Tcl

Request SSH X11 Forwarding

Demonstrates the Chilkat Ssh.SendReqX11Forwarding method, which sends an X11-forwarding request on a session channel. The arguments are the channel number, whether forwarding is limited to a single connection, and the X11 authentication protocol, cookie, and screen number.

Background: X11 forwarding lets a graphical program running on the remote host display its window on your local machine, tunneled over SSH. This is a low-level method that only sends the protocol request — your application is still responsible for the local X server side of the arrangement. The authentication cookie guards the forwarded display, so it should be a freshly generated value rather than a fixed constant.

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Tcl


load ./chilkat.dll

set success 0

#  Demonstrates the Ssh.SendReqX11Forwarding method, which sends an SSH X11-forwarding request
#  on a session channel.  The 1st argument is the channel number, the 2nd limits forwarding to a
#  single connection, and the 3rd through 5th supply the X11 authentication protocol, cookie,
#  and screen number.

set ssh [new_CkSsh]

set sshPort 22
set success [CkSsh_Connect $ssh "ssh.example.com" $sshPort]
if {$success == 0} then {
    puts [CkSsh_lastErrorText $ssh]
    delete_CkSsh $ssh
    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 [CkSsh_AuthenticatePw $ssh "mySshLogin" $password]
if {$success == 0} then {
    puts [CkSsh_lastErrorText $ssh]
    delete_CkSsh $ssh
    exit
}

#  Open a session channel.  A negative return value indicates failure.
set channelNum [CkSsh_OpenSessionChannel $ssh]
if {$channelNum < 0} then {
    puts [CkSsh_lastErrorText $ssh]
    delete_CkSsh $ssh
    exit
}

#  Request X11 forwarding.  Named variables make each argument's meaning clear.
set singleConnection 0
set authProt "MIT-MAGIC-COOKIE-1"
set authCookie "d92f5e1a7c8b4306af17c2e5b9d43081"
set screenNum 0
set success [CkSsh_SendReqX11Forwarding $ssh $channelNum $singleConnection $authProt $authCookie $screenNum]
if {$success == 0} then {
    puts [CkSsh_lastErrorText $ssh]
    delete_CkSsh $ssh
    exit
}

puts "X11 forwarding requested."

CkSsh_Disconnect $ssh

delete_CkSsh $ssh