322 lines
14 KiB
Bash
Executable File
322 lines
14 KiB
Bash
Executable File
#!/usr/bin/env bash
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# Debian 13: switch system name resolution from systemd-resolved to local BIND9.
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# No package installation, BIND configuration or networking changes.
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set -Eeuo pipefail
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umask 077
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readonly STATE_DIR=/var/backups/oopen-bind9-direct-resolver
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readonly CURRENT_FILE="$STATE_DIR/current"
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readonly RESOLV=/etc/resolv.conf
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readonly NSS=/etc/nsswitch.conf
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readonly EXPECTED_NSS='hosts: files myhostname dns'
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MODE="${1:---check}"
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case "$MODE" in --check|--apply|--rollback|--repair-postfix|--help) ;; *) echo "Usage: $0 [--check|--apply|--rollback|--repair-postfix|--help]" >&2; exit 2;; esac
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# Colorize status labels on terminals; respect NO_COLOR and redirected output.
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if [[ -t 1 && ! -v NO_COLOR && "${TERM:-}" != dumb ]]; then
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GREEN=$'\033[32m'
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GREY=$'\033[90m'
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RED=$'\033[31m'
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YELLOW=$'\033[33m'
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RESET=$'\033[0m'
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else
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GREEN='' GREY='' RED='' YELLOW='' RESET=''
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fi
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info() { printf '[ Info ] %s\n' "$*"; }
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ok() { printf '%s[ ok ]%s %s\n' "$GREEN" "$RESET" "$*"; }
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skipped() { printf '%s[ skipped ]%s %s\n' "$GREY" "$RESET" "$*"; }
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failed() { printf '%s[ failed ]%s %s\n' "$RED" "$RESET" "$*" >&2; }
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# Delimited summary at the end of --check / before an interactive --apply.
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status_banner(){
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local color="$1" message="$2" detail="${3:-}"
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printf '\n%s------------------------------------------------------------%s\n' "$color" "$RESET"
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printf '%s%s%s\n' "$color" "$message" "$RESET"
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[[ -z "$detail" ]] || printf '%s%s%s\n' "$color" "$detail" "$RESET"
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printf '%s------------------------------------------------------------%s\n' "$color" "$RESET"
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}
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# Every invocation finishes with one additional empty output line.
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trap 'printf "\n"' EXIT
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fatal() { failed "$*"; exit 1; }
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echononl(){ printf '%-56s' "$*"; }
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require_root(){ [[ "${EUID}" -eq 0 ]] || fatal 'Please run as root.'; }
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need(){ command -v "$1" >/dev/null 2>&1 || fatal "Missing command: $1"; }
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confirm(){ local answer; read -r -p 'Einverstanden [yes/no, default: no]? ' answer || true; [[ "$answer" == yes ]]; }
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# Only this script's state file controls rollback. Older manual backups are untouched.
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# Each run's backup retains the exact file or symlink, along with active/enabled state.
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state_dir_from_marker(){
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[[ -f "$CURRENT_FILE" ]] || return 1
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local p
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IFS= read -r p < "$CURRENT_FILE" || true
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[[ "$p" == "$STATE_DIR"/run-* && -d "$p" && -f "$p/metadata" ]] || fatal 'Invalid resolver rollback marker.'
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printf '%s\n' "$p"
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}
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is_direct(){
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[[ -f "$RESOLV" && ! -L "$RESOLV" ]] &&
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[[ "$(awk '$1=="nameserver" {print $2}' "$RESOLV")" == '127.0.0.1' ]] &&
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grep -Eq '^[[:space:]]*hosts:[[:space:]]*files[[:space:]]+myhostname[[:space:]]+dns[[:space:]]*$' "$NSS"
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}
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is_fully_switched(){
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is_direct && ! systemctl is-active --quiet systemd-resolved &&
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[[ "$(systemctl is-enabled systemd-resolved 2>/dev/null || true)" == disabled ]]
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}
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# BIND must reject a known bogus signature, not merely answer normal queries.
