Break function not working on python Cisco factory reset script

Question

import serial
import time

# Serial port configuration
ser = serial.Serial("/dev/ttyUSB0", timeout=1)
print(f"Connecting to {ser.name}...")

# Strings for prompt detection
initPrompt = "Initializing Flash"
swPrompt = "switch:"
ynPrompt = " (y/n)?"

# Function to wait for specific prompt and send command
def wait_for_prompt_and_send(prompt, command):
    while True:
        response = ser.read_until(prompt.encode("utf-8")).decode("utf-8")
        if prompt in response:
            print(f"Found prompt: {prompt}")
            ser.write(command)
            ser.write(b"\n")
            break

# Connect and send initial break commands
ser.write(b"\r")
print("Sent carriage return...")
time.sleep(0.5)
wait_for_prompt_and_send(initPrompt, b"\x03")  # break command

# Initialize flash
wait_for_prompt_and_send(swPrompt, b"flash_init\n\n")

# Delete vlan.dat
wait_for_prompt_and_send(swPrompt, b"del flash:vlan.dat\n")
wait_for_prompt_and_send(ynPrompt, b"y\n")

# Delete config.text
wait_for_prompt_and_send(swPrompt, b"del flash:config.text\n")
wait_for_prompt_and_send(ynPrompt, b"y\n")`

ser.close()

I have to reset alot of old Cisco switches so I wanted to automate the process.

Instead of holding down the physical button on the switch, the script should issue a break command after the programm ran the initPrompt initializing flash. However, it doesn't do that. All I see on the python console is that it sent the carriage return and found the prompt: initializing flash. When I open the SecureCRT session and check the status of the startup, the switch goes through the normal boot so the break definitly didn't work.

Win 10 & Python 3.10

what are you expecting the break to do? it seems like the break would allow your script to continue to the next wait_for_prompt_and_send call — Anentropic
– Anentropic, Commented Aug 16, 2023 at 10:19
the break is to stop the boot process so it goes into the password recovery mode where the switch: prompt shows up. Kinda like pushing the button — Sebastian Buergi
– Sebastian Buergi, Commented Aug 16, 2023 at 11:09
how does the break stop the boot process? in this code it breaks out of the while True loop, allowing the function to return — Anentropic
– Anentropic, Commented Aug 16, 2023 at 11:12
Does it not? Thats how I learned it to, insert the b"\x03". In that case would there be another command to force the switch to go into the switch: menu instead of the login menu? — Sebastian Buergi
– Sebastian Buergi, Commented Aug 16, 2023 at 11:15
I see, I was talking about the Python break but you are talking about sending b"\x03" command. In that case I have no idea, but sounds like maybe that is not the right command sequence? Something specific to Cisco router anyway — Anentropic
– Anentropic, Commented Aug 16, 2023 at 11:22

Shahab Rahnama · Accepted Answer · 2023-08-28 20:24:01Z

0

Looking at the docs, you could try the send_break(duration=0.25) parameter and maybe play around a bit with the duration value.

edited Aug 28, 2023 at 20:24

Shahab Rahnama

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answered Aug 24, 2023 at 17:55

Max Kommern

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Comments

Mike Pennington · Accepted Answer · 2024-07-15 17:35:05Z

0

Your timeout appears to be too short to detect the Initializing Flash prompt

ser = serial.Serial("/dev/ttyUSB0", timeout=1)

1-second barely gives the router enough time to start the init sequence... you need to make it longer, such as 15-seconds

answered Jul 15, 2024 at 17:35

Mike Pennington

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