I’m building an Python application that has to connect and disconnect from Wifi on linux box. I’m using NetworkManager layer, through the nice networkmanager lib found in cnetworkmanager (a python CLI for NetworkManager http://vidner.net/martin/software/cnetworkmanager/ thanx to Martin Vidner), in a daemon (named stationd).
This daemon runs a gobject.MainLoop. Once a timeout_add_seconds awake (triggers by a action of user in GUI), I have to disconnect current running Wifi and connect to a new one:
from dbus.mainloop.glib import DBusGMainLoop
DBusGMainLoop(set_as_default=True)
from networkmanager import NetworkManager
import networkmanager.applet.settings as settings
from networkmanager.applet import USER_SERVICE
from networkmanager.applet.service import NetworkManagerUserSettings, NetworkManagerSettings
import time
import memcache
import gobject
loop = gobject.MainLoop()
nm = NetworkManager()
dummy_handler = lambda *args: None
cache = memcache.Client(['127.0.0.1:11211',] )
def get_device(dev_spec, hint):
candidates = []
devs = NetworkManager().GetDevices()
for dev in devs:
if dev._settings_type() == hint:
candidates.append(dev)
if len(candidates) == 1:
return candidates[0]
for dev in devs:
if dev["Interface"] == dev_spec:
return dev
print "Device '%s' not found" % dev_spec
return None
def kill_allconnections():
connections=nm['ActiveConnections']
for c in connections:
print c.object_path
nm.DeactivateConnection(c.object_path)
class Wifi(object):
def connect(self, ssid, security="open", password=None):
"Connects to given Wifi network"
c=None # connection settings
us = NetworkManagerUserSettings([])
if security=="open":
c = settings.WiFi(ssid)
elif security=="wep":
c = settings.Wep(ssid, password)
elif security=="wpa":
c = settings.WpaPsk(ssid, password)
else:
raise AttributeError("invalid security model '%s'"%security)
svc = USER_SERVICE
svc_conn = us.addCon(c.conmap)
hint = svc_conn.settings["connection"]["type"]
dev = get_device("", hint)
appath = "/"
nm.ActivateConnection(svc, svc_conn, dev, appath, reply_handler=dummy_handler, error_handler=dummy_handler)
def change_network_settings():
key="station:network:change"
change=cache.get(key)
if change is not None:
print "DISCONNECT"
kill_allconnections()
print "CHANGE SETTINGS"
wifi=cache.get(key+':wifi')
if wifi is not None:
ssid=cache.get(key+':wifi:ssid')
security=cache.get(key+':wifi:security')
password=cache.get(key+':wifi:password')
print "SWITCHING TO %s"%ssid
Wifi().connect(ssid, security, password)
cache.delete(key)
return True
def mainloop():
gobject.timeout_add_seconds(1, change_network_settings)
try:
loop.run()
except KeyboardInterrupt:
loop.quit()
if __name__=="__main__":
mainloop()
This runs perfectly for a first connection (read : the box is not connected, daemon is ran and box connects flawlessly to Wifi). Issue is when I try to connect to another Wifi : kill_allconnections() is ran silently, and connect method raises an exception on nm.ActivateConnection:
Traceback (most recent call last):
File "stationd.py", line 40, in change_network_settings
Wifi().connect(ssid, security, password)
File "/home/biopredictive/station/lib/network.py", line 88, in connect
us = NetworkManagerUserSettings([])
File "/home/biopredictive/station/lib/networkmanager/applet/service/__init__.py", line 71, in __init__
super(NetworkManagerUserSettings, self).__init__(conmaps, USER_SERVICE)
File "/home/biopredictive/station/lib/networkmanager/applet/service/__init__.py", line 33, in __init__
dbus.service.Object.__init__(self, bus, opath, bus_name)
File "/usr/lib/pymodules/python2.6/dbus/service.py", line 480, in __init__
self.add_to_connection(conn, object_path)
File "/usr/lib/pymodules/python2.6/dbus/service.py", line 571, in add_to_connection
self._fallback)
KeyError: "Can't register the object-path handler for '/org/freedesktop/NetworkManagerSettings': there is already a handler"
It looks like my former connection didn’t release all its resources ?
