CkPython

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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import sys
import chilkat

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 = chilkat.CkSsh()

sshPort = 22
success = ssh.Connect("ssh.example.com",sshPort)
if (success == False):
    print(ssh.lastErrorText())
    sys.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 == False):
    print(ssh.lastErrorText())
    sys.exit()

#  Open a session channel.  A negative return value indicates failure.
channelNum = ssh.OpenSessionChannel()
if (channelNum < 0):
    print(ssh.lastErrorText())
    sys.exit()

if (ssh.ChannelIsOpen(channelNum)):
    print("The channel is open.")
else:
    print("The channel is not open.")

#  Send CLOSE, which immediately marks the channel locally closed.
success = ssh.ChannelSendClose(channelNum)
if (success == False):
    print(ssh.lastErrorText())
    sys.exit()

if (ssh.ChannelIsOpen(channelNum)):
    print("Still open.")
else:
    print("The channel is now closed.")

ssh.Disconnect()