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preflight(){
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echononl 'BIND9 on 127.0.0.1:53'
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if dig @127.0.0.1 oopen.de A +time=3 +tries=1 +short | grep -Eq '^[0-9]+\.[0-9]+\.[0-9]+\.[0-9]+$'; then ok 'reachable'; else echo; failed 'Local BIND9 does not resolve oopen.de'; return 1; fi
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echononl 'DNSSEC positive test (AD flag)'
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local reply
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reply=$(dig @127.0.0.1 cloudflare.com A +dnssec +adflag +time=5 +tries=1)
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if grep -q 'status: NOERROR' <<< "$reply" && grep -Eq 'flags:.*[[:space:]]ad[;[:space:]]' <<< "$reply"; then ok 'validated'; else echo; failed 'BIND9 DNSSEC positive test failed'; return 1; fi
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echononl 'DNSSEC negative test (SERVFAIL)'
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reply=$(dig @127.0.0.1 www.dnssec-failed.org A +time=5 +tries=1)
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if grep -q 'status: SERVFAIL' <<< "$reply"; then ok 'rejected as expected'; else echo; failed 'BIND9 does not reject invalid DNSSEC test zone'; return 1; fi
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}
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# Debian Postfix: systemd instance startup refreshes the chroot resolver files.
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# This is deliberately limited to running Postfix instances. No data_directory
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# files are ever removed. A queue flush remains a separate admin decision.
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postfix_units(){
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local unit
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while read -r unit _; do
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[[ "$unit" == postfix@*.service ]] || continue
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printf '%s\n' "$unit"
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done < <(systemctl list-units --type=service --state=active --no-legend --plain 'postfix@*.service' 2>/dev/null)
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}
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sync_postfix(){
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local -a units=()
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local unit queue_dir chroot_resolv
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if ! command -v postconf >/dev/null 2>&1; then
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skipped 'Postfix not installed; no MTA restart required'
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return 0
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fi
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mapfile -t units < <(postfix_units)
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if (( ${#units[@]} == 0 )); then
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if systemctl is-active --quiet postfix.service; then
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units=(postfix.service)
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else
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skipped 'No active Postfix service; no MTA restart required'
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return 0
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fi
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fi
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info 'Restarting active Postfix systemd service(s) to refresh chroot DNS'
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for unit in "${units[@]}"; do
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systemctl restart "$unit" || { failed "Postfix restart failed: $unit"; return 1; }
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if ! systemctl is-active --quiet "$unit"; then
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failed "Postfix service not active after restart: $unit"
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return 1
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fi
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ok "Postfix restarted: $unit"
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done
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# Only assert a chroot resolver copy when it exists; custom setups may
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# use multiple queue directories or run SMTP clients without chroot.
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queue_dir=$(postconf -h queue_directory 2>/dev/null || true)
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if [[ -n "$queue_dir" && -f "$queue_dir/etc/resolv.conf" ]]; then
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chroot_resolv="$queue_dir/etc/resolv.conf"
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if cmp -s "$RESOLV" "$chroot_resolv"; then
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ok "Postfix chroot resolver synchronized: $chroot_resolv"
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else
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failed "Postfix chroot resolver differs: $chroot_resolv"
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failed 'Check Debian postfix configure-instance.sh / active instances'
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return 1
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fi
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else
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info 'No default Postfix chroot resolv.conf found (possibly non-chroot or custom layout)'
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fi
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info 'Deferred mail is not flushed automatically; if appropriate run: postqueue -f'
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}
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show_check(){
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require_root
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need dig; need systemctl; need getent
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printf '\n=== DNS resolver status ===\n'
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printf 'resolv.conf: '; if [[ -L "$RESOLV" ]]; then readlink "$RESOLV"; else echo 'regular file'; fi
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grep -E '^[[:space:]]*(nameserver|search|options)[[:space:]]' "$RESOLV" || true
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grep -E '^hosts:' "$NSS" || true
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printf 'systemd-resolved active: %s\n' "$(systemctl is-active systemd-resolved 2>/dev/null || true)"
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printf 'systemd-resolved enabled: %s\n' "$(systemctl is-enabled systemd-resolved 2>/dev/null || true)"
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local readiness=0
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if preflight; then readiness=1; fi
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if is_fully_switched; then
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if (( readiness )); then
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status_banner "$GREY" 'Umstellung auf BIND9 bereits durchgeführt.'
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else
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status_banner "$YELLOW" 'Umstellung bereits durchgeführt, aber DNS-Prüfung fehlgeschlagen.'
