#!/bin/bash
destination_ip="${1:-1.1.1.1}"

# Set initial packet size
packet_size=1200

# Loop to find the maximum MTU size
while true; do
  ping -4 -M do -c 1 -s $packet_size $destination_ip &> /dev/null
  if [ $? -ne 0 ]; then
    echo "Maximum MTU size: $((packet_size + 28 - 2))"
    break
  fi
  packet_size=$((packet_size + 2))
done