Tcl

SSH Tunnel Per-Client Logging and Client Identifier

Demonstrates the ClientLogDir and ClientIdentifier properties. When ClientLogDir is set, a separate log file is created for each tunnel client; ClientIdentifier is the SSH client-identification string sent during the handshake.

Note: The log paths are relative to the application's current working directory. Absolute paths may also be used.

Background: When many clients share one tunnel, a single combined log is hard to follow, so ClientLogDir gives each connection its own file — the fastest way to diagnose one misbehaving client. ClientIdentifier sets the version string the server sees; overriding the default is occasionally needed for compatibility with servers that key behavior off the client identification, or simply to label your application in server logs.

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Tcl


load ./chilkat.dll

set success 0

#  Demonstrates the SshTunnel per-client logging properties ClientLogDir and ClientIdentifier.

set tunnel [new_CkSshTunnel]

#  When ClientLogDir is set, a separate log file is created for each tunnel client in this
#  directory, which is useful for troubleshooting individual connections.
CkSshTunnel_put_ClientLogDir $tunnel "qa_output/client_logs"

#  The SSH client-identification string sent to the SSH server during the handshake.
CkSshTunnel_put_ClientIdentifier $tunnel "SSH-2.0-MyTunnelApp_1.0"

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 running; each client is logged in [CkSshTunnel_clientLogDir $tunnel]"

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


delete_CkSshTunnel $tunnel