(Tcl) Multi-Hop SSH (SSH Through SSH)

Demonstrates how to SSH through one SSH server to get to another SSH server. The scheme looks like this:

Application => ServerSSH1 => ServerSSH2

The ConnectThroughSsh method is added in Chilkat version 9.5.0.55 to accomplish this task. Technically, it should be possible to chain any number of servers using the ConnectThroughSsh multiple times:

Application => ServerSSH1 => ServerSSH2 ==> ServerSSH3 => ... => ServerSSHN

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load ./chilkat.dll

# This example assumes the Chilkat API to have been previously unlocked.
# See Global Unlock Sample for sample code.

set ssh1 [new_CkSsh]

# Hostname may be an IP address or domain name:
set hostname "192.168.1.108"
set port 22

# Connect directly to the 1st SSH server:
set success [CkSsh_Connect $ssh1 $hostname $port]
if {$success != 1} then {
    puts [CkSsh_lastErrorText $ssh1]
    delete_CkSsh $ssh1
    exit
}

# Wait a max of 15 seconds when reading responses..
CkSsh_put_IdleTimeoutMs $ssh1 15000

# Authenticate using login/password:
set success [CkSsh_AuthenticatePw $ssh1 "myLogin" "myPassword"]
if {$success != 1} then {
    puts [CkSsh_lastErrorText $ssh1]
    delete_CkSsh $ssh1
    exit
}

# Connect through the 1st SSH connection to reach a 2nd SSH server.
# Note: Any number of SSH connections may be simultaneously tunneled through a single
# existing SSH connection.
set ssh2 [new_CkSsh]

set success [CkSsh_ConnectThroughSsh $ssh2 $ssh1 "someremoteserver.com" 22]
if {$success != 1} then {
    puts [CkSsh_lastErrorText $ssh2]
    delete_CkSsh $ssh1
    delete_CkSsh $ssh2
    exit
}

CkSsh_put_IdleTimeoutMs $ssh2 15000

# Authenticate with ssh2...
set success [CkSsh_AuthenticatePw $ssh2 "myLogin2" "myPassword2"]
if {$success != 1} then {
    puts [CkSsh_lastErrorText $ssh2]
    delete_CkSsh $ssh1
    delete_CkSsh $ssh2
    exit
}

# The application may now is connected and authenticated with ssh2.
# The application can do whatever it desires just as if it was directly
# connected to ssh2.   For example, the application might open
# a session channel to send commands or start a remote shell..
set channelNum [CkSsh_OpenSessionChannel $ssh2]
if {$channelNum < 0} then {
    puts [CkSsh_lastErrorText $ssh2]
    delete_CkSsh $ssh1
    delete_CkSsh $ssh2
    exit
}

# ...
# ...
# ...

# Close the connection with ssh2.  (This closes the the tunnel through ssh1.)
# The connection with ssh1 is still alive, and may be used for more connections.
CkSsh_Disconnect $ssh2

# ...
# ...
# ...

CkSsh_Disconnect $ssh1

delete_CkSsh $ssh1
delete_CkSsh $ssh2