Revert package/ restructure, restore scripts to repo root

Moves all automated scripts back to the repo root where setup.sh
expects them. standalone/ remains for manual-run tools.

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

.gitignore

@@ -1,3 +1,4 @@
 config.sh
 whitelist.conf
 logs/
+*.log

README-scanner.md

@@ -5,7 +5,7 @@ Quick scanner for CVE-2025-66478 / CVE-2025-55182 (CVSS 10.0)
 ## Usage
 
 ```bash
-curl -o check-nextjs-rce.sh http://100.120.125.113:3000/pdm/security-tools/raw/branch/main/check-nextjs-rce.sh
+curl -o check-nextjs-rce.sh http://100.120.125.113:3000/pdm/security-tools/raw/branch/master/check-nextjs-rce.sh
   chmod +x check-nextjs-rce.sh
   sudo ./check-nextjs-rce.sh
 ```

README.md

@@ -2,6 +2,71 @@
 
 A collection of security scripts versioned in this repository.
 
+## Scripts
+
+### check-npm-sudo-config.sh
+
+Audits npm configuration on a Linux VM to detect cases where npm is — or has
+been — configured to install packages into system-owned directories, which
+requires `sudo` and creates security risks.
+
+Running `sudo npm install -g` can deposit files owned by root inside your npm
+prefix or cache directory. This causes permission errors for non-root users,
+encourages further `sudo npm` use to work around them, and means malicious
+packages run with root privileges during installation.
+
+**This script is audit-only — it makes no changes.** It reports issues and
+prints recommended commands, but you must run those commands yourself.
+
+The script checks:
+
+1. **npm prefix** — flags if it points to `/usr` or `/usr/local` (system-wide, requires sudo)
+2. **~/.npmrc** — checks whether the prefix is explicitly pinned to a user directory
+3. **PATH** — confirms the npm prefix bin directory is in PATH
+4. **Root-owned files in the prefix** — evidence of past `sudo npm` usage
+5. **Shell history** — scans `.bash_history` / `.zsh_history` for `sudo npm` commands
+6. **npm cache ownership** — root-owned cache files cause EACCES errors
+7. **Node version manager** — detects nvm, fnm, or n; flags if n is present without N_PREFIX set
+
+If issues are found, it sends a Telegram alert and logs results to `logs/`.
+
+The correct fix is to configure npm to install global packages into a
+user-owned directory (e.g. `~/.npm-global`) so that `sudo` is never needed:
+
+```bash
+npm config set prefix ~/.npm-global
+export PATH="$HOME/.npm-global/bin:$PATH"
+```
+
+## Standalone Scripts
+
+These scripts live in `standalone/` and are **not run by `setup.sh`**. They are
+single-use tools intended to be copied to a target machine and run manually.
+
+### standalone/bind-ssh-tailscale.sh
+
+Binds SSH to the Tailscale interface only and disables password authentication.
+
+- Requires root (`sudo bash bind-ssh-tailscale.sh`)
+- Tailscale must be installed and connected before running
+- Uses a drop-in config at `/etc/ssh/sshd_config.d/99-tailscale-only.conf` if
+  that directory exists; otherwise edits `/etc/ssh/sshd_config` directly with
+  an automatic backup
+- Validates the config with `sshd -t` before restarting the SSH service
+- Prints revert instructions on completion
+
+**To use on a target machine:**
+
+```bash
+curl -O https://gitea.pdmarf.co.uk/pdm/security-tools/raw/branch/master/standalone/bind-ssh-tailscale.sh
+# or via Tailscale:
+curl -O http://100.120.125.113:3000/pdm/security-tools/raw/branch/master/standalone/bind-ssh-tailscale.sh
+
+sudo bash bind-ssh-tailscale.sh
+```
+
+---
+
 ## Claude Code Context
 
 This project is maintained with Claude Code. The working directory on macOS is:
@@ -55,33 +120,6 @@ After cloning, run `setup.sh` once. It will:
 - Send a test Telegram message confirming the VM is active
 - Create a `logs/` folder — logs are kept for 60 days then auto-deleted
 
