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(Tcl) TCP or TLS over Multiple Hop SSH to Remote Server

Demonstrates how to use the Chilkat Socket API to connect to a remote server (using TCP or TLS) tunneled through mulitple-hop SSH. The scheme looks like this:

Application => ServerSSH1 => ServerSSH2 => DestinationServer

The ConnectThroughSsh and UseSsh methods are added in Chilkat version 9.5.0.55 to accomplish this task.

Chilkat Tcl Extension Downloads

Chilkat Tcl Extension Downloads

load ./chilkat.dll

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

set ssh1 [new_CkSsh]

# Connect directly to the 1st SSH server.
set success [CkSsh_Connect $ssh1 "serverssh1.com" 22]
if {[expr $success != 1]} then {
    puts [CkSsh_lastErrorText $ssh1]
    delete_CkSsh $ssh1
    exit
}

# Authenticate using login/password:
set success [CkSsh_AuthenticatePw $ssh1 "ssh1Login" "ssh1Password"]
if {[expr $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 "serverssh2.com" 22]
if {[expr $success != 1]} then {
    puts [CkSsh_lastErrorText $ssh2]
    delete_CkSsh $ssh1
    delete_CkSsh $ssh2
    exit
}

# Authenticate with ssh2...
set success [CkSsh_AuthenticatePw $ssh2 "ssh2Login" "ssh2Password"]
if {[expr $success != 1]} then {
    puts [CkSsh_lastErrorText $ssh2]
    delete_CkSsh $ssh1
    delete_CkSsh $ssh2
    exit
}

set socket [new_CkSocket]

# Tell the socket object to connect to our destination server though the ssh2 tunnel (which itself is routed through ssh1).
# The connection looks like this:  ApplicationSocket(TLS) => ServerSSH1 => ServerSSH2 => DestinationServer
set success [CkSocket_UseSsh $socket $ssh2]
if {[expr $success != 1]} then {
    puts [CkSocket_lastErrorText $socket]
    delete_CkSsh $ssh1
    delete_CkSsh $ssh2
    delete_CkSocket $socket
    exit
}

# Connect using TLS to www.chilkatsoft.com
# We could also tunnel a bare TCP connection by specifying port 80 with useTls = 0.
set useTls 1
set maxWaitMillisec 20000
set success [CkSocket_Connect $socket "www.chilkatsoft.com" 443 $useTls $maxWaitMillisec]
if {[expr $success != 1]} then {
    puts [CkSocket_lastErrorText $socket]
    delete_CkSsh $ssh1
    delete_CkSsh $ssh2
    delete_CkSocket $socket
    exit
}

# Once the multiple hop SSH tunneled connection is setup,  the socket programming
# is identical to the normal case where we have a direct connection.

# Tell the socket object that all text is to be sent in the utf-8 encoding,
# and the text received is assumed to be utf-8.
CkSocket_put_StringCharset $socket "utf-8"

# Send an HTTP HEAD request:
set success [CkSocket_SendString $socket "HEAD / HTTP/1.1\r\nHost: www.chilkatsoft.com\r\n\r\n"]
if {[expr $success != 1]} then {
    puts [CkSocket_lastErrorText $socket]
    delete_CkSsh $ssh1
    delete_CkSsh $ssh2
    delete_CkSocket $socket
    exit
}

# Wait a maximum of 4 seconds while no data is forthcoming:
CkSocket_put_MaxReadIdleMs $socket 4000

# Get the 1st response line, which should be "HTTP/1.1 200 OK"
set responseStatusLine [CkSocket_receiveToCRLF $socket]
if {[expr [CkSocket_get_LastMethodSuccess $socket] != 1]} then {
    puts [CkSocket_lastErrorText $socket]
    delete_CkSsh $ssh1
    delete_CkSsh $ssh2
    delete_CkSocket $socket
    exit
}

puts "StatusLine: $responseStatusLine"

# Now get the 1st line of the response header:
set responseHeaderLine [CkSocket_receiveToCRLF $socket]
if {[expr [CkSocket_get_LastMethodSuccess $socket] != 1]} then {
    puts [CkSocket_lastErrorText $socket]
    delete_CkSsh $ssh1
    delete_CkSsh $ssh2
    delete_CkSocket $socket
    exit
}

puts "HeaderLine: $responseHeaderLine"

# Now read the remainder of the response header by reading until a double CRLF is seen:
set remainderOfHeader [CkSocket_receiveUntilMatch $socket "\r\n\r\n"]
if {[expr [CkSocket_get_LastMethodSuccess $socket] != 1]} then {
    puts [CkSocket_lastErrorText $socket]
    delete_CkSsh $ssh1
    delete_CkSsh $ssh2
    delete_CkSocket $socket
    exit
}

puts "Remainder: $remainderOfHeader"

# Close the connection with the server.  This closes the tunnel through ssh2.
# Wait a max of 20 seconds (20000 millsec)
set success [CkSocket_Close $socket 20000]

# 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
delete_CkSocket $socket

 

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