I’m very new to gobject/dbus programming. Would you please help ?
I have answered on the D-Bus mailing list. Quoting here for the archive:
class Wifi(...):
def connect(...):
...
us = NetworkManagerUserSettings([])
NetworkManagerUserSettings is a server, not a client. (It's a design
quirk of NM which was eliminated in NM 0.9)
You should create only one for the daemon, not for each conection
attempt.
Related
I implemented a Twisted SSH server to test a component that uses fabric to run commands on a remote machine via SSH. I have found this example but I don't understand how I have to implement the execCommand method to be compatible with fabric. Here is my implementation of the SSH server:
from pathlib import Path
from twisted.conch import avatar, recvline
from twisted.conch.insults import insults
from twisted.conch.interfaces import ISession
from twisted.conch.ssh import factory, keys, session
from twisted.cred import checkers, portal
from twisted.internet import reactor
from zope.interface import implementer
SSH_KEYS_FOLDER = Path(__file__).parent.parent / "resources" / "ssh_keys"
#implementer(ISession)
class SSHDemoAvatar(avatar.ConchUser):
def __init__(self, username: str):
avatar.ConchUser.__init__(self)
self.username = username
self.channelLookup.update({b"session": session.SSHSession})
def openShell(self, protocol):
pass
def getPty(self, terminal, windowSize, attrs):
return None
def execCommand(self, protocol: session.SSHSessionProcessProtocol, cmd: bytes):
protocol.write("Some text to return")
protocol.session.conn.sendEOF(protocol.session)
def eofReceived(self):
pass
def closed(self):
pass
#implementer(portal.IRealm)
class SSHDemoRealm(object):
def requestAvatar(self, avatarId, _, *interfaces):
return interfaces[0], SSHDemoAvatar(avatarId), lambda: None
def getRSAKeys():
with open(SSH_KEYS_FOLDER / "ssh_key") as private_key_file:
private_key = keys.Key.fromString(data=private_key_file.read())
with open(SSH_KEYS_FOLDER / "ssh_key.pub") as public_key_file:
public_key = keys.Key.fromString(data=public_key_file.read())
return public_key, private_key
if __name__ == "__main__":
sshFactory = factory.SSHFactory()
sshFactory.portal = portal.Portal(SSHDemoRealm())
users = {
"admin": b"aaa",
"guest": b"bbb",
}
sshFactory.portal.registerChecker(checkers.InMemoryUsernamePasswordDatabaseDontUse(**users))
pubKey, privKey = getRSAKeys()
sshFactory.publicKeys = {b"ssh-rsa": pubKey}
sshFactory.privateKeys = {b"ssh-rsa": privKey}
reactor.listenTCP(22222, sshFactory)
reactor.run()
Trying to execute a command via fabric yields the following output:
[paramiko.transport ][INFO ] Connected (version 2.0, client Twisted_22.4.0)
[paramiko.transport ][INFO ] Authentication (password) successful!
Some text to return
This looks promising but the program execution hangs after this line. Do I have to close the connection from the server side after executing the command? How do I implement that properly?
In a traditional UNIX server, it's still the server's responsibility to close the connection if it was told to execute a command. It's up to the server's discretion where and how to do this.
I believe you just want to change protocol.session.conn.sendEOF(protocol.session) to protocol.loseConnection(). I apologize for not testing this myself to be sure, setting up an environment to properly test a full-size conch setup like this is a bit tedious (and the example isn't self-contained, requiring key generation and moduli, etc)
This question already has an answer here:
Tornado "error: [Errno 24] Too many open files" error
(1 answer)
Closed 9 years ago.
We are running a Tornado 3.0 service on a RedHat OS and getting the following error:
[E 140102 17:07:37 ioloop:660] Exception in I/O handler for fd 11
Traceback (most recent call last):
File "/usr/local/lib/python2.7/dist-packages/tornado/ioloop.py", line 653, in start
self._handlers[fd](fd, events)
File "/usr/local/lib/python2.7/dist-packages/tornado/stack_context.py", line 241, in wrapped
callback(*args, **kwargs)
File "/usr/local/lib/python2.7/dist-packages/tornado/netutil.py", line 136, in accept_handler
connection, address = sock.accept()
File "/usr/lib/python2.7/socket.py", line 202, in accept
error: [Errno 24] Too many open files
But we couldn't figure out what that means.
