netscout

A fast, concurrent TCP port scanner built in Go. Scan single hosts or entire CIDR ranges with configurable worker pools, rate limiting, and multiple output formats.

Features

• Concurrent scanning — configurable worker pool (up to 10,000 goroutines)
• CIDR support — expand 192.168.1.0/24 into individual host scans
• Flexible port specs — single ports (80), lists (80,443), and ranges (8000-9000)
• Rate limiting — cap requests per second to avoid flooding
• Multiple output formats — text, JSON, CSV
• Graceful shutdown — handles SIGINT/SIGTERM cleanly
• Progress reporting — real-time scan rate and completion percentage
• Cross-platform — builds for Linux, macOS (Intel + Apple Silicon), and Windows

Installation

From source

git clone https://github.com/JeffreyOmoakah/netscout.git
cd netscout
make build

The binary will be at bin/netscout.

Go install

go install github.com/JeffreyOmoakah/netscout.git/cmd/netscout@latest

Usage

netscout -t <target> [options]

Flags

Flag	Default	Description
-t	(required)	Target IP or CIDR range (comma-separated)
-p	80,443	Ports to scan (e.g. 80,443 or 1-1024)
-w	100	Number of concurrent workers
-timeout	2s	Connection timeout
-rate	0	Rate limit in requests/sec (0 = unlimited)
-o	stdout	Output file path
-f	text	Output format: text, json, csv
-v	false	Verbose output with progress
-version		Print version and exit

Examples

Scan common ports on a single host:

netscout -t 192.168.1.1 -p 22,80,443,8080

Scan an entire subnet with verbose output:

netscout -t 10.0.0.0/24 -p 80,443 -v

Scan a port range, rate-limited, output to JSON:

netscout -t 192.168.1.1 -p 1-1024 -rate 500 -f json -o results.json

Scan with more workers and a longer timeout:

netscout -t 10.0.0.0/24 -p 22,80,443,3306,5432,8080 -w 500 -timeout 5s -v

Project Structure

netscout/
├── cmd/netscout/          # CLI entrypoint
│   └── main.go
├── internal/
│   ├── config/            # Configuration and validation
│   ├── parser/            # IP/CIDR and port parsing
│   ├── result/            # Result collection and output formatting
│   ├── scanner/           # Scan orchestration and progress reporting
│   └── worker/            # Worker pool and TCP connect scanning
├── Makefile
└── go.mod

Development

make build       # Build the binary
make run         # Build and run with example args
make dev         # Build and run in dev mode (verbose, more ports)
make test        # Run tests
make fmt         # Format code
make vet         # Run go vet
make build-all   # Cross-compile for linux/darwin/windows
make clean       # Remove build artifacts

License

This project is open source. See the repository for license details.