Develop Reference

Cannot close Paramiko connection

I am trying to execute some command on remote server using Paramiko and re-purposed some code from net. From Paramiko documents, it say that you have to close the connection. But I am getting errors while doing that.
class ssh:
paramiko.util.log_to_file("filename_new.log")
client = None
def __init__(self, address, username, password):
self.client=paramiko.SSHClient()
self.client.set_missing_host_key_policy(paramiko.client.AutoAddPolicy())
self.client.connect(hostname=address, username=username, password=password)
def sendCommand(self, command):
if(self.client):
couldNotConnect = False
stdin, stdout, stderr = self.client.exec_command(command, get_pty=True)
stdout = stdout.readlines()
self.client.close()
else:
stdout = "Could Not Connect"
couldNotConnect = True
return stdout
connection = ssh(serverName, userName, passWord)
dfDetails = connection.sendCommand("df -hT")
upTime = connection.sendCommand("uptime")
I am getting the below error:
File "/home/amarc/development/djago/venv/lib/python3.6/site-packages/paramiko/client.py", line 508, in exec_command
chan = self._transport.open_session(timeout=timeout)
AttributeError: 'NoneType' object has no attribute 'open_session'
But when I remove the self.client.close(), it works fine. But I am worried if not closing the connection might cause problem if the program was run multiple times.
And is using __init__ the right way to create a connection since I might be supplying the function with different credentials every time.

I'd recommend you to go for either Fabric (http://www.fabfile.org/) or Ansible and not rely purely on Paramiko since you'll have to reimplement a lot of details. Those tools are already using it but behind the scenes.

The SSHClient.close call has to match with SSHClient.connect.
You call SSHClient.connect once, but SSHClient.close for every command.
Call SSHClient.close only once, after you execute all commands.

Paramiko: Error with windows file paths when transfering file over SFTP

I'm currently working a server-client setup in which I have two separate server scripts. One python script is responsible for running a SSH listener with Paramiko, and that script runs on one machine. I have another server script specifically acting as an SFTP server on another, separate machine, within the same range and subnet as the other one.
My client code is running on a windows 10 system. Both servers are running in unix environments (macOS and Ubuntu 16.04 respectively).
The SFTP server that I am running is aptly titled sftpserver, and is available at https://github.com/rspivak/sftpserver/.
The below code is actually the entirety of my client.py as it stands, minus the import statements.
key = paramiko.RSAKey.from_private_key_file('testkey.key')
transport = paramiko.Transport(('192.168.1.116', 10000))
transport.connect(username='root', password='toor', pkey=key)
client = paramiko.SSHClient()
client.set_missing_host_key_policy(paramiko.AutoAddPolicy())
client.connect('192.168.1.107', username='root', password='toor')
chan = client.get_transport().open_session()
chan.send("Hey man! I'm connected!")
print(chan.recv(1024))
def sftp(localpath, name):
try:
sftp = paramiko.SFTPClient.from_transport(transport)
sftp.put(localpath, '/root/uploads/' + name)
sftp.close()
transport.close()
return "<+> Done uploading"
except Exception as e:
return str(e)
while True:
command = chan.recv(1024).decode()
ipdb.set_trace() // <-- debugging purposes only
if 'grab' in command:
_, path, name = command.split(' ')
chan.send(sftp(path, name))
else:
try:
CMD = subprocess.check_output(command, shell=True)
chan.send(CMD)
except Exception as e:
chan.send(str(e))
client.close()
Executing the grab command in my script looks like this:
grab C:\Users\xxx\testing.txt testing.txt
Now, if I write a path exactly like that (with the back slashes), it will append a second back slash after each one. So, the path I supplied now looks like C:\\Users\xxx\\testing.txt, and this is what I imagine is causing me to receive File not found errors. Thanks to pdb I was able to find this issue, but I am unsure how to continue. In all honesty, I am completely unsure if this problem is paramiko related or if it's some weird python behavior that I haven't encountered yet.
Also, sorry for no stack trace. I'll try to obtain one if possible, but I'm a bit pressed for time right this second.

Python telnetlib client doesn't appear to be opening telnet connection to server

I am trying to open a telnet connection, write one string, then print everything from the telnet server in Python. I assume I am missing something obvious because the documentation seems pretty self-explanatory and doing what I think is the exact same thing in terminal works fine.
Here is the Python code:
import telnetlib
telnet = telnetlib.Telnet()
telnet.open('192.168.1.128', 9801, 10)
telnet.write("SYSTEM_CAL")
print(telnet.read_all())
This times out after 10 seconds / doesn't successfully connect to the server I assume. Here is the output:
Traceback (most recent call last):
File "/Volumes/Work/Scripting/Telnet Test/main.py", line 9, in <module>
print(telnet.read_all())
File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/telnetlib.py", line 385, in read_all
self.fill_rawq()
File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/telnetlib.py", line 576, in fill_rawq
buf = self.sock.recv(50)
socket.timeout: timed out
In the image below I connect to the same server in terminal and everything works fine. At the end I give the "DISCONNECT" command taken by the server which is why the connection closes.
Am I missing something? Why is this working in Terminal and not in Python?

