Tcl

Connect to an SFTP Server Through a Jump Host

Demonstrates the Chilkat SFtp.ConnectThroughSsh method, which connects to an SFTP server through an already connected and authenticated Ssh object. The first argument is the jump-host Ssh object, and the second and third are the destination hostname and port.

Background: This is the "jump host" (bastion) pattern: the application connects to a reachable gateway, then tunnels onward to an SFTP server that is only accessible from inside the network. Each hop authenticates separately with its own credentials. The result is a normal SFtp object — still requiring its own authentication and InitializeSftp — that happens to be routed through the first connection.

Chilkat Tcl Downloads

Download Chilkat for Tcl

Tcl


load ./chilkat.dll

set success 0

#  Demonstrates the SFtp.ConnectThroughSsh method, which connects to an SFTP server through an
#  already connected and authenticated Ssh object (a jump host).  The 1st argument is the Ssh
#  object, and the 2nd and 3rd are the destination hostname and port.

set sshJump [new_CkSsh]

#  Connect and authenticate to the jump host first.
set port 22
set success [CkSsh_Connect $sshJump "jump.example.com" $port]
if {$success == 0} then {
    puts [CkSsh_lastErrorText $sshJump]
    delete_CkSsh $sshJump
    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 [CkSsh_AuthenticatePw $sshJump "myJumpLogin" $password]
if {$success == 0} then {
    puts [CkSsh_lastErrorText $sshJump]
    delete_CkSsh $sshJump
    exit
}

#  Connect to the SFTP server through the jump host.
set sftp [new_CkSFtp]

set success [CkSFtp_ConnectThroughSsh $sftp $sshJump "sftp.internal.example.com" $port]
if {$success == 0} then {
    puts [CkSFtp_lastErrorText $sftp]
    delete_CkSsh $sshJump
    delete_CkSFtp $sftp
    exit
}

#  Authenticate to the SFTP server (its own credentials), then initialize SFTP.
set success [CkSFtp_AuthenticatePw $sftp "mySshLogin" $password]
if {$success == 0} then {
    puts [CkSFtp_lastErrorText $sftp]
    delete_CkSsh $sshJump
    delete_CkSFtp $sftp
    exit
}

set success [CkSFtp_InitializeSftp $sftp]
if {$success == 0} then {
    puts [CkSFtp_lastErrorText $sftp]
    delete_CkSsh $sshJump
    delete_CkSFtp $sftp
    exit
}

puts "Connected to the SFTP server through the jump host."

CkSFtp_Disconnect $sftp
CkSsh_Disconnect $sshJump

delete_CkSsh $sshJump
delete_CkSFtp $sftp