PureBasic

SSH Tunnel Authenticate with a SecureString Password and Private Key

Demonstrates the Chilkat SshTunnel.AuthenticateSecPwPk method, which authenticates using SecureString login and password objects together with a private key. The third argument is the SshKey private key.

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: This is the SecureString form of two-factor tunnel authentication: the password is held encrypted in memory and combined with a private key for servers that require both. It is the most protective option when a deployment mandates two-factor SSH and you also want to minimize plaintext credential exposure in a long-running process.

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

Procedure ChilkatExample()

    success.i = 0

    ;  Demonstrates the SshTunnel.AuthenticateSecPwPk method, which authenticates using SecureString
    ;  login and password objects together with a private key.  The 1st argument is the username, the
    ;  2nd is the password, and the 3rd is an SshKey private key.

    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

    ;  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.s = "mySshPassword"

    ;  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

    ;  Place the login and password into SecureString objects.
    secureLogin.i = CkSecureString::ckCreate()
    If secureLogin.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    CkSecureString::ckAppend(secureLogin,"mySshLogin")
    securePassword.i = CkSecureString::ckCreate()
    If securePassword.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    CkSecureString::ckAppend(securePassword,password)

    success = CkSshTunnel::ckAuthenticateSecPwPk(tunnel,secureLogin,securePassword,privKey)
    If success = 0
        Debug CkSshTunnel::ckLastErrorText(tunnel)
        CkSshTunnel::ckDispose(tunnel)
        CkSshKey::ckDispose(privKey)
        CkSecureString::ckDispose(secureLogin)
        CkSecureString::ckDispose(securePassword)
        ProcedureReturn
    EndIf

    Debug "Authenticated."

    ;  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)
        CkSecureString::ckDispose(secureLogin)
        CkSecureString::ckDispose(securePassword)
        ProcedureReturn
    EndIf



    CkSshTunnel::ckDispose(tunnel)
    CkSshKey::ckDispose(privKey)
    CkSecureString::ckDispose(secureLogin)
    CkSecureString::ckDispose(securePassword)


    ProcedureReturn
EndProcedure