Our Tornado code is as follows:
import sys
from tornado.ioloop import IOLoop
from tornado.options import parse_command_line, define, options
from tornado.httpserver import HTTPServer
from tornado.netutil import bind_sockets
import tornado
sys.path.append("..")
from tornado.web import RequestHandler, Application
from shared.bootstrap import *
from time import time
from clients import ClientFactory
from shared.configuration import Config
from shared.logger import Logger
from algorithms.neighborhood.application import NeighborhoodApplication
import traceback
define('port', default=8000, help="Run on the given port", type=int)
define('debug', default=True, help="Run application in debug mode", type=bool)
class WService(RequestHandler):
_clients = {}
def prepare(self):
self._start_time = time()
RequestHandler.prepare(self)
def get(self, algorithm = None):
self.add_header('Content-type', 'application/json')
response = {'skus' : []}
algorithm = 'neighborhood' if not algorithm else algorithm
try:
if not algorithm in self._clients:
self._clients[algorithm] = ClientFactory.get_instance(algorithm)
arguments = self.get_arguments_by_client(self._clients[algorithm].get_expected_arguments())
response['skus'] = app.get_manager().make_recommendations(arguments)
self.write(response)
except Exception as err:
self.write(response)
error("Erro: " + str(err))
def get_arguments_by_client(self, expected_arguments):
arguments = {}
for key in expected_arguments:
arguments[key] = self.get_argument(key, expected_arguments[key])
return arguments
def on_connection_close(self):
self.finish({'skus':[]})
RequestHandler.on_connection_close(self)
def on_finish(self):
response_time = 1000.0 *(time() - self._start_time)
log("%d %s %.2fms" % (self.get_status(), self._request_summary(), response_time))
RequestHandler.on_finish(self)
def handling_exception(signal, frame):
error('IOLoop blocked for %s seconds in\n%s\n\n' % ( io_loop._blocking_signal_threshold, ''.join(traceback.format_stack(frame)[-3:])))
if __name__ == "__main__":
configuration = Config()
Logger.configure(configuration.get_configs('logger'))
app = NeighborhoodApplication({
'application': configuration.get_configs('neighborhood'),
'couchbase': configuration.get_configs('couchbase'),
'stock': configuration.get_configs('stock')
})
app.run()
log("Neighborhood Matrices successfully created...")
log("Initiating Tornado Service...")
parse_command_line()
application = Application([
(r'/(favicon.ico)', tornado.web.StaticFileHandler, {"path": "./images/"}),
(r"/(.*)", WService)
], **{'debug':options.debug, 'x-headers' : True})
sockets = bind_sockets(options.port, backlog=1024)
server = HTTPServer(application)
server.add_sockets(sockets)
io_loop = IOLoop.instance()
io_loop.set_blocking_signal_threshold(.05, handling_exception)
io_loop.start()
It's a very basic script, basically it gets the URL, process it in the make_recommendation function and sends back the response.
We've tried to set a tornado timeout of 50 ms through the io_loop.set_blocking_signal_threshold function as sometimes the processing of the URL might take this long.
The system receives around 8000 requests per minute and it worked fine for about 30 minutes, but after that it started throwing the "too many files error" and broke down. On general the requests were taking about 20 ms to get processed but when the error started happening the time consumed increased to seconds, all of a sudden.
We tried to see how many connections the port 8000 had and it had several open connections all with the "ESTABLISHED" status.
Is there something wrong in our Tornado script? We believe our timeout function is not working properly, but for what we've researched so far everything seems to be ok.
If you need more info please let me know.
Thanks in advance,
Many linux distributions ship with very low limits (e.g. 250) for the number of open files per process. You can use "ulimit -n" to see the current value on your system (be sure to issue this command in the same environment that your tornado server runs as). To raise the limit you can use the ulimit command or modify /etc/security/limits.conf (try setting it to 50000).
