This code has been tested on Ubuntu.
To start it, you need to open two terminals (on PowerShell), one for the server and one for the client.

python3 .\main.py

telnet <ip> <port>

All of those packages are needed to run the code :

• os (OS)
• sys (System)
• arrow (Date and time)
• socket (Socket)
• subprocess (Run commands)
• threading (for multi-threading)
• json (JSON)
• hashlib (Hashing)
• prctl (Process control for Linux)
• jsonschema (JSON Schema validation)
• ctypes (Ctypes)

• v - to toggle verbose mode (less/more output)
• c - to change server's time
• q - to quit
• t - to get the time
• h - to get help

• c - to change the time format
• q - to quit
• t - to get the time
• h - to get help

• Removed outputs and logs in admin mode
• Added capabilites with prctl
• Removed datetime.strftime and replaced it with arrow (more efficient and secure : https://snyk.io/advisor/python/arrow)
• Removed validate_time_format()
• Fixed the decoding of inputs, 1024 bytes instead of 1
• Time isn't send every second anymore but on request
• Added administrative privileges in change_time()
• Added full path and hash check when calling time_changer.py
• Removed regexp in validate_format()
• Removed get_hours_minutes_seconds() and get_day_month_year()
• Removed send_message_to_clients() and print_message_to_clients()
• Removed prompt_mode_selection() and starting both offline and online mode at the same time
• Added config.json

Arrow is way more efficient than datetime, it's also more secure.
Used multiple scan tools such as Snyk and Bandit to check for vulnerabilities.
Arrow is also more efficient in terms of code, it's way more readable and easier to use.

• Changed the way of changing the time
• Calling secure_execution() earlier
• Added DEP
• Added full path and hash check when calling config.json
• Revoked privileges in main.py
• Removed sys.exit(1) in secure_execution()
• Removed sys.exit(1) in change_time()
• Updated receive_data() to read chunks of data instead of pieces of text
• Added jsonschema to validate config.json

• Removed sys.exit(1) in secure_execution() in main.py
• Reworked handle_client_connection() to use receive_data() instead of select
• Removed select in imports