-## Whitelisting Known-Safe Findings
-
-If a script flags something you know is safe, add it to `whitelist.conf` on that VM to suppress it in future scans. This file is VM-specific and never committed to git.
-
-Add a package name:
-```bash
-echo "ua-parser-js" >> ~/security-tools/whitelist.conf
-```
-
-Add a file path:
-```bash
-echo "/tmp/my-known-script.sh" >> ~/security-tools/whitelist.conf
-```
-
-View or edit the whitelist:
-```bash
-nano ~/security-tools/whitelist.conf
-```
-
-## Checking Script Versions
-
-To see which version of a script is running on a VM:
-```bash
-head -2 ~/security-tools/npm-security-check.sh
-head -2 ~/security-tools/check-nextjs-rce.sh
-```
-
 ## Updating an Existing VM
 
 When changes are pushed to this repo, update any VM by running:

check-nextjs-rce.sh

@@ -1,5 +1,4 @@
 #!/bin/bash
-# check-nextjs-rce.sh v1.0
 # Next.js CVE-2025-66478 / CVE-2025-55182 Vulnerability Checker
 # Checks if Next.js installations are vulnerable to critical RCE
 

check-npm-sudo-config.sh

@@ -0,0 +1,200 @@
+#!/usr/bin/env bash
+# check-npm-sudo-config.sh v1.0
+# Audits npm configuration on this VM for sudo-related issues and recommends fixes.
+
+set -euo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+# shellcheck source=config.sh
+source "$SCRIPT_DIR/config.sh"
+
+send_telegram() {
+    curl -s -X POST "https://api.telegram.org/bot${TELEGRAM_BOT_TOKEN}/sendMessage" \
+        -d chat_id="${TELEGRAM_CHAT_ID}" \
+        -d text="$1" \
+        -d parse_mode="HTML" > /dev/null || true
+}
+
+HOSTNAME=$(hostname)
+DATE=$(date)
+LOGFILE="$SCRIPT_DIR/logs/npm-sudo-config-$(date +%Y%m%d).log"
+mkdir -p "$SCRIPT_DIR/logs"
+
+RED='\033[0;31m'
+YELLOW='\033[1;33m'
+GREEN='\033[0;32m'
+BOLD='\033[1m'
+RESET='\033[0m'
+
+ISSUES=0
+WARNINGS=0
+
+log()    { echo "$*" | tee -a "$LOGFILE"; }
+ok()     { log "$(printf "${GREEN}✓${RESET} %s" "$*")"; }
+warn()   { log "$(printf "${YELLOW}⚠${RESET} %s" "$*")"; (( WARNINGS++ )) || true; }
+fail()   { log "$(printf "${RED}✗${RESET} %s" "$*")"; (( ISSUES++ )) || true; }
+rec()    { log "$(printf "  ${YELLOW}→${RESET} %s" "$*")"; }
+header() { log ""; log "=========================================="; log "$*"; log "=========================================="; }
+
+log "=========================================="
+log "  npm sudo config audit"
+log "=========================================="
+log "Hostname : $HOSTNAME"
+log "Date     : $DATE"
+
+# ── 1. npm present? ───────────────────────────────────────────────────────────
+header "1. npm availability"
+
+if ! command -v npm &>/dev/null; then
+    warn "npm not found in PATH — skipping remaining checks"
+    echo ""
+    echo "RESULT: 0 issue(s), 1 warning(s)"
+    exit 0
+fi
+
+NPM_PATH=$(command -v npm)
+ok "npm found: $NPM_PATH"
+
+# ── 2. npm prefix ─────────────────────────────────────────────────────────────
+header "2. npm prefix"
+
+PREFIX=$(npm config get prefix 2>/dev/null || echo "unknown")
+log "Current prefix: $PREFIX"
+
+if [[ "$PREFIX" == "/usr" || "$PREFIX" == "/usr/local" ]]; then
+    fail "npm prefix is $PREFIX (system-wide) — global installs require sudo"
+    rec "npm config set prefix ~/.npm-global"
+    rec "Add to ~/.profile: export PATH=\"\$HOME/.npm-global/bin:\$PATH\""
+elif [[ "$PREFIX" == "unknown" ]]; then
+    warn "Could not determine npm prefix"
+else
+    PREFIX_OWNER=$(stat -c "%U" "$PREFIX" 2>/dev/null || echo "unknown")
+    if [[ "$PREFIX_OWNER" == "root" ]]; then
+        fail "npm prefix $PREFIX is owned by root — global installs require sudo"
+        rec "sudo chown -R \$(whoami) $PREFIX"
+        rec "Or set a user-owned prefix: npm config set prefix ~/.npm-global"
+    else
+        ok "npm prefix is $PREFIX (owned by $PREFIX_OWNER)"
+    fi
+fi
+
+# ── 3. .npmrc ────────────────────────────────────────────────────────────────
+header "3. ~/.npmrc"
+
+if [[ -f "$HOME/.npmrc" ]]; then
+    log "$(cat "$HOME/.npmrc")"
+    NPM_PREFIX_LINE=$(grep "^prefix=" "$HOME/.npmrc" 2>/dev/null || true)
+    if [[ -n "$NPM_PREFIX_LINE" ]]; then
+        ok ".npmrc explicitly sets: $NPM_PREFIX_LINE"
+    else
