machines/losurdo/networking/nftables.nix

   1 { pkgs, lib, config, machines, ... }:
   2 let
   3   inherit (builtins) hasAttr readFile;
   4   inherit (pkgs.lib) unlinesAttrs;
   5   inherit (config.users) users groups;
   6 in
   7 {
   8 networking.firewall.enable = false;
   9 security.lockKernelModules = false;
  10 systemd.services.disable-kernel-module-loading.after = [ "nftables.service" ];
  11 systemd.services.nftables.serviceConfig.TimeoutStartSec = "20";
  12 networking.nftables = {
  13   enable = true;
  14   ruleset = lib.mkBefore ''
  15     table inet filter {
  16       set lograte {
  17         type ipv4_addr
  18         size 65535
  19         flags dynamic
  20       }
  21       chain ping-flood {
  22         add @lograte { ip saddr limit rate 1/minute } log level warn prefix "ping-flood: "
  23         counter drop
  24       }
  25       chain check-ping {
  26         ip protocol icmp   icmp   type echo-request limit rate over 10/second burst 20 packets goto ping-flood
  27         ip6 nexthdr icmpv6 icmpv6 type echo-request limit rate over 10/second burst 20 packets goto ping-flood
  28       }
  29       chain smurf {
  30         add @lograte { ip saddr limit rate 1/minute } log level warn prefix "smurf: "
  31         counter drop
  32       }
  33       chain check-broadcast {
  34         ip saddr 0.0.0.0/32 counter accept comment "DHCP broadcast"
  35         fib saddr type broadcast counter goto smurf
  36         ip saddr 224.0.0.0/4     counter goto smurf
  37       }
  38       chain bogus-tcp {
  39         add @lograte { ip saddr limit rate 1/minute } log level warn prefix "bogus-tcp: "
  40         counter drop
  41       }
  42       chain syn-flood {
  43         add @lograte { ip saddr limit rate 1/minute } log level warn prefix "syn-flood: "
  44         counter drop
  45       }
  46       chain check-tcp {
  47         tcp flags syn tcp option maxseg size != 536-65535 counter goto bogus-tcp
  48         tcp flags & (ack|fin) == fin counter goto bogus-tcp
  49         tcp flags & (ack|psh) == psh counter goto bogus-tcp
  50         tcp flags & (ack|urg) == urg counter goto bogus-tcp
  51         tcp flags & (fin|ack) == fin counter goto bogus-tcp
  52         tcp flags & (fin|rst) == (fin|rst) counter goto bogus-tcp
  53         tcp flags & (fin|psh|ack) == (fin|psh) counter goto bogus-tcp
  54         tcp flags & (syn|fin) == (syn|fin) counter goto bogus-tcp comment "SYN-FIN scan"
  55         tcp flags & (syn|rst) == (syn|rst) counter goto bogus-tcp comment "SYN-RST scan"
  56         tcp flags == (fin|syn|rst|psh|ack|urg) counter goto bogus-tcp comment "XMAS scan"
  57         tcp flags == 0x0 counter goto bogus-tcp comment "NULL scan"
  58         tcp flags == (fin|urg|psh) counter goto bogus-tcp
  59         tcp flags == (fin|urg|psh|syn) counter goto bogus-tcp comment "NMAP-ID"
  60         tcp flags == (fin|urg|syn|rst|ack) counter goto bogus-tcp
  61
  62         ct state new tcp flags != syn counter goto bogus-tcp
  63         tcp sport 0 tcp flags & (fin|syn|rst|ack) == syn counter goto bogus-tcp
  64         tcp flags & (fin|syn|rst|ack) == syn counter limit rate over 30/second burst 60 packets goto syn-flood
  65       }
  66       chain check-public {
  67         #ip saddr 224.0.0.0/3 counter drop
  68         #ip saddr 169.254.0.0/16 counter drop
  69         #ip saddr 172.16.0.0/12 counter drop
  70         #ip saddr 192.0.2.0/24 counter drop
  71         #ip saddr 192.168.0.0/16 counter drop
  72         #ip saddr 10.0.0.0/8 counter drop
  73         #ip saddr 0.0.0.0/8 counter drop
  74         #ip saddr 240.0.0.0/5 counter drop
  75         #ip saddr 127.0.0.0/8 counter drop
  76       }
  77       chain net2fw {
  78         #udp dport mdns ip6 daddr ff02::fb counter accept comment "Accept mDNS"
  79         #udp dport mdns ip daddr 224.0.0.251 counter accept comment "Accept mDNS"
  80         #jump non-internet
  81
  82         #ct state new add @connlimit { ip saddr ct count over 20 } counter tcp reject with tcp reset
  83
  84         # Some .nix append rules here with: add rule inet filter net2fw ...
