Automating an un-automatable network switch required some creative programming. Create an SSH session inside a pseudo terminal (pty), then read and write the file descriptor.

pty_ssh.py

#!/usr/bin/python3

import argparse
import getpass
import os
import pty
import re
import sys
import time

commands_iterator = None
logfile = None
ssh_password = None

def interact(fd):
    """ The function that operates on the pty session's file descriptor. """
    password_pattern = b"(.+)@(.+)'s password: "
    prompt_pattern = b"[$#>]\s+$"
  
    # The spawn command recommends reading 1024 bytes at a time.
    data = os.read(fd, 1024)
  
    if re.search(password_pattern, data):
      # The ssh password prompt signature found, write the password.
      os.write(fd, (ssh_password + "\n").encode("utf-8"))
    elif re.search(prompt_pattern, data):
      # The prompt signature was found, write the next command.
      os.write(fd, next(commands_iterator).encode("utf-8"))
  
    if logfile:
      logfile.write(data)
      logfile.flush()
 
    return data

def main():
    """ The main function makes this script an applicaiton. """
    parser = argparse.ArgumentParser(description="Use a pseudo terminal (pty) to run a list of commands via ssh.")
    parser.add_argument("-u", "--user", help="the user to use for ssh")
    parser.add_argument("-a", "--address", help="the host address to ssh to")
    parser.add_argument("-p", "--password", help="the ssh password to use")
    parser.add_argument("file", help="the path to the file of commands")
    args = parser.parse_args()
    
    if not os.path.isfile(args.file):
        print("The path to the commands file does not exist.")
        exit(-1)
    
    with open(args.file) as commands_file:
        global command_iterator
        commands_iterator = iter(commands_file.readlines())
    
    logfilename = "{0}.log".format(os.path.splitext(args.file)[0])
    global logfile
    logfile = open(logfilename, "ab")
    
    global ssh_password
    if args.password:
        ssh_password = args.password
    else:
        ssh_password = getpass.getpass()
    
    ssh = [
        "ssh",
        "-o StrictHostKeyChecking=no",
        "{0}@{1}".format(args.user, args.address)
    ]
    
    # Spawn a new ssh session within a pty, the interact function will read and write to the file descriptor.
    pty.spawn(ssh, interact)

    print("{0} completed successfully.".format(sys.argv[0]))
    sys.exit(0)
    
if __name__ == "__main__":
    main()