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fi
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elif [[ -f "$CURRENT_FILE" ]]; then
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status_banner "$YELLOW" 'Umstellung kann nicht ausgeführt werden.' \
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'Ein vorheriger Rollback-Stand ist vorhanden; zunächst prüfen oder zurückbauen.'
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elif (( readiness )); then
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status_banner "$GREEN" 'Umstellung kann durchgeführt werden.' \
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"Ausführen mit: $0 --apply"
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else
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status_banner "$YELLOW" 'Umstellung kann nicht ausgeführt werden.' \
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'BIND9-/DNSSEC-Voraussetzungen nicht erfüllt; bitte Fehler prüfen.'
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fi
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if [[ -f "$CURRENT_FILE" ]]; then
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printf '\n=== Rollback information ===\n'
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info 'Backup from before the last --apply is available'
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info "Backup: $(state_dir_from_marker)"
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info "Restore with: $0 --rollback"
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fi
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}
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restore_files(){
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local path="$1"
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[[ -d "$path" && -e "$path/nsswitch.conf" ]] || fatal 'Incomplete backup: NSS'
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[[ -e "$path/resolv.conf" || -L "$path/resolv.conf" ]] || fatal 'Incomplete backup: resolv.conf'
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cp -a --remove-destination "$path/nsswitch.conf" "$NSS"
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cp -a --remove-destination "$path/resolv.conf" "$RESOLV"
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}
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restore_services(){
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local path="$1" enabled active
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enabled=$(sed -n 's/^resolved_enabled=//p' "$path/metadata")
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active=$(sed -n 's/^resolved_active=//p' "$path/metadata")
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case "$enabled" in
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enabled|enabled-runtime) systemctl enable systemd-resolved >/dev/null ;;
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disabled) systemctl disable systemd-resolved >/dev/null ;;
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static|indirect|masked|alias|'') info "Previous enabled state '$enabled'; no enable-state change" ;;
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*) info "Unrecognized previous enabled state '$enabled'; no enable-state change" ;;
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esac
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case "$active" in
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active) systemctl start systemd-resolved ;;
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inactive|failed) systemctl stop systemd-resolved ;;
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*) info "Previous active state '$active'; no service-state change" ;;
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esac
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}
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rollback_to(){
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local path="$1"
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info "Restoring config from $path"
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# Stop resolved first only when it was previously not active; otherwise start after files.
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restore_files "$path"
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restore_services "$path"
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ok 'Configuration and resolved service state restored'
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sync_postfix
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}
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apply(){
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require_root
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for cmd in dig getent systemctl cp mv mktemp grep awk sed date; do need "$cmd"; done
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[[ -f "$NSS" ]] || fatal "$NSS missing"
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[[ -e "$RESOLV" || -L "$RESOLV" ]] || fatal "$RESOLV missing"
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[[ ! -f "$CURRENT_FILE" ]] || {
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if is_fully_switched; then status_banner "$GREY" 'Umstellung auf BIND9 bereits durchgeführt.'; skipped 'No changes'; exit 0; fi
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status_banner "$YELLOW" 'Umstellung kann nicht ausgeführt werden.' 'Vorheriger Rollback-Stand vorhanden.'
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fatal 'An earlier script run has rollback state. Use --check or --rollback first.';
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}
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if is_fully_switched; then status_banner "$GREY" 'Umstellung auf BIND9 bereits durchgeführt.'; skipped 'No changes'; exit 0; fi
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info 'Preflight checks (no changes)'
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if ! preflight; then
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status_banner "$YELLOW" 'Umstellung kann nicht ausgeführt werden.' 'BIND9-/DNSSEC-Voraussetzungen nicht erfüllt.'
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return 1
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fi
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status_banner "$GREEN" 'Umstellung kann durchgeführt werden.' \
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"Ausführen mit: $0 --apply"
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printf '\nPlanned changes:\n hosts: files myhostname dns\n resolv.conf: nameserver 127.0.0.1\n stop and disable systemd-resolved\n'
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info 'Network interfaces, routes and BIND9 are unchanged; active Postfix will restart.'
