Hello,
I have a python script that executes a python code on a remote host using
SSH. It was working perfectly with Twisted 2.5. The method of returning
private and public has changed in userauth.SSHUserAuthClient (Twisted 8.1).
I was using (Twisted 2.5)
------------------------------------------------
def getPublicKey(self):
return keys.getPublicKeyString(self.keyfile+'.pub')
def getPrivateKey(self):
return defer.succeed(keys.getPrivateKeyObject(self.keyfile))
Now I am using (Twisted 8.1)
----------------------------------------------------
def getPublicKey(self):
return keys.Key.fromFile(self.keyfile+'.pub')
def getPrivateKey(self):
return defer.succeed(keys.Key.fromFile(self.keyfile))
and it doesn't work any more. I have attached the simplified script. Here is
the scenario I am using and the exception I got. Any help is greatly
appreciated.
Scenario
----------------------
I am creating a DSA key using ssh-keygen (in Debian and Ubuntu) with an
empty password
$ ssh-keygen -t dsa
and copy it to my localhost
$ ssh-copy-id -i ~/.ssh/id_dsa localhost
then run the attached script, which tries to execute a python script
remotely using SSH and get the following error
Traceback (most recent call last):
File "/usr/lib/python2.5/site-packages/twisted/internet/selectreactor.py",
line 146, in _doReadOrWrite
why = getattr(selectable, method)()
File "/usr/lib/python2.5/site-packages/twisted/internet/tcp.py", line 362,
in doRead
return self.protocol.dataReceived(data)
File "/usr/lib/python2.5/site-packages/twisted/conch/ssh/transport.py",
line 314, in dataReceived
self.dispatchMessage(messageNum, packet[1:])
File "/usr/lib/python2.5/site-packages/twisted/conch/ssh/transport.py",
line 336, in dispatchMessage
messageNum, payload)
--- <exception caught here> ---
File "/usr/lib/python2.5/site-packages/twisted/python/log.py", line 51, in
callWithLogger
return callWithContext({"system": lp}, func, *args, **kw)
File "/usr/lib/python2.5/site-packages/twisted/python/log.py", line 36, in
callWithContext
return context.call({ILogContext: newCtx}, func, *args, **kw)
File "/usr/lib/python2.5/site-packages/twisted/python/context.py", line
59, in callWithContext
return self.currentContext().callWithContext(ctx, func, *args, **kw)
File "/usr/lib/python2.5/site-packages/twisted/python/context.py", line
37, in callWithContext
return func(*args,**kw)
File "/usr/lib/python2.5/site-packages/twisted/conch/ssh/service.py", line
44, in packetReceived
return f(packet)
File "/usr/lib/python2.5/site-packages/twisted/conch/ssh/userauth.py",
line 262, in ssh_USERAUTH_FAILURE
if method not in self.authenticatedWith and self.tryAuth(method):
File "/usr/lib/python2.5/site-packages/twisted/conch/ssh/userauth.py",
line 234, in tryAuth
return f()
File "/usr/lib/python2.5/site-packages/twisted/conch/ssh/userauth.py",
line 338, in auth_publickey
keyType = getNS(publicKey)[0]
File "/usr/lib/python2.5/site-packages/twisted/conch/ssh/common.py", line
51, in getNS
l, = struct.unpack('!L',s[c:c+4])
exceptions.TypeError: 'Key' object is unsubscriptable
Sincerely
Saki
# -*- coding: utf-8 -*-
#############################################################
# Executes a python code on the remote host using SSH
#############################################################
from twisted.conch.ssh import transport, userauth, connection, common, keys, channel
from twisted.internet import defer, protocol, reactor
from twisted.python import log
import sys, os, re
class lqSSHException(Exception):
def __init__(self, errorcode, message):
self.errorcode = errorcode
self.message = message
def __str__(self):
return '%s %s' % (self.errorcode, self.message)
class lqSSHClient(protocol.ClientFactory):
'''
Executes a remote python code
'''
def __init__(self, username, server, keyfile, command):
'''
Necessary information to connect
'''
self.username = username
self.server = server
self.keyfile = keyfile
self.command = command
self._deferer_ = defer.Deferred()
self._transport = None
def buildProtocol(self, addr):
'''
Create the protocol after connection
'''
self._transport = lqSSHTransport(self.username, self.keyfile, self.command, self._deferer_)
return self._transport
def connect(self):
reactor.connectTCP(self.server, 22, self)
self._deferer_.addCallback(self.disconnectOnSuccess)
self._deferer_.addErrback(self.disconnectOnError)
return self._deferer_
def disconnect(self):
if self._transport is not None:
self._transport.loseConnection()
def disconnectOnError(self, failure):
self.disconnect()
raise failure
def disconnectOnSuccess(self, result):
self.disconnect()