+        warn ".npmrc exists but does not pin the prefix"
+        rec "npm config set prefix ~/.npm-global"
+    fi
+else
+    warn "No ~/.npmrc — prefix is not pinned to a user directory"
+    rec "npm config set prefix ~/.npm-global"
+fi
+
+# ── 4. prefix/bin in PATH ─────────────────────────────────────────────────────
+header "4. npm prefix bin in PATH"
+
+if [[ "$PREFIX" != "unknown" ]]; then
+    PREFIX_BIN="${PREFIX}/bin"
+    if echo "$PATH" | tr ':' '\n' | grep -qxF "$PREFIX_BIN"; then
+        ok "$PREFIX_BIN is in PATH"
+    else
+        warn "$PREFIX_BIN is NOT in PATH — globally installed binaries won't run"
+        PROFILE_FILE="$HOME/.profile"
+        [[ -f "$HOME/.zshrc" ]] && PROFILE_FILE="$HOME/.zshrc"
+        rec "Add to $PROFILE_FILE: export PATH=\"$PREFIX_BIN:\$PATH\""
+        rec "Then reload: source $PROFILE_FILE"
+    fi
+fi
+
+# ── 5. Root-owned files in npm prefix ────────────────────────────────────────
+header "5. Root-owned files in npm prefix"
+
+if [[ -d "$PREFIX" ]]; then
+    ROOT_FILES=$(find "$PREFIX" -maxdepth 3 -user root 2>/dev/null | head -5 || true)
+    if [[ -n "$ROOT_FILES" ]]; then
+        fail "Root-owned files found in npm prefix (past sudo npm usage):"
+        echo "$ROOT_FILES"
+        rec "sudo chown -R \$(whoami) $PREFIX"
+    else
+        ok "No root-owned files in $PREFIX"
+    fi
+else
+    ok "npm prefix directory does not exist yet (no global installs made)"
+fi
+
+# ── 6. sudo npm in shell history ─────────────────────────────────────────────
+header "6. Shell history — sudo npm usage"
+
+SUDO_NPM_FOUND=false
+for hfile in "$HOME/.bash_history" "$HOME/.zsh_history"; do
+    if [[ -f "$hfile" ]]; then
+        HITS=$(grep -c "sudo npm" "$hfile" 2>/dev/null || true)
+        if [[ "$HITS" -gt 0 ]]; then
+            warn "Found $HITS occurrence(s) of \"sudo npm\" in $hfile"
+            SUDO_NPM_FOUND=true
+        fi
+    fi
+done
+$SUDO_NPM_FOUND || ok "No \"sudo npm\" in shell history"
+
+# ── 7. npm cache ownership ───────────────────────────────────────────────────
+header "7. npm cache ownership"
+
+CACHE_DIR=$(npm config get cache 2>/dev/null || echo "$HOME/.npm")
+if [[ -d "$CACHE_DIR" ]]; then
+    ROOT_CACHE=$(find "$CACHE_DIR" -maxdepth 2 -user root 2>/dev/null | head -3 || true)
+    if [[ -n "$ROOT_CACHE" ]]; then
+        fail "Root-owned files in npm cache ($CACHE_DIR) — will cause EACCES errors"
+        rec "sudo chown -R \$(whoami) $CACHE_DIR"
+    else
+        ok "npm cache ($CACHE_DIR) is user-owned"
+    fi
+else
+    ok "npm cache directory does not exist yet"
+fi
+
+# ── 8. Node version manager ───────────────────────────────────────────────────
+header "8. Node version manager"
+
+if command -v n &>/dev/null; then
+    N_PREFIX_VAL="${N_PREFIX:-}"
+    if [[ -z "$N_PREFIX_VAL" ]]; then
+        warn "n is installed but N_PREFIX is not set — n defaults to /usr/local (requires sudo)"
+        rec "Add to ~/.profile: export N_PREFIX=\$HOME/.n"
+        rec "Add to ~/.profile: export PATH=\$PATH:\$N_PREFIX/bin"
+    else
+        ok "n is installed, N_PREFIX=$N_PREFIX_VAL"
+    fi
+elif [[ -s "$HOME/.nvm/nvm.sh" ]] || command -v nvm &>/dev/null 2>&1; then
+    ok "nvm is managing Node (sudo-free by design)"
+elif command -v fnm &>/dev/null; then
+    ok "fnm is managing Node (sudo-free by design)"
+else
+    ok "No Node version manager detected"
+fi
+
+# ── Summary ───────────────────────────────────────────────────────────────────
+header "SUMMARY"
+log "Scan completed at: $(date)"
+log "Log saved to     : $LOGFILE"
+log ""
+
+if [[ $ISSUES -gt 0 ]]; then
+    printf "${RED}✗ %d issue(s) and %d warning(s) — see recommendations above${RESET}\n" "$ISSUES" "$WARNINGS"
+    send_telegram "⚠️ <b>npm sudo config issues</b>
+Host: <code>${HOSTNAME}</code>
+Issues: ${ISSUES} | Warnings: ${WARNINGS}
+Run manually: bash check-npm-sudo-config.sh"
+    exit 1
+elif [[ $WARNINGS -gt 0 ]]; then
+    printf "${YELLOW}⚠ Clean but %d warning(s) — see recommendations above${RESET}\n" "$WARNINGS"
+    exit 0
+else
+    printf "${GREEN}✓ npm is correctly configured on %s${RESET}\n" "$HOSTNAME"
+    exit 0
+fi

