r-lanlib

A Rust library crate for performing network scanning operations on any local area network (LAN). This is the Rust version of the go-lanscan package.

Features

• ARP Scanning: Discover devices on your network using Address Resolution Protocol
• SYN Scanning: Detect open ports on discovered devices using TCP SYN packets
• Full Scanning: Combined ARP and SYN scanning in a single operation
• Vendor Detection: Identify device manufacturers using MAC address lookup
• Hostname Resolution: Resolve hostnames for discovered devices
• Async Communication: Channel-based communication for real-time scan results
• Flexible Targeting: Support for CIDR blocks, IP ranges, and port ranges

Requirements

• Root privileges required: This library performs raw packet operations that require elevated permissions
• Rust 1.89.0+ with 2024 edition support

Installation

cargo add r-lanlib

Quick Start

Basic ARP Scanning

use std::{sync::mpsc, time::Duration};
use r_lanlib::{
    network, packet,
    scanners::{
        arp_scanner::{ARPScanner, ARPScannerArgs},
        Device, ScanMessage, Scanner,
    },
    targets::ips::IPTargets,
};

// Get default network interface
let interface = network::get_default_interface()
    .expect("Cannot find network interface");

// Create packet wire (reader/sender)
let wire = packet::wire::default(&interface)
    .expect("Failed to create packet wire");

// Define IP targets (scan entire subnet)
let ip_targets = IPTargets::new(vec![interface.cidr.clone()]);

// Create communication channel
let (tx, rx) = mpsc::channel::<ScanMessage>();

// Configure scanner
let scanner = ARPScanner::new(ARPScannerArgs {
    interface: &interface,
    packet_reader: wire.0,
    packet_sender: wire.1,
    targets: ip_targets,
    source_port: 54321,
    include_vendor: true,
    include_host_names: true,
    idle_timeout: Duration::from_millis(10000),
    notifier: tx,
});

// Start scanning (runs in background thread)
let handle = scanner.scan();

// Process results in real-time
let mut devices = Vec::new();
loop {
    match rx.recv().expect("Failed to receive message") {
        ScanMessage::Done => break,
        ScanMessage::ARPScanResult(device) => {
            println!("Found device: {} ({})", device.ip, device.hostname);
            devices.push(device);
        }
        ScanMessage::Info(scanning) => {
            println!("Scanning: {}", scanning.ip);
        }
    }
}

handle.join().expect("Scanner thread failed");
println!("Discovered {} devices", devices.len());

SYN Port Scanning

use r_lanlib::{
    scanners::{
        syn_scanner::{SYNScanner, SYNScannerArgs},
        Device, SYNScanResult, Scanner,
    },
    targets::ports::PortTargets,
};

// Define target devices (from previous ARP scan or manual)
let devices = vec![
    Device {
        hostname: "router".to_string(),
        ip: "192.168.1.1".to_string(),
        mac: "aa:bb:cc:dd:ee:ff".to_string(),
        vendor: "".to_string(),
        is_current_host: false,
    }
];

// Define port targets
let port_targets = PortTargets::new(vec![
    "22".to_string(),      // SSH
    "80".to_string(),      // HTTP
    "443".to_string(),     // HTTPS
    "8000-9000".to_string(), // Port range
]);

let scanner = SYNScanner::new(SYNScannerArgs {
    interface: &interface,
    packet_reader: wire.0,
    packet_sender: wire.1,
    targets: devices,
    ports: port_targets,
    source_port: 54321,
    idle_timeout: Duration::from_millis(10000),
    notifier: tx,
});

// Process SYN scan results
let mut results = Vec::new();
let handle = scanner.scan();

loop {
    match rx.recv().expect("Failed to receive message") {
        ScanMessage::Done => break,
        ScanMessage::SYNScanResult(result) => {
            println!("Open port {} on {}",
                result.open_port.id,
                result.device.ip
            );
            results.push(result);
        }
        _ => {}
    }
}

Full Scanning (ARP + SYN)

use r_lanlib::scanners::{
    full_scanner::{FullScanner, FullScannerArgs},
    Scanner,
};

let scanner = FullScanner::new(FullScannerArgs {
    interface: &interface,
    packet_reader: wire.0,
    packet_sender: wire.1,
    targets: ip_targets,
    ports: port_targets,
    include_vendor: true,
    include_host_names: true,
    idle_timeout: Duration::from_millis(10000),
    notifier: tx,
    source_port: 54321,
});

// This will perform ARP discovery first, then SYN scan on found devices
let handle = scanner.scan();

