proxmox: add IPA sudo and local backdoor scripts, update bootstrap notes

- setup-ipa-sudo.sh: grants %admins group NOPASSWD sudo after ipa-client-install;
  writes admins-proxmox (pvesh/qm/pct) only when those binaries are present,
  so the same script works on PBS/PDM as well as PVE hosts
- create-local-backdoor.sh: creates a local 'pveadmin' account with SSH key
  and NOPASSWD sudo as an emergency fallback when IPA/SSSD is unavailable;
  password set via BACKDOOR_PASS env var or prompted interactively
- bootstrap.sh: appended post-IPA-enrollment reminder to the final checklist

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

proxmox/scripts/bootstrap.sh

@@ -65,3 +65,9 @@ fi
 echo "  - ${SCRIPT_DIR}/create-admin-user.sh <username>   (PVE web UI account)"
 echo "  - Enable 2FA/TOTP for that user and root@pam via the web UI"
 echo "  - ${SCRIPT_DIR}/audit.sh   (verify everything above)"
+echo
+echo "  If this host will be enrolled in FreeIPA:"
+echo "    ipa-client-install --domain=sweet.home --realm=SWEET.HOME \\"
+echo "      --server=domain-controller.sweet.home --mkhomedir --ssh-trust-dns --no-ntp"
+echo "    ${SCRIPT_DIR}/setup-ipa-sudo.sh         (NOPASSWD sudo for IPA admins group)"
+echo "    ${SCRIPT_DIR}/create-local-backdoor.sh <ssh-pubkey>  (emergency local account)"

proxmox/scripts/create-local-backdoor.sh

@@ -0,0 +1,84 @@
+#!/bin/bash
+# Create a local 'pveadmin' account as an emergency backdoor for when
+# IPA/SSSD is unavailable. The account authenticates by SSH key only
+# (password auth is disabled by harden-ssh.sh); the password set here
+# is for physical console access only.
+#
+# Idempotent - safe to re-run. If the account already exists, the SSH key
+# is refreshed but the password and account are left unchanged. Run as root.
+#
+# Usage:
+#   ./create-local-backdoor.sh <ssh-public-key>
+#   ./create-local-backdoor.sh --key-file <path-to-.pub>
+#
+# Set BACKDOOR_PASS env var to supply the console password non-interactively;
+# otherwise you will be prompted.
+set -euo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+# shellcheck source=lib/common.sh
+source "${SCRIPT_DIR}/lib/common.sh"
+require_root
+
+USERNAME="pveadmin"
+
+SSH_KEY=""
+if [ "${1:-}" = "--key-file" ]; then
+    KEY_FILE="${2:-}"
+    [ -z "$KEY_FILE" ] && { echo "ERROR: --key-file requires a path." >&2; exit 1; }
+    [ -f "$KEY_FILE" ] || { echo "ERROR: key file not found: $KEY_FILE" >&2; exit 1; }
+    SSH_KEY="$(cat "$KEY_FILE")"
+else
+    SSH_KEY="${1:-}"
+fi
+
+if [ -z "$SSH_KEY" ]; then
+    echo "Usage: $0 <ssh-public-key>" >&2
+    echo "       $0 --key-file <path-to-.pub>" >&2
+    exit 1
+fi
+
+if ! echo "$SSH_KEY" | grep -qE '^(ssh-rsa|ssh-ed25519|ecdsa-sha2-nistp[0-9]+) [A-Za-z0-9+/=]'; then
+    echo "ERROR: argument doesn't look like a valid SSH public key." >&2
+    exit 1
+fi
+
+if id "$USERNAME" >/dev/null 2>&1; then
+    echo "User '${USERNAME}' already exists -- not modifying account or password."
+else
+    useradd --create-home --shell /bin/bash "$USERNAME"
+    echo "Created Linux user '${USERNAME}'."
+
+    if [ -n "${BACKDOOR_PASS:-}" ]; then
+        printf '%s:%s\n' "$USERNAME" "$BACKDOOR_PASS" | chpasswd
+        echo "Console password set."
+    else
+        echo "Set a console password for '${USERNAME}' (used for physical console access only):"
+        passwd "$USERNAME"
+    fi
+fi
+
+HOME_DIR="$(getent passwd "$USERNAME" | cut -d: -f6)"
+SSH_DIR="${HOME_DIR}/.ssh"
+AUTH_FILE="${SSH_DIR}/authorized_keys"
+
+mkdir -p "$SSH_DIR"
+chmod 700 "$SSH_DIR"
+chown "${USERNAME}:${USERNAME}" "$SSH_DIR"
+
+if grep -qF "$SSH_KEY" "$AUTH_FILE" 2>/dev/null; then
+    echo "SSH key already present in ${AUTH_FILE}."
+else
+    printf '%s\n' "$SSH_KEY" >> "$AUTH_FILE"
+    echo "Installed SSH key in ${AUTH_FILE}."
+fi
+chmod 600 "$AUTH_FILE"
+chown "${USERNAME}:${USERNAME}" "$AUTH_FILE"
+
+SUDOERS_FILE="/etc/sudoers.d/${USERNAME}-nopasswd"
+write_if_changed "$SUDOERS_FILE" "${USERNAME} ALL=(root) NOPASSWD: ALL"
+chmod 0440 "$SUDOERS_FILE"
+visudo -c >/dev/null
+echo "Sudoers rule for '${USERNAME}' is valid."
+echo
+echo "'${USERNAME}' is ready: SSH key login, NOPASSWD sudo, console password set."

