telnet over SSH from server

Question

I am doing ssh to a server using parmiko in python. From there, I need to telnet to several devices and capture the output. I am able to ssh and then telnet to only one device but not ablke to telnet multiple devices from a loop. please suggest me how to do this. I am using the following

import paramiko
import telnetlib

ip = ''
port = 42705
username = ''
password = ''

ssh=paramiko.SSHClient()
ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())
ssh.connect(ip,port,username,password)

f=open("abc.txt", "r")
x=f.readlines()
i=1
if i < 100:
  print i
  cmd = "telnet " + x[i]
  print cmd
  i=i+1


stdin, stdout, stderr = ssh.exec_command(cmd)
stdin.write('''
terminal length 0
show platform
exit
''')

outlines = stdout.readlines()
resp = ''.join(outlines)
print(resp)

when I am not using if statement and directly giving ip, its working good. But I need to telnet multiple devices from same server. Thanks for your reply!

I am now using the following code:

#! /usr/bin/python

import sys
import paramiko


ip=''
port=42705
username=''
password=''
f1=open("abc.txt", 'r')
devices=f1.readlines()

for device in devices:
   device = device.rstrip()
   print device
   command = "telnet " + device
   ssh = paramiko.SSHClient()
   print command
   ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())
   ssh.connect(ip, port, username, password)
   stdin, stdout, stderr = ssh.exec_command(command)
   stdin.write('''
   primenms
   primenms123
   terminal length 0
   show platform
   exit
   ls
   ''')
   outlines = stdout.readlines()
   resp = ''.join(outlines)
   print(resp)
   ssh.close()

f1.close()

It is able to ssh but when I am doing telnet from ssh server, its entering credentials primenms and primenms123 as username and password, which is correct credentials, but its showing as authorization failed. Where am I going wrong? Please help me guys!

Answer 1

You should likely be using a for loop instead:

for i in f.readlines():
    cmd = "telnet {0}".format(i)
    print cmd

Ideally you'd want to execute the commands with:

ssh.exec_command(cmd)

Then you could use it like the following example:

for i in f.readlines():
    cmd = "telnet {0}".format(i)
    ssh.exec_command(cmd)

Without knowing what is within abc.txt you might need other ssh commands in there too.