npm-security-check.sh

@@ -1,5 +1,5 @@
 #!/usr/bin/env bash
-# npm-security-check.sh v1.0
+# npm-security-check.sh
 # Scans for NPM/Node.js malware indicators on this VM.
 
 set -euo pipefail
@@ -18,11 +18,6 @@ send_telegram() {
 HOSTNAME=$(hostname)
 DATE=$(date)
 LOGFILE="${1:-npm_security_check_${HOSTNAME}_$(date +%Y%m%d_%H%M%S).log}"
-WHITELIST="$SCRIPT_DIR/whitelist.conf"
-
-is_whitelisted() {
-    [[ -f "$WHITELIST" ]] && grep -qF "$1" "$WHITELIST" 2>/dev/null
-}
 
 RED='\033[0;31m'
 YELLOW='\033[1;33m'
@@ -90,10 +85,6 @@ else
     COUNT=$(echo "$LOCKFILES" | wc -l)
     log "Scanning $COUNT lock file(s)..."
     for pkg in "${BAD_PKGS[@]}"; do
-        if is_whitelisted "$pkg"; then
-            ok "$pkg is whitelisted — skipping"
-            continue
-        fi
         MATCHES=$(echo "$LOCKFILES" | xargs grep -l "\"$pkg\"" 2>/dev/null || true)
         if [[ -n "$MATCHES" ]]; then
             fail "Found '$pkg' in: $MATCHES"
@@ -215,14 +206,12 @@ for dir in /tmp /dev/shm /var/tmp; do
     EXEC_FILES=$(find "$dir" -type f -executable 2>/dev/null | head -20 || true)
     JS_FILES=$(find "$dir" -name "*.js" -o -name "*.mjs" 2>/dev/null | head -10 || true)
     if [[ -n "$EXEC_FILES" ]]; then
-        while IFS= read -r f; do
-            is_whitelisted "$f" && ok "$f is whitelisted — skipping" || { warn "Executable file in $dir: $f"; }
-        done <<< "$EXEC_FILES"
+        warn "Executable files in $dir:"
+        log "$EXEC_FILES"
     fi
     if [[ -n "$JS_FILES" ]]; then
-        while IFS= read -r f; do
-            is_whitelisted "$f" && ok "$f is whitelisted — skipping" || { warn "JS file in $dir: $f"; }
-        done <<< "$JS_FILES"
+        warn "JS files in $dir:"
+        log "$JS_FILES"
     fi
 done
 ok "Temp directory scan complete"

setup.sh

@@ -1,5 +1,5 @@
 #!/usr/bin/env bash
-# setup.sh v1.1
+# setup.sh
 # Run once after cloning on any VM where you want security scanning active.
 
