Telnet login timing

[Andre Castro]

Dear colleagues

I'm running a script to automate bulk commands across devices and some of them I can only access via telnet.

However it seems like the connect() functions sometimes misses the login time and ends up failing:

aix@N10-ACASTRO:~/pyats2$ /usr/bin/python3 /home/aix/pyats2/main.py

2021-06-08 14:54:38,901: %UNICON-INFO: +++ RT-BIOCOM-TRANSBRAS logfile /tmp/RT-1-cli-20210608T145438895.log +++

2021-06-08 14:54:38,902: %UNICON-INFO: +++ Unicon plugin ios +++
Trying 10.9.248.1...


2021-06-08 14:54:38,943: %UNICON-INFO: +++ connection to spawn: telnet 10.9.248.1, id: 140453737108536 +++

2021-06-08 14:54:38,944: %UNICON-INFO: connection to RT-1
Connected to 10.9.248.1.
Escape character is '^]'.



User Access Verification

Username: Um erro ocorreu ao conectar ao dispositivo Device RT-BIOCOM-TRANSBRAS, type ios
Conectando ao dispositivo Device RT-1, type ios
Trying 10.9.248.1...


2021-06-08 14:54:50,871: %UNICON-INFO: +++ connection to spawn: telnet 10.9.248.1, id: 140453703976160 +++

2021-06-08 14:54:50,872: %UNICON-INFO: connection to RT-1
Connected to 10.9.248.1.
Escape character is '^]'.

Is there any way to fix or adjust the timing properly?

Below a python snippet

from genie.conf import Genie
testbed = Genie.init("my-testbed-2.yaml")
for device in testbed:
     device.connect()

Thank you

[Alex Stevenson]

Hello @Andre Castro,

Is there a specific orchestration or management software you're using? I'd like to know which technology and which release version you're running before I make any suggestions. I think other user could benefit from that as well.

Best regards!

[Andre Castro]

Hi @Alex Stevenson 

No, I'm just using my own script to run batch commands.

Thanks!

[renanhingel]

Hello Andre,

Like Alex mentioned above, we need more information before we can make suggestions. However, if you're still facing the issue, I'd recommend you to test the telnetlib in a separated environment so you can learn how to use it and the outputs you'll receive while using it.

Telnetlib comes with Python and it supports timeout, here's the docs: https://docs.python.org/3/library/telnetlib.html

A simple code snippet with telnet and send a command:

import socket
import telnetlib
import time

device = ""
user = ""
password = ""

try:
    client = telnetlib.Telnet(host=device,port=23, timeout=100)
    client.read_until(b"username: ")
    client.write(user.encode('ascii') + b"\n")
    if password:
        client.read_until(b"password: ")
        client.write(password.encode('ascii') + b"\n")
    client.write(b"show ip int brief\n")
    time.sleep(2)
    client.write(b"exit\n"))
    print(client.read_all().decode('ascii'))

except socket.timeout:
    print("Socket timed out while connecting to " + device)

Hope that can shed some light, let us know if you solved the issue.

Best Regards,

Renan

[Andre Castro]

Hi @renanhingel 

Thank you for the suggestion.

Surely I can use this method but I'm still curious about the pyATS library, as opposed to Ansible for instance which runs flawlessly, there is a lot of additional overhead in it though.

Cheers!

[__Babygirl__09]

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