Tornado's HTTP server does not (as of version 3.2) close connections that a web browser has left open, so idle connections may accumulate over time. This is one reason why it is recommended to use a proxy like nginx or haproxy in front of a Tornado server; these servers are more hardened against this and other potential DoS issues.
I need a class which gives me a list of avahi services of a certain type which a currently available. Therefor I run a gobject.MainLoop() (line 23-25) in a separate thread an add a browser for each service I am interested in (line 27,28). This works in principle.
My problem is, that I do not get always all services. Sometimes all services that are available are listed, sometimes none of them, sometimes just a few. My guess is, that the browser starts iterating the services (line 36) before the appropriate signals are connected (line 41-44), but I have no clue how to fix this. Below a minimal example which shows the failure.
Most examples I have seen on the net (e.g.: Stopping the Avahi service and return a list of elements) run the MainLoop after the browser is set up and the signals are connected. The loop is then quit when the "AllForNow" signal is received. This is not an option for me as the Browser should keep running and listen for new or removed services (which works reliable by the way, just the initial query is problematic).
#!/usr/bin/python
import dbus
from dbus.mainloop.glib import DBusGMainLoop
import avahi
import gobject
import threading
gobject.threads_init()
dbus.mainloop.glib.threads_init()
class ZeroconfBrowser:
def __init__(self):
self.service_browsers = set()
self.services = {}
self.lock = threading.Lock()
loop = DBusGMainLoop(set_as_default=True)
self._bus = dbus.SystemBus(mainloop=loop)
self.server = dbus.Interface(
self._bus.get_object(avahi.DBUS_NAME, avahi.DBUS_PATH_SERVER),
avahi.DBUS_INTERFACE_SERVER)
thread = threading.Thread(target=gobject.MainLoop().run)
thread.daemon = True
thread.start()
self.browse("_ssh._tcp")
self.browse("_http._tcp")
def browse(self, service):
if service in self.service_browsers:
return
self.service_browsers.add(service)
with self.lock:
browser = dbus.Interface(self._bus.get_object(avahi.DBUS_NAME,
self.server.ServiceBrowserNew(avahi.IF_UNSPEC,
avahi.PROTO_UNSPEC, service, 'local', dbus.UInt32(0))),
avahi.DBUS_INTERFACE_SERVICE_BROWSER)
browser.connect_to_signal("ItemNew", self.item_new)
browser.connect_to_signal("ItemRemove", self.item_remove)
browser.connect_to_signal("AllForNow", self.all_for_now)
browser.connect_to_signal("Failure", self.failure)
def resolved(self, interface, protocol, name, service, domain, host,
aprotocol, address, port, txt, flags):
print "resolved", interface, protocol, name, service, domain, flags
def failure(self, exception):
print "Browse error:", exception
def item_new(self, interface, protocol, name, stype, domain, flags):
with self.lock:
self.server.ResolveService(interface, protocol, name, stype,
domain, avahi.PROTO_UNSPEC, dbus.UInt32(0),
reply_handler=self.resolved, error_handler=self.resolve_error)
def item_remove(self, interface, protocol, name, service, domain, flags):
print "removed", interface, protocol, name, service, domain, flags
def all_for_now(self):
print "all for now"
def resolve_error(self, *args, **kwargs):
with self.lock:
print "Resolve error:", args, kwargs
import time
def main():
browser = ZeroconfBrowser()
while True:
time.sleep(3)
for key, value in browser.services.items():
print key, str(value)
if __name__ == '__main__':
main()
I couldn't find an installable python-dbus package. However I did find an example Avahi browser which works great -- avahi.py
