build/layer/router-rpi3/nftables.rules

flush ruleset

table inet filter {
  chain input {
    type filter hook input priority 0; policy drop;

    ct state {established, related} accept
    ct state invalid drop

    iifname lo accept
    iifname wlan0 accept

    ip protocol icmp accept

    reject
  }

  chain forward {
    type filter hook forward priority 0;

    oifname port0 accept
    iifname port0 ct state related, established accept
    iifname port0 drop
  }

  chain output {
    type filter hook output priority 0; policy accept;
  }
}

table ip nat {
  chain prerouting {
    type nat hook prerouting priority 0;
  }

  chain postrouting {
    type nat hook postrouting priority 0;

    oifname port0 masquerade
  }
}