#!/usr/bin/env bash
# Locks the Swarm ports (2377 control, 7946 gossip, 4789 overlay VXLAN) to the
# WireGuard interface only — they must never be reachable from the public
# internet. Run on BOTH boxes after joining the swarm. Existing app-facing
# rules (80/443, SSH, etc.) are untouched.
set -euo pipefail

WG_IFACE="${WG_IFACE:-wg0}"

if ! command -v ufw >/dev/null 2>&1; then
  echo "ufw not found — apply the equivalent iptables/nftables rules by hand:" >&2
  echo "  allow 2377/tcp, 7946/tcp, 7946/udp, 4789/udp only on interface ${WG_IFACE}" >&2
  echo "  deny  2377/tcp, 7946/tcp, 7946/udp, 4789/udp on every other interface" >&2
  exit 1
fi

echo "==> Allowing Swarm ports on ${WG_IFACE} only"
ufw allow in on "$WG_IFACE" to any port 2377 proto tcp
ufw allow in on "$WG_IFACE" to any port 7946 proto tcp
ufw allow in on "$WG_IFACE" to any port 7946 proto udp
ufw allow in on "$WG_IFACE" to any port 4789 proto udp

echo "==> Explicitly denying the same ports on every other interface"
ufw deny 2377/tcp
ufw deny 7946/tcp
ufw deny 7946/udp
ufw deny 4789/udp

echo
echo "Rules added (not yet necessarily active — check ufw status):"
ufw status numbered | grep -E "2377|7946|4789|Status" || true
echo
echo "If ufw is inactive, enable it: ufw enable   (make sure your SSH port is"
echo "allowed FIRST, or you will lock yourself out)."