chaos-query.sh

chaos-query.sh

#!/usr/bin/env bash
#
# chaos-query.sh - Query DNS servers using CHAOS class TXT records
# Author: Besmir Zaanaj
#
# Usage:
#   ./chaos-query.sh <dns_server_ip_or_name> [record]
#
# Examples:
#   ./chaos-query.sh 8.8.8.8
#   ./chaos-query.sh 1.1.1.1 version.bind
#   ./chaos-query.sh 9.9.9.9 id.server

set -euo pipefail

if ! command -v dig >/dev/null 2>&1; then
  echo "Error: dig not found in PATH" >&2
  exit 1
fi

if [[ $# -lt 1 ]]; then
  echo "Usage: $0 <dns_server> [record]" >&2
  exit 1
fi

DNS_SERVER="$1"
RECORD="${2:-all}"

# Helper to run a single CHAOS TXT query
chaos_query() {
  local name="$1"
  echo "=== ${name} @ ${DNS_SERVER} ==="
  dig +short -t TXT -c CHAOS "${name}" @"${DNS_SERVER}" || true
  echo
}

case "${RECORD}" in
  all)
    # Common CHAOS records supported by BIND/CoreDNS etc.
    chaos_query "version.bind"   # Software/version
    chaos_query "hostname.bind"  # Server hostname
    chaos_query "id.server"      # Anycast/instance ID
    chaos_query "authors.bind"   # software version generally
    ;;
  version.bind|hostname.bind|id.server|authors.bind)
    chaos_query "${RECORD}"
    ;;
  *)
    # Allow arbitrary CHAOS TXT name
    chaos_query "${RECORD}"
    ;;
esac