googlebot_checker.sh

#!/bin/sh

ips=(
66.249.71.9
66.249.71.8
66.249.71.7
66.249.66.89
66.249.66.88
66.249.66.78
66.249.66.69
66.249.66.68
)

for ip in "${ips[@]}"; do
  echo "ip: $ip"
  HOSTNAME=$(host "$ip" | awk '/domain name pointer/ {print $5}' | sed 's/\.$//')
  echo "Resolved hostname: $HOSTNAME"

  # check if the hostname belongs to googlebot.com or google.com
  if [[ "$HOSTNAME" =~ .*\.google(bot)?\.com$ ]]; then
    # get IP address from host name by forward lookup
    REVERSED_IP=$(host "$HOSTNAME" | awk '/has address/ {print $4}')

    # check if the forward lookup result matches the original IP
    if [[ "$REVERSED_IP" == "$ip" ]]; then
      echo "$ip is a verified Googlebot"
    else
      echo "$ip resolved to $HOSTNAME, but forward resolution does not match. Not a Googlebot."
      exit 1
    fi
  else
    echo "$ip is NOT a Googlebot"
    exit 1
  fi
done