passwd_gen.py

#!/usr/bin/env python

import string
import random
import hashlib
import fileinput
import os

# function to generate a random password of 12 characters, using upper/lowercase letters,
# digits, and a small group of punctuation characters.
# can change size by passing number - i.e. pass_generator(6)
def pass_generator(size=12, chars=string.letters + string.digits + '!%&*-+<>'):
	# using random.SystemRandom().choice() instead of random.choice() uses /dev/urandom.
	# this is a cryptographically secure PRNG (pseudorandom number generator).
	return ''.join(random.SystemRandom().choice(chars) for _ in range(size))

def grub_conf(grub_passwd):
	grub_md5 = hashlib.md5(grub_passwd).hexdigest()

	pass_line = 'password --md5 %s' % grub_md5

	processing_lines = False
	for line in fileinput.input('/boot/grub/grub.conf', inplace=1):
		if line.startswith('default=0'):
			processing_lines = True
		else:
			if processing_lines:
				print pass_line
			processing_lines = False
		print line,

def passwd_file(root_passwd, grub_passwd):
	f = open('/root/.password', 'w')
	content = 'root %s\ngrub %s\n' % \
				(root_passwd, grub_passwd)
	f.write(content)
	f.close

def change_passwd(root_passwd):
	# bash command for changing root password
	os.system('echo "%s" | passwd --stdin root' % root_passwd)

def main():
	# collect the root and grub passwords
	root_passwd = pass_generator()
	grub_passwd = pass_generator()

	# enter the md5 hash of grub password into /boot/grub/grub.conf
	grub_conf(grub_passwd)

	# write the passwords to .password file
	# will overwrite if file exists
	passwd_file(root_passwd, grub_passwd)

	# change the root password
	change_passwd(root_passwd)

	print '''
	The root and grub passwords have been set.

		root %s
		grub %s

	See /root/.password for details.
	''' % (root_passwd, grub_passwd)

	finished = ''
	finished = raw_input('Please make a note of the root password then press "y": ')

	while True:
		if finished != 'y':
			continue
		else:
			break

if __name__ == '__main__':
	try:
		main()
	except Exception, e:
		print str(e)