Executing passwd command in Python Paramiko to change a password on a Linux server

Question

I am trying to write a Python 3 script to pragmatically ssh into a Linux server and change the password. I have put a script together using the Paramiko module.

I am running into issues when trying to run multiple shell commands. My script attempts to execute the commands but Paramiko times out after one shell command.

This is the script I am currently working on. Any insight would be greatly appreciated.

import paramiko

def change_pw():
    hostname = "IP" #IP Address of Linux Server
    username = "root" #username
    password = "oldpw!" #password for Linux Server

#NOTE - This variable is suppose to define 3 shell commands. I do not believe the script is sending these commands as listed because the password does not update.
    commands = [
        "passwd",
        "newpw!",
        "newpw!"
    ]

#NOTE - Attempted to utilize '\n' to execute multiple commands and failed
    # commands = [
    #     "passwd \n newpw! \n newpw!"
    # ]

    # initialize the SSH clientp0-
    client = paramiko.SSHClient()
    # add to known hosts
    client.set_missing_host_key_policy(paramiko.AutoAddPolicy())
    try:
        client.connect(hostname=hostname, username=username, password=password)
    except:
        print("[!] Cannot connect to the SSH Server")
        exit()

    # execute the commands
    for command in commands:
        print("="*50, command, "="*50)
        stdin, stdout, stderr = client.exec_command(command)
        print(stdout.read().decode())
        err = stderr.read().decode()
        if err:
            print(err)

change_pw()

Answer 1

You do not have three commands. You have one command, the passwd , which takes two lines of input.

These two questions show how to provide an input to commands using Paramiko:

• Pass input/variables to command/script over SSH using Python Paramiko
• Executing command using "su -l" in SSH using Python

So specifically for passwd , you need to use:

stdin, stdout, stderr = client.exec_command('passwd')
# answer the new password prompts
stdin.write('newpw\n')
stdin.write('newpw\n')
stdin.flush()
# wait for the command to complete a print the output
stdout.channel.set_combine_stderr(True)
print(stdout.read().decode())

For the purpose of the Channel.set_combine_stderr , see Paramiko ssh die/hang with big output .

---

Obligatory warning: Do not use AutoAddPolicy – You are losing a protection against MITM attacks by doing so. For a correct solution, see Paramiko "Unknown Server" .

Answer 2

The issue is that I was trying to utilize 3 input commands to change the password for root. I only needed to call the passwd command and then pass two input variables for "Enter new PW" and "Confirm new PW"

import paramiko
import time

hostname = 'IP'
username = 'root'
password = 'oldpw'


commands = ['passwd']



# initialize the SSH clientp
client = paramiko.SSHClient()
# add to known hosts
client.set_missing_host_key_policy(paramiko.AutoAddPolicy())
try:
    client.connect(hostname=hostname, username=username, password=password)
except:
    print("[!] Cannot connect to the SSH Server")
    exit()

# execute the commands
for command in commands:
    print("="*50, 'PW change executed', "="*50)
    stdin, stdout, stderr = client.exec_command(command)
    stdin.write('newpw' '\n' 'newpw' '\n') #input varuables for "Enter new PW" and "re-enter new PW"
    stdin.flush()
    print(stdout.read().decode())
    err = stderr.read().decode()
    if err:
        print(err)

Answer 3

trying the same but with the sudo command. without any success