nftables-workstation.nft

   1 #!/usr/sbin/nft -f
   2 #
   3 # nftables ruleset for an End Node acting as a workstation in a LAN.
   4 #
   5 # Copyright (C) 2018  Antonio Ospite <ao2@ao2.it>
   6 # SPDX-License-Identifier: MIT
   7 #
   8 # Based on:
   9 # https://wiki.nftables.org/wiki-nftables/index.php/Quick_reference-nftables_in_10_minutes#Simple_IP.2FIPv6_Firewall
  10 # https://wiki.archlinux.org/index.php/Nftables#Workstation
  11 # https://stosb.com/blog/explaining-my-configs-nftables/
  12
  13 flush ruleset
  14
  15 table inet filter {
  16
  17     define common_open_ports = {
  18             xmpp-client,
  19             xmpp-server,
  20             5298, # Link-local XMPP, for backward compatibility, XEP-0174
  21     }
  22
  23     set tcp_open_ports {
  24         type inet_service
  25         flags interval
  26
  27         elements = {
  28             $common_open_ports,
  29         }
  30     }
  31
  32     set udp_open_ports {
  33         type inet_service
  34         flags interval
  35
  36         elements = {
  37             $common_open_ports,
  38         }
  39     }
  40
  41     chain input {
  42         type filter hook input priority 0;
  43
  44         ct state established,related accept
  45         ct state invalid drop
  46         ct state new jump in-new
  47
  48         iif lo accept
  49
  50         ip protocol icmp icmp type {
  51             echo-reply,
  52             echo-request,
  53             time-exceeded,
  54             parameter-problem,
  55             destination-unreachable
  56         } accept
  57
  58         # ICMPv6 configuration based on:
  59         # https://github.com/intel/intel-iot-refkit/blob/master/meta-refkit-core/recipes-security/nftables-settings-default/files/firewall.template
  60         ip6 nexthdr ipv6-icmp icmpv6 type {
  61             echo-reply,
  62             echo-request,
  63             time-exceeded,
  64             parameter-problem,
  65             destination-unreachable,
  66             packet-too-big
  67         } accept
  68
  69         # Allow auto configuration support.
  70         ip6 nexthdr ipv6-icmp icmpv6 type {
  71             nd-router-advert,
  72             nd-router-solicit,
  73             nd-neighbor-advert,
  74             nd-neighbor-solicit
  75         } ip6 hoplimit 255 accept
  76
  77         # Allow multicast listener discovery on link-local addresses.
  78         # RFC2710 specifies that a Hop-by-Hop Options header is used.
  79         hbh nexthdr ipv6-icmp icmpv6 type {
  80             mld-listener-query,
  81             mld-listener-report,
  82             mld-listener-reduction
  83         } ip6 saddr fe80::/10 accept
  84
  85         # Allow multicast router discovery messages on link-local addresses (hop limit 1).
  86         ip6 nexthdr ipv6-icmp icmpv6 type {
  87             nd-router-advert,
  88             nd-router-solicit
  89         } ip6 hoplimit 1 ip6 saddr fe80::/10 accept
  90
  91         # Allow IGMPv3 queries.
  92         ip protocol igmp ip daddr 224.0.0.1 accept
  93
  94         # Silently drop other incoming broadcast and multicast traffic.
  95         meta pkttype {broadcast, multicast} drop
  96
  97         limit rate 3/minute burst 10 packets log prefix "[INPUT]: "
  98         counter reject
  99     }
 100
 101     chain in-new {
 102         # Silently drop DHCPv4 Discover and Request packets from other clients.
 103         ip saddr 0.0.0.0 ip daddr 255.255.255.255 udp sport bootpc udp dport bootps drop
 104
 105         # Silently drop DHCPv6 from other clients.
 106         ip6 saddr fe80::/64 ip6 daddr fe80::/64 udp sport dhcpv6-client udp dport dhcpv6-server drop
 107
 108         # mDNS (ZeroConf/Bonjour)
 109         ip  daddr 224.0.0.251 udp dport mdns accept
 110         ip6 daddr ff02::fb    udp dport mdns accept
 111
 112         # SSDP: https://en.wikipedia.org/wiki/Simple_Service_Discovery_Protocol
 113         ip daddr 239.255.255.250 udp dport 1900 accept
 114         ip6 daddr {
 115             ff02::c,
 116             ff05::c,
 117             ff08::c,
 118             ff0e::c
 119         } udp dport 1900 accept
 120
 121         tcp dport @tcp_open_ports tcp flags & (fin | syn | rst | ack) == syn accept
 122         udp dport @udp_open_ports accept
 123     }
 124
 125     chain forward {
 126         type filter hook forward priority 0;
 127         limit rate 3/minute burst 10 packets log prefix "[FORWARD]: "
 128         counter reject
 129     }
 130
 131     chain output {
 132         type filter hook output priority 0;
 133         counter accept
 134     }
 135 }