proxmox/scripts/setup-ipa-sudo.sh

@@ -0,0 +1,45 @@
+#!/bin/bash
+# Grant the IPA 'admins' group passwordless sudo on this host.
+#
+# Writes two files:
+#   /etc/sudoers.d/admins-nopasswd  -- NOPASSWD: ALL for general shell use
+#   /etc/sudoers.d/admins-proxmox   -- NOPASSWD for pvesh/qm/pct (PVE only;
+#                                      skipped silently if those binaries
+#                                      aren't present, e.g. on PBS/PDM)
+#
+# Idempotent - safe to re-run. Run as root on the target host after
+# ipa-client-install has been completed and SSSD is active.
+#
+# Usage: ./setup-ipa-sudo.sh
+set -euo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+# shellcheck source=lib/common.sh
+source "${SCRIPT_DIR}/lib/common.sh"
+require_root
+
+if [ ! -f /etc/ipa/default.conf ]; then
+    echo "ERROR: /etc/ipa/default.conf not found -- is this host enrolled in FreeIPA?" >&2
+    exit 1
+fi
+
+write_if_changed /etc/sudoers.d/admins-nopasswd '%admins ALL=(root) NOPASSWD: ALL'
+chmod 0440 /etc/sudoers.d/admins-nopasswd
+
+# PVE-specific tools -- pvesh moved from /usr/sbin to /usr/bin in PVE 8.x;
+# resolve at script time so the path in the sudoers rule is always correct.
+PVESH="$(command -v pvesh 2>/dev/null || true)"
+QM="$(command -v qm 2>/dev/null || true)"
+PCT="$(command -v pct 2>/dev/null || true)"
+
+if [ -n "$PVESH" ] && [ -n "$QM" ] && [ -n "$PCT" ]; then
+    write_if_changed /etc/sudoers.d/admins-proxmox \
+        "%admins ALL=(root) NOPASSWD: ${PVESH}, ${QM}, ${PCT}"
+    chmod 0440 /etc/sudoers.d/admins-proxmox
+    echo "Proxmox tools found -- wrote admins-proxmox."
+else
+    echo "pvesh/qm/pct not found -- skipping admins-proxmox (not a PVE host)."
+fi
+
+visudo -c >/dev/null
+echo "All sudoers files valid. IPA admins group has sudo on this host."