original nftables configuration

nftables.conf (text/plain), 3.50 KB, created by onkobu on 2021-10-22 10:36:02 UTC

flush ruleset

# inet family allows ip and ip6 rules
table inet firewall {

    chain inbound_ipv4 {
        # accepting ping (icmp-echo-request) for diagnostic purposes.
        # However, it also lets probes discover this host is alive.
        # This sample accepts them within a certain rate limit:
        #
        icmp type echo-request limit rate 5/second accept
    }

    chain inbound_ipv6 {
        # accept neighbour discovery otherwise connectivity breaks
        #
        icmpv6 type { nd-neighbor-solicit, nd-router-advert, nd-neighbor-advert } accept

        # accepting ping (icmpv6-echo-request) for diagnostic purposes.
        # However, it also lets probes discover this host is alive.
        # This sample accepts them within a certain rate limit:
        #
        icmpv6 type echo-request limit rate 5/second accept
    }

    chain inbound {

        # By default, drop all traffic unless it meets a filter
        # criteria specified by the rules that follow below.
        type filter hook input priority 0; policy drop;

        # Allow traffic from established and related packets, drop invalid
        ct state vmap { established : accept, related : accept, invalid : drop }

	    tcp flags & (fin|syn|rst|ack) != syn ct state new counter drop
		
        # Allow loopback traffic.
        iifname lo accept

        # Jump to chain according to layer 3 protocol using a verdict map
        meta protocol vmap { ip : jump inbound_ipv4, ip6 : jump inbound_ipv6 }

        # Allow SSH on port TCP/22 and allow HTTP(S) TCP/80 and TCP/443
        # for IPv4 and IPv6.
		# 8000 mpd
		# 8200 minidlna
		# 8883 mosquitto
        tcp dport { 22, 80, 443, 8000, 8200, 8883} accept

		meta l4proto { tcp, udp } th dport 53 counter packets 0 bytes 0 accept comment "accept DNS"

		# UPnP/ multicast
		udp dport 1900 meta pkttype multicast limit rate 4/second burst 20 packets accept comment "Accept UPnP IGD port mapping reply"

		# IGMP, could also jump to a chain that silently drops
		meta l4proto 2 ip daddr 224.0.0.0/24 accept comment "accept IGMP"
		meta l4proto 2 ip daddr 239.255.255.250 accept comment "accept IGMP digital radio"

        # Uncomment to enable logging of denied inbound traffic
        log prefix "[nftables] Inbound Denied: " counter drop
    }

    chain forward {
        # Drop everything (assumes this device is not a router)
        type filter hook forward priority 0; policy drop;
    }

    # no need to define output chain, default policy is accept if undefined.
}

# Separate table for hook ingress to filter bad packets early.
table netdev filter {
  # List of ipv4 addresses to block.
  set blocklist_v4 {
    # The "ipv4_addr" are for ipv4 addresses and "flags interval" allows to set intervals.
    type ipv4_addr; flags interval;
    elements = {
	  169.254.0.0/16,
	  172.16.0.0/12,192.0.2.0/24,
	  10.0.0.0/8
    }
	# suppress conflicting ip ranges,
	# e.g. 224.0.0.0/3,240.0.0.0/5 -> 224.0.0.0-255.255.255.255
	#auto-merge
  }

  chain ingress {
    # For some reason the interface must be hardcoded here, variable do not work.
    type filter hook ingress device enp8s0 priority -500;

    # Drop all fragments.
    ip frag-off & 0x1fff != 0 counter drop

    # Drop bad addresses.
    #ip saddr @blocklist_v4 counter drop

    # Drop XMAS packets.
    tcp flags & (fin|syn|rst|psh|ack|urg) == fin|syn|rst|psh|ack|urg counter drop

    # Drop NULL packets.
    tcp flags & (fin|syn|rst|psh|ack|urg) == 0x0 counter drop

    # Drop uncommon MSS values.
    tcp flags syn tcp option maxseg size 1-535 counter drop
  }
}