Python ssh passphrase dictionary bruteforce

ssh_passphrase_bruteforce.py

import subprocess
import sys

def main():
	dictionary = sys.argv[1]
	with open(dictionary, "r") as dic:
		for line in dic:
			word = line.rstrip('\n')
			stdout = subprocess.call(
				'ssh-keygen -c -C "user@server" -P "{0}" -f "./id_rsa"'.format(word), 
				stderr=subprocess.DEVNULL, 
				stdout=subprocess.DEVNULL, 
				shell=True
			)
			if stdout == 0:
				print("Password found: " + word)
				return
	print("Password not found.")

if __name__ == "__main__":
	if len(sys.argv) == 2:
		main()
	else:
		print("missing args")