[python]Connect to cisco ASA with pyserial

So on previous post I wrote a simple code to test if the serial com port is working, now I extended the code with some function.

I create a class for the serial so that more than one object can be created not just for a single Cisco ASA. The below code snippet gave a simple illustration on how to extend the feature with pyserial.

console.py

from serial import Serial
from serial.serialutil import SerialException
from time import sleep
import re

class Console():
    '''
    https://www.cisco.com/c/en/us/support/docs/dial-access/asynchronous-connections/9321-terminal-settings.html
    '''
    def __init__(self, com_port, device_type):
        self.com_port = com_port
        self.device_type = device_type

    def test_port(self):
        try:
            Serial(port=self.com_port)
            # returns a tuple, one is the boolean the other is whether error is None or not.
            return True, None
        except SerialException as e:
            return False, e

    def show_version(self):
        with Serial(port=self.com_port) as console:
            # press enter.
            console.write(b'\n')
            # serial is slow, need to wait for data to be transmitted.
            sleep(1)
            # assume no enable password, in practical this will fail.
            # always remember to include \n for hitting the enter key
            console.write(b'enable\n')
            sleep(1)
            # assume no password, press enter.
            # this is so manual... more logic has to be written.
            console.write(b'\n')
            sleep(1)
            # issue terminal pager 0 command so that all information will be presented
            # else need to press enter until the end of file.
            if self.device_type == 'cisco_asa':
                console.write(b'terminal pager 0\n')
                sleep(1)
            # this is the show version.
            console.write(b'show version\n')
            # this is estimated time to wait for the output to finish.
            sleep(3)
            # the return value is a byte.
            # get all the stream of bytes
            output_in_bytes = console.inWaiting()
            # read the collected byte stream
            show_version_output = console.read(output_in_bytes)
            # convert bytes to string.
            return show_version_output.decode('utf-8')

The test code is:

from console import Console

if __name__ == '__main__':
    cisco_fw = Console('com4', 'cisco_asa')
    status, err = cisco_fw.test_port()
    if status:
        output = cisco_fw.show_version()
        print(output)
    elif not status:
        print(err)

Future improvement of the code is to use pexpect module to check for the expected prompt in order to apply the correct commands.

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