — discarded by the peer by design — which exercises the real write path and is therefore much stronger evidence the link is usable. CheckConnection sits between the two, peeking at the socket without sending anything.

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Visual Basic 6.0

Dim success As Long
success = 0

'  Demonstrates how to check whether the connection to the SSH server still exists.

Dim ssh As New ChilkatSsh

Dim port As Long
port = 22
success = ssh.Connect("ssh.example.com",port)
If (success = 0) Then
    Debug.Print ssh.LastErrorText
    Exit Sub
End If

'  IsConnected reports the state already known to the Ssh object.  It does not perform a
'  network round trip.
Dim connected As Long
connected = ssh.IsConnected
If (connected) Then
    '  Verify for certain by sending an SSH IGNORE message, which exercises the actual write
    '  path.  The server sends no reply, but a successful send proves the link is writable.
    connected = ssh.SendIgnore()
End If

Debug.Print "connected = " & connected

ssh.Disconnect 

'  After disconnecting, the object reports that it is no longer connected.
connected = ssh.IsConnected
Debug.Print "connected = " & connected