[Twisted-Python] Simple ssh problem, please help

[Kevin Ting]

Hi everyone, I am a beginner to Twisted so any help would be appreciated.

I got an example code from the Twisted, Networking Programming Essentials
book:

from twisted.conch import error
from twisted.conch.ssh import transport, connection, keys, userauth,
channel, common
from twisted.internet import defer, protocol, reactor

class ClientCommandTransport(transport.SSHClientTransport):
    def __init__(self, username, password, command):
        self.username = username
        self.password = password
        self.command = command
        print "Transport Created"

    def verifyHostKey(self, pubKey, fingerprint):
        print "In Verify Host Key"
        return defer.succeed(True)

    def connectionSecure(self):
        print "In Connection Secure"
        temp = PasswordAuth(self.username, self.password,
ClientConnection(self.command))
        print "Created Everything"
        self.requestService(temp)
        print "Double Check"

class PasswordAuth(userauth.SSHUserAuthClient):
    def __init__(self, user, password, connection):
        userauth.SSHUserAuthClient.__init__(self, user, connection)
        self.password = password
        print "init password auth"

    def getPassword(self, prompt=None):
        print "In getPassword"
        return defer.succeed(self.password)

class ClientConnection(connection.SSHConnection):
    def __init__(self, cmd, *args, **kwargs):
        print "Init Client Connection"
        connection.SSHConnection.__init__(self)
        print "Next line of Client Connection"
        self.command = cmd

    def serviceStarted(self):
        print "Service Started"
        self.openChannel(CommandChannel(self.command, conn=self))

class CommandChannel(channel.SSHChannel):
    name = 'session'

    def __init__(self, command, *args, **kwargs):
        channel.SSHChannel.__init__(self, *args, **kwargs)
        self.command = command

    def channelOpen(self, data):
        print ("Channel was opened")
        self.conn.sendRequest(self,'exec',common.NS(self.command),wantReply
= True).addCallback(self._gotResponse)

    def _gotResponse(self,_):
        self.conn.sendEOF(self)

    def dataReceived(self, data):
        print data

    def closed(self):
        print("###### Entered Closed #####")
self.loseConnection()
        reactor.stop()
        print("##### Done with Closed ####")

class ClientCommandFactory(protocol.ClientFactory):
    def __init__(self, username, password, command):
        self.username = username
        self.password = password
        self.command = command

    def buildProtocol(self,addr):
        protocol = ClientCommandTransport(
            self.username, self.password, self.command)
        return protocol

if __name__ == "__main__":
    import sys, getpass
    server = sys.argv[1]
    command = sys.argv[2]
    username = raw_input("Username: ")
    password = getpass.getpass("Password: ")
    factory = ClientCommandFactory(username, password, command)
    reactor.connectTCP(server, 22, factory)
    reactor.run()



*************************************************************

But after running this, I get this Unhandled error.  Which is strange
because the reactor is being successfully stopped.  Does anyone have any
clue what this means and how I should go about fixing it?  Thanks!!!!!

Unhandled Error
Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/twisted/internet/posixbase.py",
line 586, in _doReadOrWrite
    why = selectable.doRead()
  File "/usr/lib/python2.7/dist-packages/twisted/internet/tcp.py", line
199, in doRead
    rval = self.protocol.dataReceived(data)
  File "/usr/lib/python2.7/dist-packages/twisted/conch/ssh/transport.py",
line 438, in dataReceived
    self.dispatchMessage(messageNum, packet[1:])
  File "/usr/lib/python2.7/dist-packages/twisted/conch/ssh/transport.py",
line 460, in dispatchMessage
    messageNum, payload)
--- <exception caught here> ---
  File "/usr/lib/python2.7/dist-packages/twisted/python/log.py", line 84,
in callWithLogger
    return callWithContext({"system": lp}, func, *args, **kw)
  File "/usr/lib/python2.7/dist-packages/twisted/python/log.py", line 69,
in callWithContext
    return context.call({ILogContext: newCtx}, func, *args, **kw)
  File "/usr/lib/python2.7/dist-packages/twisted/python/context.py", line
118, in callWithContext
    return self.currentContext().callWithContext(ctx, func, *args, **kw)
  File "/usr/lib/python2.7/dist-packages/twisted/python/context.py", line
81, in callWithContext
    return func(*args,**kw)
  File "/usr/lib/python2.7/dist-packages/twisted/conch/ssh/service.py",
line 44, in packetReceived
    return f(packet)
  File "/usr/lib/python2.7/dist-packages/twisted/conch/ssh/connection.py",
line 314, in ssh_CHANNEL_REQUEST
    channel = self.channels[localChannel]
exceptions.KeyError: 0
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