B4X

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.

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Dim success As Boolean = False

'  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.

Dim sshJump As ChilkatSsh
sshJump.Initialize("sshJump")

'  Connect and authenticate to the jump host first.
Dim port As Int = 22
success = sshJump.Connect("jump.example.com", port)
If success = False Then
    Log(sshJump.LastErrorText)
    Return
End If


'  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.
Dim password As String = "mySshPassword"

success = sshJump.AuthenticatePw("myJumpLogin", password)
If success = False Then
    Log(sshJump.LastErrorText)
    Return
End If


'  Connect to the SFTP server through the jump host.
Dim sftp As ChilkatSFtp
sftp.Initialize("sftp")
success = sftp.ConnectThroughSsh(sshJump, "sftp.internal.example.com", port)
If success = False Then
    Log(sftp.LastErrorText)
    Return
End If


'  Authenticate to the SFTP server (its own credentials), then initialize SFTP.
success = sftp.AuthenticatePw("mySshLogin", password)
If success = False Then
    Log(sftp.LastErrorText)
    Return
End If


success = sftp.InitializeSftp
If success = False Then
    Log(sftp.LastErrorText)
    Return
End If

Log("Connected to the SFTP server through the jump host.")

sftp.Disconnect
sshJump.Disconnect