return result
def clientConnectionFailed(self, connector, reason):
'''
When connection failed
'''
protocol.ClientFactory.clientConnectionFailed(self, connector, reason)
log.err(reason)
self._deferer_.errback(reason)
class lqSSHTransport(transport.SSHClientTransport):
def __init__(self, username, keyfile, command, _deferer_):
'''
Necessary info to start SSH connection
'''
self.username = username
self.keyfile = keyfile
self.command = command
self._deferer_ = _deferer_
self.timeout = reactor.callLater(30, self.sshTransportTimeout)
def verifyHostKey(self, hostKey, fingerprint):
'''
Check fingerprint
'''
# print 'host key fingerprint: %s' % fingerprint
self.timeout.cancel()
return defer.succeed(1)
def connectionSecure(self):
'''
User authentication
'''
self.requestService(
lqSSHUserAuth(self.username, self.keyfile, self._deferer_,
lqSSHConnection(self.command, self._deferer_)))
def sshTransportTimeout(self):
'''
If the connection times out
'''
self.loseConnection()
self._deferer_.errback(lqSSHException('408', 'Bağlantı zaman aşımına uğradı'))
class lqSSHUserAuth(userauth.SSHUserAuthClient):
def __init__(self, username, keyfile, _deferer_, connection):
'''
User authentication
'''
userauth.SSHUserAuthClient.__init__(self, username, connection)
self.keyfile = keyfile
self._deferer_ = _deferer_
def getPassword(self):
'''
Password auth is not provided, give error
'''
self.transport.sendDisconnect(transport.DISCONNECT_NO_MORE_AUTH_METHODS_AVAILABLE, 'no more auths')
self._deferer_.errback(lqSSHException('401', 'Wrong Key / Key authentication failed'))
return
def getGenericAnswers(self, name, instruction, questions):
'''
Keyboard interactive password is not provided, give erro
'''
self.transport.sendDisconnect(transport.DISCONNECT_NO_MORE_AUTH_METHODS_AVAILABLE, 'no more auths')
self._deferer_.errback(lqSSHException('401', 'User authentication failed'))
return defer.fail(None)
def getPublicKey(self):
'''
Create the public key
'''
if not os.path.exists(self.keyfile) or self.lastPublicKey:
return
return keys.Key.fromFile(self.keyfile+'.pub')
def getPrivateKey(self):
'''
Create the private key
'''
return defer.succeed(keys.Key.fromFile(self.keyfile))
class lqSSHConnection(connection.SSHConnection):
def __init__(self, command, _deferer_, *args, **kwargs):
'''
Tracks the SSH connection
'''
connection.SSHConnection.__init__(self)
self.command = command
self._deferer_ = _deferer_
def serviceStarted(self):
'''
Runs just after the authentication finished
'''
self.openChannel(lqSSHChannel(self.command, self._deferer_, \
2**16, 2**15, conn=self))
def serviceStopped(self):
'''
Runs if the service stopped
'''
class lqSSHChannel(channel.SSHChannel):
name = 'session'
_buffer = ''
delimiter = '\n'
MAX_LENGTH = 16384
def __init__(self, command, _deferer_, *args, **kwargs):
'''
SSH channel parameters
'''
channel.SSHChannel.__init__(self, *args, **kwargs)
self.command, self.input = command
self._deferer_ = _deferer_
self.success = True
self.output = ''
def openFailed(self, reason):
self._deferer_.errback(reason)
def channelOpen(self, ignoredData):
d = self.conn.sendRequest(self, 'exec', common.NS(self.command), wantReply = True)
d.addCallback(self._cbRequest)
def _cbRequest(self, ignored):
if self.input:
self.write(self.input)
self.conn.sendEOF(self)
def dataReceived(self, data):
"""
Splits the data to lines
"""
lines = (self._buffer+data).split(self.delimiter)
self._buffer = lines.pop(-1)
for line in lines:
if len(line) > self.MAX_LENGTH:
return self.lineLengthExceeded(line)
else:
self.lineReceived(line)
if len(self._buffer) > self.MAX_LENGTH:
return self.lineLengthExceeded(self._buffer)
def lineReceived(self, line):
code, message = line.strip().split(' ', 1)
self.output += line + self.delimiter
if code != '200':
self.success = False
self._deferer_.errback(lqSSHException(code, message))
def lineLengthExceeded(line):
self.success = False
self._deferer_.errback(lqSSHException('500', 'Very long line'))
def extReceived(self, dataType, data):
print "500 Extended data:", dataType, data
def closed(self):
if self.success:
self._deferer_.callback(self.output)
if __name__ == "__main__":
USER = os.getlogin()
HOST = 'localhost'
KEYFILE = os.path.expanduser('~/.ssh/id_dsa')
def done(result):
print result
reactor.stop()
def failed(failure):
print >> sys.stderr, failure.getErrorMessage()
reactor.stop()
remoteCode = "print 'Hello World'"
client = lqSSHClient(USER, HOST, KEYFILE, ('python', remoteCode))
d = client.connect()
d.addCallback(done)
d.addErrback(failed)
reactor.run()
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