Tcl

Send an SSH IGNORE Message over SFTP

Demonstrates the Chilkat SFtp.SendIgnore method, which sends an SSH IGNORE message. It takes no arguments. The server sends no reply, but a successful send helps confirm the connection is still writable. No SFTP file handle is required.

Background: The SSH IGNORE message is discarded by the peer by design; its value is as a lightweight keep-alive or liveness probe. During a long-idle SFTP session — for instance while waiting between scheduled transfers — a periodic SendIgnore both keeps the connection from being dropped for inactivity and proves the link is still usable, without touching any file.

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Tcl


load ./chilkat.dll

set success 0

#  Demonstrates the SFtp.SendIgnore method, which sends an SSH IGNORE message.  It takes no
#  arguments.  The server sends no reply, but a successful send helps confirm the connection is
#  still writable.  No SFTP file handle is required.

set sftp [new_CkSFtp]

#  Step 1: Connect the SSH transport.  Port 22 is the usual port.
set port 22
set success [CkSFtp_Connect $sftp "sftp.example.com" $port]
if {$success == 0} then {
    puts [CkSFtp_lastErrorText $sftp]
    delete_CkSFtp $sftp
    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.
set password "mySshPassword"

set success [CkSFtp_AuthenticatePw $sftp "mySshLogin" $password]
if {$success == 0} then {
    puts [CkSFtp_lastErrorText $sftp]
    delete_CkSFtp $sftp
    exit
}

#  Step 3: Open the SFTP subsystem.  This must be done after authentication and before any
#  file or directory operations.
set success [CkSFtp_InitializeSftp $sftp]
if {$success == 0} then {
    puts [CkSFtp_lastErrorText $sftp]
    delete_CkSFtp $sftp
    exit
}

#  Send an IGNORE message to verify the connection is still writable.
set success [CkSFtp_SendIgnore $sftp]
if {$success == 0} then {
    puts [CkSFtp_lastErrorText $sftp]
    delete_CkSFtp $sftp
    exit
}

puts "IGNORE message sent."

CkSFtp_Disconnect $sftp

delete_CkSFtp $sftp