PureBasic

SSH Tunnel Authenticate with a Private Key

Demonstrates the Chilkat SshTunnel.AuthenticatePk method, which authenticates the SSH connection using public-key authentication. The first argument is the username and the second is an SshKey private key. The matching public key must already be installed for the account on the SSH server.

Note: The private-key path is relative to the application's current working directory. Absolute paths may also be used. Supply the path to your own key file.

Background: Public-key authentication suits tunnels especially well because they typically run unattended for long periods: the private key stays on the client, the server trusts the corresponding public key, and no reusable password crosses the wire. The SshKey object imports several formats; for an encrypted key, set its Password before importing.

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IncludeFile "CkSshTunnel.pb"
IncludeFile "CkSshKey.pb"

Procedure ChilkatExample()

    success.i = 0

    ;  Demonstrates the SshTunnel.AuthenticatePk method, which authenticates the SSH connection using
    ;  public-key authentication.  The 1st argument is the username and the 2nd is an SshKey private
    ;  key.  The matching public key must already be installed for the account on the SSH server.

    tunnel.i = CkSshTunnel::ckCreate()
    If tunnel.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    ;  The tunnel forwards accepted local connections to this destination through the SSH server.
    CkSshTunnel::setCkDestHostname(tunnel, "db.internal.example.com")
    CkSshTunnel::setCkDestPort(tunnel, 5432)

    ;  Connect to the SSH server.  This performs the TCP/proxy connection and SSH handshake, but
    ;  does not authenticate yet.
    sshPort.i = 22
    success = CkSshTunnel::ckConnect(tunnel,"ssh.example.com",sshPort)
    If success = 0
        Debug CkSshTunnel::ckLastErrorText(tunnel)
        CkSshTunnel::ckDispose(tunnel)
        ProcedureReturn
    EndIf

    ;  Load the SSH private key.  LoadText reads the file's text, which is then imported.
    privKey.i = CkSshKey::ckCreate()
    If privKey.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    keyText.s = CkSshKey::ckLoadText(privKey,"qa_data/id_rsa")
    If CkSshKey::ckLastMethodSuccess(privKey) = 0
        Debug CkSshKey::ckLastErrorText(privKey)
        CkSshTunnel::ckDispose(tunnel)
        CkSshKey::ckDispose(privKey)
        ProcedureReturn
    EndIf

    success = CkSshKey::ckFromOpenSshPrivateKey(privKey,keyText)
    If success = 0
        Debug CkSshKey::ckLastErrorText(privKey)
        CkSshTunnel::ckDispose(tunnel)
        CkSshKey::ckDispose(privKey)
        ProcedureReturn
    EndIf

    success = CkSshTunnel::ckAuthenticatePk(tunnel,"mySshLogin",privKey)
    If success = 0
        Debug CkSshTunnel::ckLastErrorText(tunnel)
        CkSshTunnel::ckDispose(tunnel)
        CkSshKey::ckDispose(privKey)
        ProcedureReturn
    EndIf

    Debug "Authenticated with a private key."

    ;  After authenticating, call BeginAccepting to start listening for local connections to forward.

    waitForThreadExit.i = 1
    success = CkSshTunnel::ckCloseTunnel(tunnel,waitForThreadExit)
    If success = 0
        Debug CkSshTunnel::ckLastErrorText(tunnel)
        CkSshTunnel::ckDispose(tunnel)
        CkSshKey::ckDispose(privKey)
        ProcedureReturn
    EndIf



    CkSshTunnel::ckDispose(tunnel)
    CkSshKey::ckDispose(privKey)


    ProcedureReturn
EndProcedure