Tcl

SSH Tunnel Uncommon Options

Demonstrates the UncommonOptions property, which enables optional behavior for uncommon requirements. The default is an empty string; provide a comma-separated list of keywords to enable more than one option. Available keywords are listed in the reference documentation.

Background: This is a catch-all for narrow workarounds that do not warrant their own properties — forcing a specific signature algorithm, disabling the periodic keep-alive, removing weak MACs, bypassing a VPN on Android, and so on. Most applications never set it. When you do, it is usually to satisfy a particular server's quirk or a specific security requirement, and the exact keyword matters, so consult the documented list rather than guessing.

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Tcl


load ./chilkat.dll

set success 0

#  Demonstrates the SshTunnel.UncommonOptions property, which enables optional behavior for
#  uncommon requirements.  The default is an empty string, appropriate for most applications.
#  Provide a comma-separated list of keywords to enable more than one option.

set tunnel [new_CkSshTunnel]

#  For example, disable the periodic keep-alive ignore message and remove weak MAC algorithms
#  from those offered.  Available keywords are listed in the reference documentation.
CkSshTunnel_put_UncommonOptions $tunnel "NoKeepAliveIgnoreMsg,no-weak-mac-algs"

CkSshTunnel_put_DestHostname $tunnel "db.internal.example.com"
CkSshTunnel_put_DestPort $tunnel 5432

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
}

set listenPort 1080
set success [CkSshTunnel_BeginAccepting $tunnel $listenPort]
if {$success == 0} then {
    puts [CkSshTunnel_lastErrorText $tunnel]
    delete_CkSshTunnel $tunnel
    exit
}

puts "Tunnel established."

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


delete_CkSshTunnel $tunnel