  85       }
  86       chain fw2net {
  87         ip daddr 224.0.0.0/4 udp dport 1900 counter accept comment "UPnP"
  88         tcp dport { 80, 443 } counter accept comment "HTTP"
  89         udp dport 123 skuid ${users.systemd-timesync.name} counter accept comment "NTP"
  90         tcp dport 9418 counter accept comment "Git"
  91
  92         # Some .nix append rules here with: add rule inet filter fw2net ...
  93       }
  94       chain intra2fw {
  95         # Some .nix append rules here with: add rule inet filter intra2fw ...
  96       }
  97       chain fw2intra {
  98         # Some .nix append rules here with: add rule inet filter fw2intra ...
  99       }
 100       chain fwd-intra {
 101         # Some .nix append rules here with: add rule inet filter fwd-intra ...
 102       }
 103
 104       chain input {
 105         type filter hook input priority 0
 106         policy drop
 107
 108         iifname lo accept
 109
 110         jump check-tcp
 111         jump check-ping
 112         jump check-broadcast
 113
 114         ct state { established, related } accept
 115         ct state invalid counter drop
 116
 117         # admin services
 118         tcp dport 22 counter accept comment "SSH"
 119         udp dport 60000-61000 counter accept comment "Mosh"
 120
 121         # ICMP
 122         ip protocol icmp icmp type echo-request counter accept
 123         ip protocol icmp icmp type destination-unreachable counter accept
 124         ip protocol icmp icmp type router-solicitation counter accept
 125         ip protocol icmp icmp type router-advertisement counter accept
 126         ip protocol icmp icmp type time-exceeded counter accept
 127         ip protocol icmp icmp type parameter-problem counter accept
 128         #ip protocol icmp icmp type { echo-request, destination-unreachable, router-solicitation, router-advertisement, time-exceeded, parameter-problem } counter accept
 129         ip protocol icmp log level warn prefix "net2fw: icmpv: " counter accept
 130
 131         ip6 nexthdr icmpv6 icmpv6 type echo-request counter accept
 132         ip6 nexthdr icmpv6 icmpv6 type nd-neighbor-solicit counter accept
 133         ip6 nexthdr icmpv6 icmpv6 type nd-neighbor-advert counter accept
 134         ip6 nexthdr icmpv6 icmpv6 type nd-router-solicit counter accept
 135         ip6 nexthdr icmpv6 icmpv6 type nd-router-advert counter accept
 136         ip6 nexthdr icmpv6 icmpv6 type mld-listener-query counter accept
 137         ip6 nexthdr icmpv6 icmpv6 type mld-listener-report counter accept
 138         ip6 nexthdr icmpv6 icmpv6 type mld-listener-reduction counter accept
 139         ip6 nexthdr icmpv6 icmpv6 type destination-unreachable counter accept
 140         ip6 nexthdr icmpv6 icmpv6 type packet-too-big counter accept
 141         ip6 nexthdr icmpv6 icmpv6 type time-exceeded counter accept
 142         ip6 nexthdr icmpv6 icmpv6 type parameter-problem counter accept
 143         ip6 nexthdr icmpv6 icmpv6 type ind-neighbor-solicit counter accept
 144         ip6 nexthdr icmpv6 icmpv6 type ind-neighbor-advert counter accept
 145         ip6 nexthdr icmpv6 icmpv6 type mld2-listener-report counter accept
 146         ip6 nexthdr icmpv6 log level warn prefix "net2fw: icmpv6: " counter accept
 147         #ip6 nexthdr icmpv6 icmpv6 type { echo-request, nd-neighbor-solicit, nd-neighbor-advert, nd-router-solicit, nd-router-advert, mld-listener-query, mld-listener-report, mld-listener-reduction, destination-unreachable, packet-too-big, time-exceeded, parameter-problem, ind-neighbor-solicit, ind-neighbor-advert, mld2-listener-report } counter accept
 148
 149         # Some .nix append gotos here with: add rule inet filter input iffname ... goto ...
 150       }
 151       chain output {
 152         type filter hook output priority 0
 153         policy drop
 154
 155         oifname lo accept
 156
 157         ct state { related, established } accept
 158         ct state invalid counter drop
 159
 160         # ICMP
 161         ip protocol icmp counter accept
 162         ip6 nexthdr icmpv6 counter accept
 163
 164         tcp dport 22 counter accept comment "SSH"
 165
 166         # Some .nix append gotos here with: add rule inet filter output oifname ... goto ...
 167       }
 168       chain forward {
 169         type filter hook forward priority 0
 170         policy drop
 171       }
 172     }
 173   '';
 174 };
 175 }