#!/bin/bash

# Define the port to listen on
PORT=12345

# Start an infinite loop to listen for incoming connections
while true; do
  # Use netstat to determine the IP address of the sender
  SENDER_IP=$(netstat -tn 2>/dev/null | awk '/'"$PORT"'/ {print $5}' | cut -d: -f1 | head -n1)

  # Listen on the specified port and capture the input without DNS lookups
  INPUT=$(nc -l -p $PORT)

  # Print debugging information
  echo "Received input: $INPUT"
  echo "Sender's IP address: $SENDER_IP"

  # Check if the received input matches the expected inputs
  case "$INPUT" in
    "Hello")
      # Send the response message back to the sender
      echo "World" | nc -q 0 $SENDER_IP $PORT
      ;;
    "Goodbye")
      # Send the response message back to the sender
      echo "Farewell" | nc -q 0 $SENDER_IP $PORT
      ;;
    *)
      # Send an unrecognized input message
      echo "Unrecognized input" | nc -q 0 $SENDER_IP $PORT
      ;;
  esac
done