Tcl

Get the Type of an Active SSH Channel

Demonstrates the Chilkat Ssh.GetChannelType method, which returns the type of the channel at a zero-based enumeration index. The only argument is the index — an enumeration position, not a channel number. Values include session, x11, forwarded-tcpip, and direct-tcpip.

Background: Paired with GetChannelNumber, this turns the channel collection into a readable inventory of what a connection is currently doing — which channels are running commands (session) versus tunneling TCP traffic (direct-tcpip). That is valuable for diagnostics and for application code that manages several channel kinds at once. An out-of-range index causes the string-returning method to report failure.

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Tcl


load ./chilkat.dll

set success 0

#  Demonstrates the Ssh.GetChannelType method, which returns the type of the channel at a
#  zero-based enumeration index.  The only argument is the index, which is an enumeration
#  position and not a channel number.  Values include "session" and "direct-tcpip".

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
}

set channelNum [CkSsh_OpenSessionChannel $ssh]
if {$channelNum < 0} then {
    puts [CkSsh_lastErrorText $ssh]
    delete_CkSsh $ssh
    exit
}

#  Enumerate the active channels and report each one's number and type.
set n [CkSsh_get_NumOpenChannels $ssh]

for {set i 0} {$i <= [expr $n - 1]} {incr i} {
    set chNum [CkSsh_GetChannelNumber $ssh $i]
    set chType [CkSsh_getChannelType $ssh $i]
    if {[CkSsh_get_LastMethodSuccess $ssh] == 0} then {
        puts [CkSsh_lastErrorText $ssh]
        delete_CkSsh $ssh
        exit
    }

    puts "Channel $chNum is of type $chType"
}

CkSsh_Disconnect $ssh

delete_CkSsh $ssh