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Check Whether an SSH Channel is Open

Demonstrates the Chilkat Ssh.ChannelIsOpen method, which reports whether a channel number identifies a channel Chilkat currently considers open for application I/O. The only argument is the channel number. This example checks the channel before and after sending CLOSE.

Background: Because one SSH connection can carry many channels with independent lifetimes, code that manages several needs a way to ask whether a given one is still usable. This returns false for invalid or nonexistent channel numbers, after a local Disconnect, once remote closure is processed, and immediately after ChannelSendClose — which marks the channel locally closed without waiting for the remote side.

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Add-Type -Path "C:\chilkat\ChilkatDotNet47-x64\ChilkatDotNet47.dll"

$success = $false

#  Demonstrates the Ssh.ChannelIsOpen method, which reports whether a channel number identifies
#  a channel Chilkat currently considers open for application I/O.  The only argument is the
#  channel number.

$ssh = New-Object Chilkat.Ssh

$sshPort = 22
$success = $ssh.Connect("ssh.example.com",$sshPort)
if ($success -eq $false) {
    $($ssh.LastErrorText)
    exit
}

#  Normally you would not hard-code the password in source.  You should instead obtain it
#  from an interactive prompt, environment variable, or a secrets vault.
$password = "mySshPassword"

$success = $ssh.AuthenticatePw("mySshLogin",$password)
if ($success -eq $false) {
    $($ssh.LastErrorText)
    exit
}

#  Open a session channel.  A negative return value indicates failure.
$channelNum = $ssh.OpenSessionChannel()
if ($channelNum -lt 0) {
    $($ssh.LastErrorText)
    exit
}

if ($ssh.ChannelIsOpen($channelNum)) {
    $("The channel is open.")
}
else {
    $("The channel is not open.")
}

#  Send CLOSE, which immediately marks the channel locally closed.
$success = $ssh.ChannelSendClose($channelNum)
if ($success -eq $false) {
    $($ssh.LastErrorText)
    exit
}

if ($ssh.ChannelIsOpen($channelNum)) {
    $("Still open.")
}
else {
    $("The channel is now closed.")
}

$ssh.Disconnect()