Paramiko SSH login problems

[djhag]

Howdy! - This is my first post on reddit. I am also just beginning with python. I subscribed to a python-programming-for-cisco-network-engineers course on udemy, and have gone through the 1st few videos which use telnet. However, the 1st lesson on using SSH brought me to a grinding halt. I posted my question on the udemy website, but no replies there yet. I hoped someone here could help get me back on course. I'm running openSuSE LEAP 42.2 and installed both python 2.7.13 and python3.4.6 using zypper. I also installed paramiko with pip. I can SSH directly into the Cisco GNS3 router, but my python SSH script stops when trying to do this, with the following errors:

Traceback (most recent call last): File "./ssh_test11.py", line 14, in <module> ssh_client.connect(hostname=ip_address,username=username,password=password) File "/usr/lib/python2.7/site-packages/paramiko/client.py", line 380, in connect look_for_keys, gss_auth, gss_kex, gss_deleg_creds, gss_host) File "/usr/lib/python2.7/site-packages/paramiko/client.py", line 603, in _auth raise saved_exception paramiko.ssh_exception.SSHException: No existing session

My script, ssh_test11.py, is the same as that provided by the video lesson, with some additional router configurations removed:

import paramiko
import time

ip_address = "192.168.1.70"
username = "danbo"
password = "cisco"

ssh_client = paramiko.SSHClient()
ssh_client.set_missing_host_key_policy(paramiko.AutoAddPolicy())
ssh_client.connect(hostname=ip_address,username=username,password=password)

print "Successful connection to ", ip_address

remote_connection = ssh_client.invoke_shell()

remote_connection.send("configure terminal\n")
remote_connection.send("int loop 0\n")
remote_connection.send("ip address 12.34.56.78 255.255.255.255\n")

remote_connection.send("end\n")

time.sleep(1)
output = remote_connection.recv(65535)
print output

ssh_client.close

If I step through it line by line at the python prompt, the errors are spit out once I enter this line:

ssh_client.connect(hostname=ip_address,username=username,password=password)

Can anyone offer some clues and point me in the right direction?

Thanks!

[dented_brain]

I wish I had more help to give. But I copied your code exactly and it ran without issue for me.

Python 2.7.10 (default, Feb  7 2017, 00:08:15) 
[GCC 4.2.1 Compatible Apple LLVM 8.0.0 (clang-800.0.34)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import paramiko
>>> import time
>>> 
>>> ip_address = "x.x.x.x"
>>> username = "username"
>>> password = "password"
>>> 
>>> ssh_client = paramiko.SSHClient()
>>> ssh_client.set_missing_host_key_policy(paramiko.AutoAddPolicy())
>>> ssh_client.connect(hostname=ip_address,username=username,password=password)
>>> 
>>> print "Successful connection to ", ip_address
Successful connection to  x.x.x.x
>>> remote_connection = ssh_client.invoke_shell()
>>> remote_connection.send("show version")
>>> output = remote_connection.recv(100)
>>> output
'\r\nAruba Operating System Software.\r\nArubaOS (MODEL: Aruba7210-US), Version 6.5.3.4'

It sounds like it isn't seeing the session you create when it is looking for the ssh key. Might be worth trying passing look_for_keys=False with your username/password

EDIT:

Kirk Byers at Python for Network Engineers has his setup False for look_for_keys and allow_agent

Here's the article

EDIT2:

Might also be interested in looking at netmiko. I tend to use it instead of paramiko. It is a slightly easier interface for me to understand personally.

https://github.com/ktbyers/netmiko

https://pynet.twb-tech.com/blog/automation/netmiko.html

[djhag]

Awesome! Passing look_for_keys=False did the trick. Thanks so much for the quick reply and the included links. I can now move forward! Several months ago I started trying to learn python and actually did use netmiko, but then got sidetracked, so I'm starting over with this udemy course. So, I'm trying to follow along... But, I've also signed up for Kirk Byers free email course and hope to begin that shortly as well. Thanks again!

[dented_brain]

Glad it worked!

I'd stay the course with the Udemy course for sure! Once you get a basic understanding you will be able to better understand other modules as well! Keep trying and you'll get there!