$ vim firewall.tf
resource "google_compute_firewall" "allow-icmp-ssh-ipv4" {
  name    = "allow-icmp-ssh-ipv4"
  network = google_compute_network.vpc_network_dual.self_link

  allow {
    protocol = "icmp"
  }

  allow {
    protocol = "tcp"
    ports    = ["22"]
  }

  source_ranges = ["0.0.0.0/0"]
}

resource "google_compute_firewall" "allow-ssh-icmp-ipv6" {
  name    = "allow-ssh-icmp-ipv6"
  network = google_compute_network.vpc_network_dual.self_link

  allow {
    protocol = "tcp"
    ports    = ["22"]
  }

  allow {
    protocol = "58" /* ipv6-icmp */
  }

  source_ranges = ["::/0"]
}