 set -euo pipefail
@@ -9,6 +9,10 @@ SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
 echo "=== Security Tools Setup ==="
 echo ""
 
+# ── Git config ────────────────────────────────────────────────────────────────
+git -C "$SCRIPT_DIR" config pull.rebase false
+echo "Git pull strategy set to merge."
+
 # ── Telegram credentials ───────────────────────────────────────────────────────
 if [[ -f "$SCRIPT_DIR/config.sh" ]]; then
     echo "config.sh already exists — skipping credential setup."
@@ -31,33 +35,16 @@ fi
 # ── Make scripts executable ────────────────────────────────────────────────────
 chmod +x "$SCRIPT_DIR/npm-security-check.sh"
 chmod +x "$SCRIPT_DIR/check-nextjs-rce.sh"
+chmod +x "$SCRIPT_DIR/check-npm-sudo-config.sh"
 
 # ── Create logs directory ──────────────────────────────────────────────────────
 mkdir -p "$SCRIPT_DIR/logs"
 
-# ── Create whitelist if absent ─────────────────────────────────────────────────
-if [[ ! -f "$SCRIPT_DIR/whitelist.conf" ]]; then
-    cat > "$SCRIPT_DIR/whitelist.conf" <<'EOF'
-# whitelist.conf — one entry per line, exact match against package names or file paths
-# Example:
-#   ua-parser-js
-#   /tmp/my-known-safe-script.sh
-EOF
-    echo "whitelist.conf created — add known-safe items to suppress false positives."
-fi
-
-# ── Ensure cron is available ──────────────────────────────────────────────────
-if ! command -v crontab &>/dev/null; then
-    echo "cron not found — installing..."
-    apt install cron -y
-    systemctl enable cron
-    systemctl start cron
-fi
-
 # ── Cron jobs ──────────────────────────────────────────────────────────────────
 CRON_1="0 8 * * * $SCRIPT_DIR/npm-security-check.sh >> $SCRIPT_DIR/logs/npm-security-check-\$(date +\%Y\%m\%d).log 2>&1"
 CRON_2="5 8 * * * $SCRIPT_DIR/check-nextjs-rce.sh >> $SCRIPT_DIR/logs/check-nextjs-rce-\$(date +\%Y\%m\%d).log 2>&1"
-CRON_3="0 9 * * * find $SCRIPT_DIR/logs -name '*.log' -mtime +60 -delete"
+CRON_3="10 8 * * * $SCRIPT_DIR/check-npm-sudo-config.sh >> $SCRIPT_DIR/logs/check-npm-sudo-config-\$(date +\%Y\%m\%d).log 2>&1"
+CRON_4="0 9 * * * find $SCRIPT_DIR/logs -name '*.log' -mtime +60 -delete"
 
 EXISTING=$(crontab -l 2>/dev/null || true)
 
@@ -75,10 +62,17 @@ else
     echo "Cron job registered: check-nextjs-rce.sh daily at 08:05."
 fi
 
+if echo "$EXISTING" | grep -qF "check-npm-sudo-config.sh"; then
+    echo "Cron job for check-npm-sudo-config.sh already registered — skipping."
+else
+    (crontab -l 2>/dev/null; echo "$CRON_3") | crontab -
+    echo "Cron job registered: check-npm-sudo-config.sh daily at 08:10."
+fi
+
 if echo "$EXISTING" | grep -qF "logs -name '*.log'"; then
     echo "Log cleanup cron already registered — skipping."
 else
-    (crontab -l 2>/dev/null; echo "$CRON_3") | crontab -
+    (crontab -l 2>/dev/null; echo "$CRON_4") | crontab -
     echo "Cron job registered: log cleanup daily at 09:00 (60 day retention)."
 fi
 