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confirm || { skipped 'Abbruch durch User'; exit 0; }
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mkdir -p "$STATE_DIR"
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chmod 700 "$STATE_DIR"
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local path timestamp
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timestamp=$(date +%Y%m%d-%H%M%S)
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path=$(mktemp -d "$STATE_DIR/run-${timestamp}-XXXXXX")
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cp -a "$RESOLV" "$path/resolv.conf"
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cp -a "$NSS" "$path/nsswitch.conf"
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{
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printf 'resolved_active=%s\n' "$(systemctl is-active systemd-resolved 2>/dev/null || true)"
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printf 'resolved_enabled=%s\n' "$(systemctl is-enabled systemd-resolved 2>/dev/null || true)"
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} > "$path/metadata"
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printf '%s\n' "$path" > "$CURRENT_FILE"
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info "Backup: $path"
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# Roll back this transaction automatically if a command or signal fails.
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trap 'rc=$?; trap - ERR INT TERM; failed "Apply failed (exit $rc). Rolling back"; rollback_to "$path" || failed "Automatic rollback failed; backup: $path"; exit "$rc"' ERR
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trap 'exit 130' INT
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trap 'exit 143' TERM
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if ! grep -Eq '^[[:space:]]*hosts:[[:space:]]*files[[:space:]]+myhostname[[:space:]]+dns[[:space:]]*$' "$NSS"; then
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sed -i -E '/^[[:space:]]*hosts:/c\hosts: files myhostname dns' "$NSS"
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else skipped 'NSS already configured'; fi
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if [[ ! -f "$RESOLV" || -L "$RESOLV" ]] || ! grep -Eq '^nameserver[[:space:]]+127\.0\.0\.1$' "$RESOLV"; then
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local search_domain=""
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search_domain=$(awk '$1=="search" { $1=""; sub(/^[[:space:]]+/, ""); print; exit }' "$RESOLV" 2>/dev/null || true)
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rm -f "$RESOLV"
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{
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printf '# Local BIND9 recursive resolver; DNSSEC validated by BIND9.\n'
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printf 'nameserver 127.0.0.1\noptions edns0 trust-ad\n'
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[[ -z "$search_domain" ]] || printf 'search %s\n' "$search_domain"
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} > "$RESOLV"
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chmod 644 "$RESOLV"
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else skipped 'resolv.conf already uses local BIND9'; fi
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echononl 'NSS forward resolution'
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getent ahostsv4 oopen.de >/dev/null && ok 'works' || { echo; false; }
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echononl 'NSS reverse resolution'
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getent hosts 2607:f8b0:4864:20::72e >/dev/null && ok 'works' || { echo; false; }
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echononl 'Resolver configuration'
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is_direct && ok 'direct BIND9' || { echo; false; }
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systemctl stop systemd-resolved
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systemctl disable systemd-resolved >/dev/null
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echononl 'systemd-resolved disabled'
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is_fully_switched && ok 'yes' || { echo; false; }
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preflight
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sync_postfix
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trap - ERR INT TERM
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ok 'Switch completed successfully'
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info "Rollback available: $0 --rollback"
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}
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repair_postfix(){
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require_root
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need systemctl; need postconf; need cmp
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if ! is_direct; then
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fatal 'Resolver is not configured for direct BIND9; use --check first'
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fi
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if ! preflight; then
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fatal 'Local DNSSEC preflight failed; Postfix unchanged'
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fi
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sync_postfix
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ok 'Postfix DNS synchronization completed'
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}
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rollback(){
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require_root
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local path
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path=$(state_dir_from_marker) || fatal 'No rollback state from this script exists'
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info "Rollback backup: $path"
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confirm || { skipped 'Abbruch durch User'; exit 0; }
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rollback_to "$path"
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rm -f "$CURRENT_FILE"
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ok 'Rollback completed; preserved backup remains in place'
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}
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case "$MODE" in
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--help)
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cat <<'HELP'
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Usage: switch-resolver-to-bind9.sh [--check|--apply|--rollback|--repair-postfix|--help]
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--check read-only checks (default)
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--apply verify BIND9 DNSSEC; back up; switch DNS/NSS; stop+disable resolved
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--rollback restore files and resolved service state saved before last --apply
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--repair-postfix restart active Postfix instance(s) to refresh chroot DNS
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--help this help
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After Postfix restart: consider postqueue -f to retry deferred messages.
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Notes: run as root; requires BIND9 already working; no package changes.
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HELP
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;;
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--check) show_check ;;
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--apply) apply ;;
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--rollback) rollback ;;
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--repair-postfix) repair_postfix ;;
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esac
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