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#!/usr/bin/env python3
import socket
import ssl
import time
import argparse
import sys
import os
HEADER_LENGTH = 64
KEY_LENGTH = 64
DISCONNECT_LENGTH = ACK_LENGTH = 3
ACK_MESSAGE = "ACK"
DISCONNECT_MESSAGE = "BYE"
FORMAT = "utf-8"
import configparser
def die(msg):
print(msg)
sys.exit(1)
def parse_arguments():
parser = argparse.ArgumentParser()
parser.add_argument("--server",type=str,help="IP of MFA Server")
parser.add_argument("--port",type=int,help="Port to connect to")
parser.add_argument("--config",type=str,help="Path to config file",\
default="/etc/mfa/mfa.conf")
parser.add_argument("--key",type=str,help="Client connection key")
parser.add_argument("--plain",action="store_true",help="Connect without TLS")
parser.add_argument("--insecure",action="store_true",\
help="Accept invalid TLS certificates")
return parser.parse_args()
def prompt_user(prompt):
# Prompt user for input and return input
print(prompt)
result = input("> ")
return result
def init_connection_tls(mfa_server, client_port, client_key, insecure=False):
# Attempts to connect to MFA server with provided address,port, and key.
# Repeats attempt once a seconds until timeout is reached.
# Returns socket or None if unable to connect
connection = None
timeout = 0
timeout_length = 5
sleep_length = 1
context = ssl.create_default_context()
if insecure:
context.check_hostname = False
context.verify_mode = 0
while connection == None and timeout < timeout_length:
try:
#connection = socket.create_connection((mfa_server,client_port))
connection = context.wrap_socket(socket.socket(socket.AF_INET),
server_hostname=mfa_server)
connection.connect((mfa_server,int(client_port)))
connection.send(client_key.encode(FORMAT))
response = connection.recv(ACK_LENGTH).decode(FORMAT)
if response == ACK_MESSAGE:
print("connected to mfa server")
elif response == DISCONNECT_MESSAGE:
print("server terminated connection")
sys.exit(1)
except ConnectionError:
time.sleep(sleep_length)
timeout += sleep_length
except ssl.SSLCertVerificationError:
die("error: server presented invalid certificate")
return connection
def init_connection(mfa_server, client_port, client_key):
connection = None
timeout = 0
timeout_length = 5
sleep_length = 1
while connection == None and timeout < timeout_length:
try:
connection = socket.create_connection((mfa_server,client_port))
connection.send(client_key.encode(FORMAT))
response = connection.recv(ACK_LENGTH).decode(FORMAT)
if response == ACK_MESSAGE:
print("connected to mfa server")
elif response == DISCONNECT_MESSAGE:
print("server terminated connection")
sys.exit(1)
except ConnectionError:
time.sleep(sleep_length)
timeout += sleep_length
return connection
def read_config(config_file):
parser = configparser.ConfigParser(inline_comment_prefixes="#")
parser.read(config_file)
return parser
def get_vars(args,confparser):
if not os.path.exists(args.config):
print("Unable to open config file")
sys.exit(1)
server = None
port = None
key = None
plain = None
insecure = None
# Set values from config file first
if confparser.has_section("client"):
server = confparser.get("client","server",fallback=None)
port = confparser.get("client","port",fallback=None)
key = confparser.get("client","key",fallback=None)
plain = confparser.get("client","plain",fallback=False)
insecure = confparser.get("client","insecure",fallback=False)
if plain.lower() == "false":
plain = False
if insecure.lower() == "false":
insecure = False
# Let command line args overwrite any values
if args.server != None:
server = args.server
if args.port != None:
port = args.port
if args.key != None:
key = args.key
if args.plain:
plain = args.plain
if args.insecure:
insecure = args.insecure
# Exit if any value is null
if None in [server,port,key]:
print("error: one or more items unspecified")
sys.exit(1)
return server,port,key,plain,insecure
def main():
# Get arguments, exit if unable to connect
args = parse_arguments()
confparser = read_config(args.config)
mfa_server,client_port,client_key,plain,insecure = get_vars(args,confparser)
# Exit if invalid key is provided
if len(client_key) != KEY_LENGTH:
print("invalid key")
sys.exit(1)
# Open connection to server
if plain:
conn = init_connection(mfa_server,client_port,client_key)
else:
conn = init_connection_tls(mfa_server,client_port,client_key,insecure)
if conn == None:
print("timed out attempting to connect to server")
sys.exit(1)
# Main loop
running = True
while running:
# Receive MFA prompt from server
header = conn.recv(HEADER_LENGTH).decode(FORMAT)
if header == "":
die("error: lost connection to server")
prompt_len = int(header)
prompt = conn.recv(prompt_len).decode(FORMAT)
# Ask user for response
answer = prompt_user(prompt)
# Send answer to MFA server
answer_length = len(answer)
length_msg = str(answer_length)
length_msg += ' ' * (HEADER_LENGTH - len(length_msg))
conn.send(length_msg.encode(FORMAT))
conn.send(answer.encode(FORMAT))
if __name__ == '__main__':
main()
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