@@ -109,5 +103,10 @@ echo ""
 echo "Running initial security scan..."
 bash "$SCRIPT_DIR/npm-security-check.sh" >> "$SCRIPT_DIR/logs/npm-security-check-$(date +%Y%m%d).log" 2>&1 && echo "npm-security-check: done." || echo "npm-security-check: issues found — check Telegram."
 bash "$SCRIPT_DIR/check-nextjs-rce.sh" >> "$SCRIPT_DIR/logs/check-nextjs-rce-$(date +%Y%m%d).log" 2>&1 && echo "check-nextjs-rce: done." || echo "check-nextjs-rce: issues found — check Telegram."
+NPM_SUDO_LOG="$SCRIPT_DIR/logs/check-npm-sudo-config-$(date +%Y%m%d).log"
+echo ""
+echo "--- npm sudo config audit results ---"
+bash "$SCRIPT_DIR/check-npm-sudo-config.sh" 2>&1 | tee -a "$NPM_SUDO_LOG"
+echo "-------------------------------------"
 echo ""
 echo "Initial scan complete. Check Telegram for any alerts."

standalone/bind-ssh-tailscale.sh

@@ -0,0 +1,75 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+log() { echo "[$(date +'%Y-%m-%d %H:%M:%S')] $1"; }
+
+if [ "$EUID" -ne 0 ]; then
+    log "ERROR: Please run as root"
+    exit 1
+fi
+
+# Check Tailscale is installed and connected
+if ! command -v tailscale &>/dev/null; then
+    log "ERROR: Tailscale is not installed"
+    exit 1
+fi
+
+TAILSCALE_IP=$(tailscale ip -4 2>/dev/null)
+if [ -z "$TAILSCALE_IP" ]; then
+    log "ERROR: Could not get Tailscale IP — is Tailscale connected?"
+    exit 1
+fi
+log "Tailscale IP: ${TAILSCALE_IP}"
+
+# Detect SSH service name
+if systemctl is-active --quiet ssh 2>/dev/null; then
+    SSH_SERVICE="ssh"
+elif systemctl is-active --quiet sshd 2>/dev/null; then
+    SSH_SERVICE="sshd"
+else
+    log "ERROR: No running SSH service found (tried ssh, sshd)"
+    exit 1
+fi
+
+# Use a drop-in file if sshd_config.d exists, otherwise edit sshd_config directly
+if [ -d /etc/ssh/sshd_config.d ]; then
+    DROPIN="/etc/ssh/sshd_config.d/99-tailscale-only.conf"
+    [ -f "$DROPIN" ] && log "WARNING: ${DROPIN} already exists — overwriting"
+    cat > "$DROPIN" << EOF
+# Bind SSH to Tailscale interface only
+# To revert: rm ${DROPIN} && systemctl restart ${SSH_SERVICE}
+ListenAddress ${TAILSCALE_IP}
+PasswordAuthentication no
+PermitEmptyPasswords no
+EOF
+    log "Written: ${DROPIN}"
+else
+    BACKUP="/etc/ssh/sshd_config.bak.$(date +%Y%m%d_%H%M%S)"
+    cp /etc/ssh/sshd_config "$BACKUP"
+    log "Backed up sshd_config to ${BACKUP}"
+
+    # Remove any existing ListenAddress lines and add ours
+    sed -i '/^[#]*ListenAddress/d' /etc/ssh/sshd_config
+    echo "ListenAddress ${TAILSCALE_IP}" >> /etc/ssh/sshd_config
+    log "Updated /etc/ssh/sshd_config"
+fi
+
+# Validate config before restarting
+if ! sshd -t; then
+    log "ERROR: SSH config validation failed — aborting without restart"
+    [ -n "${DROPIN:-}" ] && rm -f "$DROPIN"
+    exit 1
+fi
+log "SSH config validated OK"
+
+systemctl restart "$SSH_SERVICE"
+log "SSH service restarted"
+
+log ""
+log "Done. SSH is now bound to Tailscale only (${TAILSCALE_IP})"
+log "Connect with: ssh root@${TAILSCALE_IP}"
+if [ -d /etc/ssh/sshd_config.d ]; then
+    log "To revert:    rm ${DROPIN} && systemctl restart ${SSH_SERVICE}"
+else
+    log "To revert:    cp ${BACKUP} /etc/ssh/sshd_config && systemctl restart ${SSH_SERVICE}"
+fi