I suppose you are sending your command too early, and the receiving end is ignoring it. Try to read the banner first:
print(telnet.read_until("Welcome."))
telnet.write("SYSTEM_CAL")
print(telnet.read_all())
EDIT:
I also note that you don't have a line-terminating sequence at the end of "SYSTEM_CAL". I presume that, in the interactive session, you press ↵ ENTER after you type "SYSTEM_CAL". If that is the case, you'll need to add \n at the end of the write() call:
telnet.write("SYSTEM_CAL\n")
Depending upon other factors outside of your question, it is possible that you may need one of the following instead:
telnet.write("SYSTEM_CAL\r")
telnet.write("SYSTEM_CAL\r\n")

Python paramiko module using multiple commands

I have a class that creates the connection. I can connect and execute 1 command before the channel is closed. On another system i have i can execute multiple commands and the channel does not close. Obviously its a config issue with the systems i am trying to connect to.
class connect:
newconnection = ''
def __init__(self,username,password):
ssh = paramiko.SSHClient()
ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())
try:
ssh.connect('somehost', username=username,password=password,port=2222,timeout=5)
except:
print "Count not connect"
sys.exit()
self.newconnection = ssh
def con(self):
return self.newconnection
Then i use 'ls' command just to print some output
sshconnection = connect('someuser','somepassword').con()
stdin, stdout, stderr = sshconnection.exec_command("ls -lsa")
print stdout.readlines()
print stdout
stdin, stdout, stderr = sshconnection.exec_command("ls -lsa")
print stdout.readlines()
print stdout
sshconnection.close()
sys.exit()
After the first exec_command runs it prints the expected output of the dir list. When i print stdout after the first exec_command it looks like the channel is closed
<paramiko.ChannelFile from <paramiko.Channel 1 (closed) -> <paramiko.Transport at 0x2400f10L (cipher aes128-ctr, 128 bits) (active; 0 open channel(s))>>>
Like i said on another system i am able to keep running commands and the connection doesn't close. Is there a way i can keep this open? or a better way i can see the reason why it closes?
edit: So it looks like you can only run 1 command per SSHClient.exec_command... so i decided to get_transport().open_session() and then run a command. The first one always works. The second one always fails and the scripts just hangs

With just paramiko after the exec_command executes the channel is closed and the ssh returns an auth prompt.
Seems its not possible with just paramiko, try fabric or another tool.
** fabric did not work out too.

Please see the following referece as it provides a way to do this in Paramiko:
How do you execute multiple commands in a single session in Paramiko? (Python)

it's possible with netmiko (tested on windows).
this example is written for connecting to cisco devices but the principle is adaptable for others as well.
import netmiko
from netmiko import ConnectHandler
import json
def connect_enable_silent(ip_address,ios_command):
with open ("credentials.txt") as line:
line_1 = json.load(line)
for k,v in line_1.items():
router=(k,v)
try:
ssh = ConnectHandler(**router[1],device_type="cisco_ios",ip=ip_address)
ssh.enable()
except netmiko.ssh_exception.NetMikoAuthenticationException:
#incorrect credentials
continue
except netmiko.ssh_exception.NetMikoTimeoutException:
#oddly enough if it can log in but not able to authenticate to enable mode the ssh.enable() command does not give an authentication error
#but a time-out error instead
try:
ssh = ConnectHandler(username = router[1]['username'],password = router[1]['password'],device_type="cisco_ios", ip=ip_address)
except netmiko.ssh_exception.NetMikoTimeoutException:
# connection timed out (ssh not enabled on device, try telnet)
continue
except Exception:
continue
else:
output = ssh.send_command(ios_command)
ssh.disconnect()
if "at '^' marker." in output:
#trying to run a command that requires enble mode but not authenticated to enable mode
continue
return output
except Exception:
continue
else:
output = ssh.send_command(ios_command)
ssh.disconnect()
return output
output = connect_enable_silent(ip_address,ios_command)
for line in output.split('\n'):
print(line)
Credentials text is meant to store different credentials in case you are planning to call this function to access multiple devices and not all of them using the same credentials. It is in the format:
{"credentials_1":{"username":"username_1","password":"password_1","secret":"secret_1"},
"credentials_2":{"username":"username_2","password":"password_2","secret":"secret_2"},
"credentials_3": {"username": "username_3", "password": "password_3"}
}
The exceptions can be changed to do different things, in my case i just needed it to not return an error and continue trying the next set, which is why most exceptions are silenced.

