I'm using a 3 hop SSH with netmiko in Python and it does not like switching between the 2nd and 3rd hops

Question

My topology is: Laptop -> 1st Jumphost (my company) -> 2nd jumphost (my clients company) -> Various network devices (my clients network devices).

The network devices are only accessible from the 2nd jumphost, and the 2nd jumphost is only accessible from the 1st jumphost. So I'm using netmiko in Python to achieve this. My code is below.

The 1st block of code SSH's to the 1st jumphost, and then from there SSH's to the 2nd jumphost. This works correctly.

The 2nd block of code then opens a text file containing the hostnames or IP's of the individual network devices that need to be queried. For each host in that file, it SSH's to it, issues the "show version" command and then disconnects from the device (using "exit") so that the session is returned to the 2nd jumphost, ready for the next device in the file.

This works correctly for the very first device, but crashes upon the "output = device.send_command('exit')" line. Netmiko claims that the pattern is not detected. I think I understand why, because netmiko is using the name in the hostname prompt, when this changes back to the 2nd jumphost hostname upon the disconnect it gets confused and throws an error. If this is the case I have 2 questions:

1. How come it copes OK when moving from the 1st jumphost to the 2nd jumphost AND from the 2nd jumphost to the network device. In both of these cases the hostname prompt also changes...

2. What's the solution? How can I safely move between the 2nd jumphost and network devices in order to achieve the loop?

from netmiko import ConnectHandler
import time 

jump1 = "x.x.x.x"
jump2 = "y.y.y.y"
jump1_username = "myusername"
jump1_password = "mypassword"
jump2_username = "myusername"
jump2_password = "mypassword"
jump_type = "linux" 
cmd_jump = "ssh " + jump2_username + "@" + jump2 + "\n" 

device = ConnectHandler(device_type=jump_type, ip=jump1, username=jump1_username, password=jump1_password) # ssh to 1st jumphost
output = device.send_command('cat /proc/sys/kernel/hostname') #just shows me that login worked
print(output, flush=True) # just shows me that login worked
device.write_channel(cmd_jump) # enters ssh command for 2nd jumphost
time.sleep(1)
device.write_channel(jump2_password + "\n") # enters password for 2nd jumphost
time.sleep(1)
output = device.send_command('cat /proc/sys/kernel/hostname') #just shows me that second login worked
print(output, flush=True) # just shows me that second login worked

host_list = open(r'C:\device_list.txt','r') # a simple list of IP addresses you want to connect to each one on a new line

for host in host_list: # loop through network devices
    host = host.strip()
    cmd_device = "ssh " + host
    device.write_channel(cmd_device + "\n") # ssh to each device
    time.sleep(1)
    device.write_channel(jump2_password + "\n") # enter ssh password (credientals are the same as the 2nd jumphost)
    time.sleep(1)
    output = device.send_command('sh ver') # run show version command
    print(output, flush=True)
    output = device.send_command('exit') ' disconnect from network device to return to the 2nd jumphost
    time.sleep(1)
    print(output, flush=True)

Answer 1

Ignore me, I've solved my own problem. It's because I wasn't using the "write_channel" to enter the 'exit' command. Doh!