pip install python-tdbus
source
#!/usr/bin/env python
#
# This file is part of python-tdbus. Python-tdbus is free software
# available under the terms of the MIT license. See the file "LICENSE" that
# was provided together with this source file for the licensing terms.
#
# Copyright (c) 2012 the python-tdbus authors. See the file "AUTHORS" for a
# complete list.
# This example shows how to access Avahi on the D-BUS.
from tdbus import SimpleDBusConnection, DBUS_BUS_SYSTEM, DBusHandler, signal_handler, DBusError
import logging
logging.basicConfig(level=logging.DEBUG)
CONN_AVAHI = 'org.freedesktop.Avahi'
PATH_SERVER = '/'
IFACE_SERVER = 'org.freedesktop.Avahi.Server'
conn = SimpleDBusConnection(DBUS_BUS_SYSTEM)
try:
result = conn.call_method(PATH_SERVER, 'GetVersionString',
interface=IFACE_SERVER, destination=CONN_AVAHI)
except DBusError:
print 'Avahi NOT available.'
raise
print 'Avahi is available at %s' % CONN_AVAHI
print 'Avahi version: %s' % result.get_args()[0]
print
print 'Browsing service types on domain: local'
print 'Press CTRL-c to exit'
print
result = conn.call_method('/', 'ServiceTypeBrowserNew', interface=IFACE_SERVER,
destination=CONN_AVAHI, format='iisu', args=(-1, 0, 'local', 0))
browser = result.get_args()[0]
print browser
class AvahiHandler(DBusHandler):
#signal_handler()
def ItemNew(self, message):
args = message.get_args()
print 'service %s exists on domain %s' % (args[2], args[3])
conn.add_handler(AvahiHandler())
conn.dispatch()
output
Avahi is available at org.freedesktop.Avahi
Avahi version: avahi 0.6.31
Browsing service types on domain: local
Press CTRL-c to exit
/Client1/ServiceTypeBrowser1
service _udisks-ssh._tcp exists on domain local
service _workstation._tcp exists on domain local
service _workstation._tcp exists on domain local
service _udisks-ssh._tcp exists on domain local
Hi I am trying to write a simple thrift server in python (named PythonServer.py) with a single method that returns a string for learning purposes. The server code is below. I am having the following errors in the Thrift's python libraries when I run the server. Has anyone experienced this problem and suggest a workaround?
The execution output:
Starting server
Traceback (most recent call last):
File "/home/dae/workspace/BasicTestEnvironmentV1.0/src/PythonServer.py", line 38, in <module>
server.serve()
File "usr/lib/python2.6/site-packages/thrift/server/TServer.py", line 101, in serve
File "usr/lib/python2.6/site-packages/thrift/transport/TSocket.py", line 136, in listen
File "usr/lib/python2.6/site-packages/thrift/transport/TSocket.py", line 31, in _resolveAddr
TypeError: getaddrinfo() argument 1 must be string or None
PythonServer.java
port = 9090
import MyService as myserv
#from ttypes import *
# Thrift files
from thrift.transport import TSocket
from thrift.transport import TTransport
from thrift.protocol import TBinaryProtocol
from thrift.server import TServer
# Server implementation
class MyHandler:
# return server message
def sendMessage(self, text):
print text
return 'In the garage!!!'
# set handler to our implementation
handler = MyHandler()
processor = myserv.Processor(handler)
transport = TSocket.TServerSocket(port)
tfactory = TTransport.TBufferedTransportFactory()
pfactory = TBinaryProtocol.TBinaryProtocolFactory()
# set server
server = TServer.TThreadedServer(processor, transport, tfactory, pfactory)
print 'Starting server'
server.serve() ##### LINE 38 GOES HERE ##########
Your problem is the line:
transport = TSocket.TServerSocket(port)
When calling TSocket.TServerSocket which a single argument, the value is treated as a host identifier, hence the error with getaddrinfo().
To fix that, change the line to:
transport = TSocket.TServerSocket(port=port)
I had this problem while running PythonServer.py ...
I changed this line
transport = TSocket.TServerSocket(9090)
to
transport = TSocket.TServerSocket('9090')
and my server started running.