paramiko ssh client does not work with HP switches

I've been using my script for a unix server and it's working perfectly. However when i use the same script( with some minor command changes) to connect to HP Procurve switches , script crashes with error. Part of the script is below:
ssh = paramiko.SSHClient()
ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())
ssh.connect(address, username=userna, password=passwd)
stdin,stdout,stderr= ssh.exec_command("show ver")
for line in stdout:
print '... ' + line.strip('\n')
ssh.close()
This gives error
Traceback (most recent call last):
File "C:/Users/kucar/Desktop/my_python/switchmodel", line 34, in <module>
stdin,stdout,stderr= ssh.exec_command("show ver")
File "C:\Python27\lib\site-packages\paramiko\client.py", line 379, in exec_command
chan.exec_command(command)
File "C:\Python27\lib\site-packages\paramiko\channel.py", line 218, in exec_command
self._wait_for_event()
File "C:\Python27\lib\site-packages\paramiko\channel.py", line 1122, in _wait_for_event
raise e
SSHException: Channel closed.
I've found similar complaints in the web however seems like solution is not provided at all. Switch is open to ssh and works fine with putty. Appreciate if you give any ideas that could help me. I cannot do "show ver" command manually for 100 switches.

As #dobbo mentioned above you have to do invoke_shell() on the channel so that you can execute multiple commands. Also HP ProCurve has ANSI Escape Codes in the output so you have to strip those out. Finally, HP ProCurve throws up a "Press any key to continue" message which you have to get past at least on some devices.
I have an HP ProCurve handler in this library https://github.com/ktbyers/netmiko
Set device_type to "hp_procurve".
Exscript also has some sort of a ProCurve handler though I haven't dug into it enough to get it to work.

I had the same experience connecting to my Samsung s4 phone with an ssh server.
I had no problem connecting to a SUSE VM or a Rasperry Pi and also tried MobaXterm (putty is SO last week).
I have not found the answer but will share my research.
I had a look at the source and found line 1122 in channel.py (copied below).
With my phone (and possibly your HP switch) I have noticed that there is no login message or MOTD at all and when exiting (with putty/mobaXterm) the session doesn't end properly.
In some other reading, I have found that the parameko is not getting much support from the author any more but others are working to port it to python 3x.
Here is the source code I found.
def _wait_for_send_window(self, size):
"""
(You are already holding the lock.)
Wait for the send window to open up, and allocate up to C{size} bytes
for transmission. If no space opens up before the timeout, a timeout
exception is raised. Returns the number of bytes available to send
(may be less than requested).
"""
# you are already holding the lock
if self.closed or self.eof_sent:
return 0
if self.out_window_size == 0:
# should we block?
if self.timeout == 0.0:
raise socket.timeout()
# loop here in case we get woken up but a different thread has filled the buffer
timeout = self.timeout
while self.out_window_size == 0:
if self.closed or self.eof_sent:
return 0
then = time.time()
self.out_buffer_cv.wait(timeout)
if timeout != None:
timeout -= time.time() - then
if timeout <= 0.0:
raise socket.timeout()
# we have some window to squeeze into

It seems that if you don't clean up the connection buffer Paramiko goes nuts when working with HP Procurves. First off you need to invoke a shell or Paramiko will simply drop the connection after the first command (normal behavior, but confusing).
ssh = paramiko.SSHClient()
ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())
ssh.connect(switch_ip, username=switch_user, password=switch_pass,look_for_keys=False)
conn = ssh.invoke_shell()
recieveData() # <-- see below
It's important to actually handle the data, and as I've learned you need to make sure Paramiko has actually received all the data before you ask it to do stuff with it. I do this by using the following function. You can adjust the sleep as needed, in some cases 0.050 will work fine.
def recieveData():
tCheck = 0
while not conn.recv_ready():
time.sleep(1)
tCheck+=1
if tCheck >=10:
print "time out"
cleanThatStuffUp(conn.recv(1024)) # <-- see below
This is an example of the garbage that is returning to your ssh client.
[1;24r[24;1H[24;1H[2K[24;1H[?25h[24;1H[24;1HProCurve Switch 2650# [24;1H[24;23H[24;1H[?5h[24;23H[24;23Hconfigure[24;23H[?25h[24;32H[24;0HE[24;1H[24;32H[24;1H[2K[24;1H[?5h[24;1H[1;24r[24;1H[1;24r[24;1H[24;1H[2K[24;1H[?25h[24;1H[24;1H
There's also exit codes to deal with before each "[". So to deal with that I figured out some regex to clean all of that "stuff" up.
procurve_re1 = re.compile(r'(\[\d+[HKJ])|(\[\?\d+[hl])|(\[\d+)|(\;\d+\w?)')
procurve_re2 = re.compile(r'([E]\b)')
procurve_re3 = re.compile(ur'[\u001B]+') #remove stupid escapes
def cleanThatStuffUp(message):
message = procurve_re1.sub("", message)
message = procurve_re2.sub("", message)
message = procurve_re3.sub("", message)
print message
Now you can go about entering commands, just make sure you clear out the buffer each time using recieveData().
conn.send("\n") # Get past "Press any key"
recieveData()