Tcl

SSH Tunnel Authenticate with a Password

Demonstrates the Chilkat SshTunnel.AuthenticatePw method, which authenticates the SSH connection with a login name and password. The first argument is the login and the second is the password. Connect first, and call BeginAccepting afterward.

Background: Password authentication is the simplest option, but the password is a secret and should never be a hard-coded literal — obtain it from an interactive prompt, an environment variable, or a secrets vault. Public-key authentication is generally preferred for the unattended, long-running services that tunnels often are.

Chilkat Tcl Downloads

Download Chilkat for Tcl

Tcl


load ./chilkat.dll

set success 0

#  Demonstrates the SshTunnel.AuthenticatePw method, which authenticates the SSH connection with
#  a login name and password.  The 1st argument is the login and the 2nd is the password.

set tunnel [new_CkSshTunnel]

#  The tunnel forwards accepted local connections to this destination through the SSH server.
CkSshTunnel_put_DestHostname $tunnel "db.internal.example.com"
CkSshTunnel_put_DestPort $tunnel 5432

#  Connect to the SSH server.  This performs the TCP/proxy connection and SSH handshake, but
#  does not authenticate yet.
set sshPort 22
set success [CkSshTunnel_Connect $tunnel "ssh.example.com" $sshPort]
if {$success == 0} then {
    puts [CkSshTunnel_lastErrorText $tunnel]
    delete_CkSshTunnel $tunnel
    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 [CkSshTunnel_AuthenticatePw $tunnel "mySshLogin" $password]
if {$success == 0} then {
    puts [CkSshTunnel_lastErrorText $tunnel]
    delete_CkSshTunnel $tunnel
    exit
}

puts "Authenticated."

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

set waitForThreadExit 1
set success [CkSshTunnel_CloseTunnel $tunnel $waitForThreadExit]
if {$success == 0} then {
    puts [CkSshTunnel_lastErrorText $tunnel]
    delete_CkSshTunnel $tunnel
    exit
}


delete_CkSshTunnel $tunnel