Python Port Scanner

A simple TCP port scanner written in Python, built while learning networking and cybersecurity fundamentals.

What it does

Given an IP address or hostname and a port range, the script checks each port by attempting a TCP connection, and reports which ones are open.

Requirements

No third-party packages — uses only Python's built-in socket and time modules.

Usage

python scanner.py

You'll be prompted for:

• Target IP address or hostname (e.g. 127.0.0.1 or scanme.nmap.org)
• Start port (defaults to 1 if left blank)
• End port (defaults to 1024 if left blank)

Example output

Enter IP address or hostname: scanme.nmap.org
Start port (default 1): 20
End port (default 1024): 100

Scanning scanme.nmap.org (45.33.32.156) — ports 20-100...

Port 22 is OPEN
Port 80 is OPEN

Scan complete in 12.3 seconds.
Open ports: [22, 80]

What I learned

• How the socket module works for TCP connections
• The basics of ports and how connect-scanning works
• Handling bad input (unresolvable hostnames, invalid ranges) without crashing

Possible future improvements

• Multi-threading to scan faster
• Banner grabbing to identify the service running on each open port
• Export results to a file (CSV/JSON)
• Command-line arguments instead of interactive prompts

Disclaimer

This tool is for educational purposes only. Only scan hosts and networks you own or have explicit permission to test. Unauthorized port scanning may be illegal in your jurisdiction.