Port Scanner

A lightweight TCP port scanner written in Go.

This tool scans a target host (IP or domain) across a single port or range of ports using concurrent workers, then prints discovered open ports.

Features

• TCP connect scan using net.DialTimeout
• Configurable target host
• Supports single port (80) or range (1-1024)
• Configurable concurrency via worker threads
• Real-time output for open ports

Requirements

• Go 1.20+ (module currently targets Go 1.24.2)

Run

From the project root:

go run .

Default behavior:

• Host: 127.0.0.1
• Ports: 1-1024
• Threads: 100

CLI Options

Flag	Description	Default
-host	Target IP or domain (example: scanme.nmap.org)	127.0.0.1
-ports	Port range (1-1024) or single port (80)	1-1024
-threads	Number of concurrent workers	100

Examples

Scan default localhost range:

go run .

Scan a specific host and common ports:

go run . -host scanme.nmap.org -ports 20-100

Scan one port only:

go run . -host 192.168.1.10 -ports 22

Increase concurrency:

go run . -host example.com -ports 1-5000 -threads 300

Example Output

Scanning 127.0.0.1 on ports 1 to 1024 using 100 threads...
Port 22 is OPEN on 127.0.0.1
Port 80 is OPEN on 127.0.0.1
Scan complete! Open ports: [22 80]

Notes

• Only scans TCP ports.
• Port discovery order may vary because scanning is concurrent.
• Very high thread counts can increase CPU/network load.

Disclaimer

Use this tool only on systems you own or have explicit permission to test.