Tcl

FTP over Implicit TLS (Ssl, AuthSsl, AutoFix)

Demonstrates the SSL/TLS connection-mode properties Ssl, AuthSsl, and AutoFix. Setting Ssl true selects implicit FTPS, in which TLS begins immediately after the TCP connection on port 990.

Background: FTP has two ways to add TLS: implicit (this example) starts encrypted from the first byte on a dedicated port, 990; explicit (via AuthTls) connects in the clear on port 21 and issues AUTH TLS to upgrade. Explicit is the modern standard; implicit persists mainly for legacy servers. AuthSsl is an obsolete AUTH SSL variant to avoid. AutoFix, on by default, infers the mode from the port — disable it when you set these properties explicitly so it does not override your choice.

Chilkat Tcl Downloads

Download Chilkat for Tcl

Tcl


load ./chilkat.dll

set success 0

set ftp [new_CkFtp2]

CkFtp2_put_Hostname $ftp "ftp.example.com"
CkFtp2_put_Username $ftp "myFtpLogin"

#  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.
CkFtp2_put_Password $ftp "myPassword"

#  Ssl = 1 selects IMPLICIT FTPS: TLS begins immediately after the TCP connection, before
#  the greeting.  Port 990 is conventional for implicit FTPS.  Ssl takes priority over AuthTls
#  and AuthSsl.
CkFtp2_put_Ssl $ftp 1
CkFtp2_put_Port $ftp 990

#  AuthSsl selects the legacy AUTH SSL command and is very uncommon -- use AuthTls (explicit
#  FTPS) for modern servers instead.  Left 0 here.
CkFtp2_put_AuthSsl $ftp 0

#  AutoFix (default 1) automatically adjusts Ssl/AuthTls/AuthSsl based solely on the Port
#  (21 or 990).  Disable it when setting these properties explicitly, as here.
CkFtp2_put_AutoFix $ftp 0

set success [CkFtp2_Connect $ftp]
if {$success == 0} then {
    puts [CkFtp2_lastErrorText $ftp]
    delete_CkFtp2 $ftp
    exit
}

puts "Connected using implicit FTPS."

set success [CkFtp2_Disconnect $ftp]
if {$success == 0} then {
    puts [CkFtp2_lastErrorText $ftp]
    delete_CkFtp2 $ftp
    exit
}


delete_CkFtp2 $ftp