I had a similar problem. My fix is
TSocket.TServerSocket('your server ip',port)
I'm working on a script that spins up a fresh EC2 instance with boto and uses the Paramiko SSH client to execute remote commands on the instance. For whatever reason, the Paramiko client is unabled to connect, I get the error:
Traceback (most recent call last):
File "scripts/sconfigure.py", line 29, in <module>
ssh.connect(instance.ip_address, username='ubuntu', key_filename=os.path.expanduser('~/.ssh/test'))
File "build/bdist.macosx-10.3-fat/egg/paramiko/client.py", line 291, in connect
File "<string>", line 1, in connect
socket.error: [Errno 61] Connection refused
I can ssh in fine manually using the same key file and user. Has anyone run into issues using Paramiko? My full code is below. Thanks.
import boto.ec2, time, paramiko, os
# Connect to the us-west-1 region
ec2 = boto.ec2.regions()[3].connect()
image_id = 'ami-ad7e2ee8'
image_name = 'Ubuntu 10.10 (Maverick Meerkat) 32-bit EBS'
new_reservation = ec2.run_instances(
image_id=image_id,
key_name='test',
security_groups=['web'])
instance = new_reservation.instances[0]
print "Spinning up instance for '%s' - %s. Waiting for it to boot up." % (image_id, image_name)
while instance.state != 'running':
print "."
time.sleep(1)
instance.update()
print "Instance is running, ip: %s" % instance.ip_address
print "Connecting to %s as user %s" % (instance.ip_address, 'ubuntu')
ssh = paramiko.SSHClient()
ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())
ssh.connect(instance.ip_address, username='ubuntu', key_filename=os.path.expanduser('~/.ssh/test'))
stdin, stdout, stderr = ssh.exec_command('echo "TEST"')
print stdout.readlines()
ssh.close()
I seem to have figured this out by trial and error. Even though the instance status is "running" according to boto, there is a delay for when it will actually allow an SSH connection. Adding a "time.sleep(30)" before the "ssh.connect(...)" seems to do the trick for me, though this may vary.
The way to check it's ssh available is to make sure its two status checks both passes. On web UI it looks like this:
And using boto3 (the original question used boto but it was 5 years ago), we can do:
session = boto3.Session(...)
client = session.client('ec2')
res = client.run_instances(...) # launch instance
instance_id = res['Instances'][0]['InstanceId']
while True:
statuses = client.describe_instance_status(InstanceIds=[instance_id])
status = statuses['InstanceStatuses'][0]
if status['InstanceStatus']['Status'] == 'ok' \
and status['SystemStatus']['Status'] == 'ok':
break
print '.'
time.sleep(5)
print "Instance is running, you are ready to ssh to it"
Why not use boto.manage.cmdshell instead?
cmd = boto.manage.cmdshell.sshclient_from_instance(instance,
key_path,
user_name='ec2_user')
(code taken from line 152 in ec2_launch_instance.py)
For available cmdshell commands have a look at the SSHClient class from cmdshell.py.
I recently ran into this issue. The "correct" way would be to initiate a close() first and then reopen the connection. However on older versions, close() was broken.
With this version or later, it should be fixed:
https://github.com/boto/boto/pull/412
"Proper" method:
newinstance = image.run(min_count=instancenum, max_count=instancenum, key_name=keypair, security_groups=security_group, user_data=instancename, instance_type=instancetype, placement=zone)
time.sleep(2)
newinstance.instances[0].add_tag('Name',instancename)
print "Waiting for public_dns_name..."
counter = 0
while counter < 70:
time.sleep(1)
conn.close()
conn = boto.ec2.connection.EC2Connection(ec2auth.access_key,ec2auth.private_key)
startedinstance = conn.get_all_instances(instance_ids=str(newinstance.instances[0].id))[0]
counter = counter + 1
if str(startedinstance.instances[0].state) == "running":
break
if counter == 69:
print "Timed out waiting for instance to start."
print "Added: " + startedinstance.instances[0].tags['Name'] + " " + startedinstance.instances[0].public_dns_name
I recently view this code and I have a suggestion for code,
Instead of running while loop to check whether the instance is running or not, you can try "wait_until_running()".
Following is the sample code...
client = boto3.resource(
'ec2',
region_name="us-east-1"
)
Instance_ID = "<your Instance_ID>"
instance = client.Instance(Instance_ID)
instance.start()
instance.wait_until_running()
After that try to code for the ssh connection code.