API Reference

Core Modules

network

Provides helpers for selecting network interfaces:

• get_default_interface() - Get the default network interface
• get_interface(name) - Get a specific interface by name
• get_available_port() - Find an available port for scanning

packet

Low-level packet creation and transmission:

• wire::default(interface) - Create default packet reader/sender pair
• Various packet builders for ARP, SYN, RST packets

scanners

Main scanning implementations:

• ARPScanner - Discover devices using ARP
• SYNScanner - Scan ports on known devices
• FullScanner - Combined ARP + SYN scanning

targets

Target specification utilities:

• ips::IPTargets - Define IP ranges and CIDR blocks
• ports::PortTargets - Define port ranges and individual ports

Data Structures

Device

Represents a discovered network device:

pub struct Device {
    pub hostname: String,
    pub ip: String,
    pub mac: String,
    pub vendor: String,
    pub is_current_host: bool,
}

Port

Represents a network port:

pub struct Port {
    pub id: u16,
    pub service: String,
}

SYNScanResult

Result of a SYN scan operation:

pub struct SYNScanResult {
    pub device: Device,
    pub open_port: Port,
}

ScanMessage

Messages sent over the notification channel:

pub enum ScanMessage {
    Done,                           // Scanning complete
    Info(Scanning),                 // Status update
    ARPScanResult(Device),          // ARP discovery result
    SYNScanResult(SYNScanResult),   // SYN scan result
}

Target Specification

IP Targets

// CIDR blocks
IPTargets::new(vec!["192.168.1.0/24".to_string()]);

// IP ranges
IPTargets::new(vec!["192.168.1.1-192.168.1.100".to_string()]);

// Individual IPs
IPTargets::new(vec!["192.168.1.1".to_string(), "10.0.0.1".to_string()]);

Port Targets

// Port ranges
PortTargets::new(vec!["1-1000".to_string()]);

// Individual ports
PortTargets::new(vec!["22".to_string(), "80".to_string(), "443".to_string()]);

// Mixed specification
PortTargets::new(vec![
    "22".to_string(),
    "80".to_string(),
    "8000-9000".to_string()
]);

Examples

The library includes several complete examples in the examples/ directory:

• arp-scanner.rs - Basic ARP device discovery
• syn-scanner.rs - Port scanning on known devices
• full-scanner.rs - Complete network reconnaissance

Run examples from the workspace root with:

sudo -E cargo run --example arp-scanner -p r-lanlib
sudo -E cargo run --example syn-scanner -p r-lanlib
sudo -E cargo run --example full-scanner -p r-lanlib

Configuration Options

Scanner Timeouts

• idle_timeout - How long to wait for responses before concluding scan
• Default: 10 seconds (10,000ms)
• Recommended: 5-30 seconds depending on network size and latency

Scanner Features

• include_vendor - Perform MAC address vendor lookup using IEEE OUI database
• include_host_names - Resolve hostnames via reverse DNS lookup
• source_port - Source port for scan packets (auto-selected if not specified)

Performance Tuning

• Concurrent scanning: Multiple threads handle packet I/O for optimal throughput
• Memory efficiency: Zero-copy packet processing where possible
• Network-aware: Automatic rate limiting to prevent network congestion
• Timeout optimization: Adaptive timeouts based on network response times

Security Considerations

• Requires root privileges for raw socket access on Unix-like systems
• Network scanning may be restricted by network policies and firewalls
• Built-in rate limiting prevents network congestion and reduces detection risk
• Minimal network footprint: Optimized packet sizes and timing
• Memory safety: Rust's ownership system prevents buffer overflows and memory corruption
• Use responsibly and only on networks you own or have permission to scan
• Logging: All scan activities can be logged for audit purposes

Ethical Usage Guidelines

• Always obtain proper authorization before scanning
• Respect network resources and avoid aggressive scanning
• Be aware that scanning activities may be logged by network security systems
• Consider the impact on network performance during large-scale scans

Error Handling

The library uses ScanError for comprehensive error reporting:

pub struct ScanError {
    pub ip: Option<String>,
    pub port: Option<String>,
    pub error: Box<dyn Error>,
}

All scanner operations return Result<(), ScanError> for proper error handling.

License

This project is dual-licensed under either of

• Apache License, Version 2.0 (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
• MIT License (LICENSE-MIT or http://opensource.org/licenses/MIT)

at your option.

Related Projects

• go-lanscan - Original Go implementation
• r-lancli - Command-line interface using this library
• r-lanterm - Terminal UI application using this library