Frontier Modem config key brute forcer

#!/usr/bin/env python
import telnetlib
import getpass

ip = "192.168.1.1"
prompt = "Wireless Broadband Router> " # Notice the tailing space!


print "Assuming IP is " + ip + ". Edit this script to change that"
print "First I'll need a username and password for the modem"
user = raw_input("Username: ")
passwd = getpass.getpass("Password: ")

tn = telnetlib.Telnet(ip)
tn.read_until("Username: ")
tn.write(user + "\n")
tn.read_until("Password: ")
tn.write(passwd + "\n")
print tn.read_until(prompt)
print "Logged in. Initing teh lulz"

characterset = list("abcdefghijklmnopqrstuvwxyz") # Starting with just lower case letters. caps, numbers and symbols are all possible
path = [0]

def increment(path):
    dbg("Incrementing " + str(path))
    done = False
    position = len(path)-1
    while not done:
        if path[position] == len(characterset)-1:
            dbg("Incrimenting character " + str(position))
            if position == 0:
                path[position] = 0
                path.append(0)
                done = True
                print "Increasing to " + str(len(path)) + " characters"
            else:
                path[position] = 0
                position = position-1
        else:
            path[position] = path[position] + 1
            done = True
    return path

def dbg(msg):
    if False:       # Change this to True to see debug messages
        print "DEBUG: " + msg

while True:     # Infinite loops are fun!
    textpath = "/"
    for char in path:
        textpath = textpath + characterset[char]
    dbg("Trying " + textpath)
    tn.write("conf print " + textpath + "\n")
    returned = tn.read_until(prompt)
    #print "> " + returned
    length = len(returned.split("\n"))
    if length != 4:
        print textpath + " returned " + str(length) + " lines"
    path = increment(path)