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) networking;
   6   inherit (config.users) users groups;
   7 in
   8 {
   9 networking.firewall.enable = false;
  10 security.lockKernelModules = false;
  11 systemd.services.disable-kernel-module-loading.after = [ "nftables.service" ];
  12 systemd.services.nftables.serviceConfig.TimeoutStartSec = "20";
  13 networking.nftables = {
  14   enable = true;
  15   ruleset = lib.mkBefore ''
  16     table inet filter {
  17       # A set containing the udp port(s) to which SSDP replies are allowed.
  18       set ssdp_out {
  19         type inet_service
  20         timeout 5s
  21       }
  22       set lograte4 { type ipv4_addr; size 65535; flags dynamic; }
  23       set lograte6 { type ipv6_addr; size 65535; flags dynamic; }
  24       chain block {
  25         add @lograte4 { ip  saddr limit rate 1/minute } log level warn prefix "block: "
  26         add @lograte6 { ip6 saddr limit rate 1/minute } log level warn prefix "block: "
  27         counter drop
  28       }
  29       chain ping-flood {
  30         add @lograte4 { ip  saddr limit rate 1/minute } log level warn prefix "ping-flood: "
  31         add @lograte6 { ip6 saddr limit rate 1/minute } log level warn prefix "ping-flood: "
  32         counter drop
  33       }
  34       chain smurf {
  35         add @lograte4 { ip  saddr limit rate 1/minute } log level warn prefix "smurf: "
  36         add @lograte6 { ip6 saddr limit rate 1/minute } log level warn prefix "smurf: "
  37         counter drop
  38       }
  39       chain bogus-tcp {
  40         add @lograte4 { ip  saddr limit rate 1/minute } log level warn prefix "bogus-tcp: "
  41         add @lograte6 { ip6 saddr limit rate 1/minute } log level warn prefix "bogus-tcp: "
  42         counter drop
  43       }
  44       chain syn-flood {
  45         add @lograte4 { ip  saddr limit rate 1/minute } log level warn prefix "syn-flood: "
  46         add @lograte6 { ip6 saddr limit rate 1/minute } log level warn prefix "syn-flood: "
  47         counter drop
  48       }
  49       chain check-tcp {
  50         tcp flags syn tcp option maxseg size != 536-65535 counter goto bogus-tcp
  51         tcp flags & (ack|fin) == fin counter goto bogus-tcp
  52         tcp flags & (ack|psh) == psh counter goto bogus-tcp
  53         tcp flags & (ack|urg) == urg counter goto bogus-tcp
  54         tcp flags & (fin|ack) == fin counter goto bogus-tcp
  55         tcp flags & (fin|rst) == (fin|rst) counter goto bogus-tcp
  56         tcp flags & (fin|psh|ack) == (fin|psh) counter goto bogus-tcp
  57         tcp flags & (syn|fin) == (syn|fin) counter goto bogus-tcp comment "SYN-FIN scan"
  58         tcp flags & (syn|rst) == (syn|rst) counter goto bogus-tcp comment "SYN-RST scan"
  59         tcp flags == (fin|syn|rst|psh|ack|urg) counter goto bogus-tcp comment "XMAS scan"
  60         tcp flags == 0x0 counter goto bogus-tcp comment "NULL scan"
  61         tcp flags == (fin|urg|psh) counter goto bogus-tcp
  62         tcp flags == (fin|urg|psh|syn) counter goto bogus-tcp comment "NMAP-ID"
  63         tcp flags == (fin|urg|syn|rst|ack) counter goto bogus-tcp
  64
  65         ct state new tcp flags != syn counter goto bogus-tcp
  66         tcp sport 0 tcp flags & (fin|syn|rst|ack) == syn counter goto bogus-tcp
  67         tcp flags & (fin|syn|rst|ack) == syn counter limit rate over 30/second burst 60 packets goto syn-flood
  68       }
  69       chain net2fw {
  70         #udp dport mdns ip6 daddr ff02::fb counter accept comment "Accept mDNS"
  71         #udp dport mdns ip daddr 224.0.0.251 counter accept comment "Accept mDNS"
  72         #jump non-internet
  73
  74         #ct state new add @connlimit { ip saddr ct count over 20 } counter tcp reject with tcp reset
  75
  76         # Some .nix append rules here with: add rule inet filter net2fw ...
  77       }
  78       chain fw2net {
  79         tcp dport { 80, 443 } counter accept comment "HTTP"
  80         udp dport 123 skuid ${users.systemd-timesync.name} counter accept comment "NTP"
  81         tcp dport 1965 counter accept comment "Gemini"
  82         tcp dport 9418 counter accept comment "Git"
  83
  84         # Some .nix append rules here with: add rule inet filter fw2net ...
  85       }
  86       chain intra2fw {
  87         # Some .nix append rules here with: add rule inet filter intra2fw ...
  88       }
  89       chain fw2intra {
  90         # Some .nix append rules here with: add rule inet filter fw2intra ...
  91       }
  92       chain fwd-intra {
  93         # Some .nix append rules here with: add rule inet filter fwd-intra ...
  94       }
  95       chain extra2fw {
  96         # Some .nix append rules here with: add rule inet filter extra2fw ...
  97       }
  98       chain accept-icmpv6 {
  99         # Traffic That Must Not Be Dropped
 100         # https://tools.ietf.org/html/rfc4890#section-4.4.1
 101         icmpv6 type destination-unreachable counter accept
 102         icmpv6 type packet-too-big counter accept
 103         icmpv6 type time-exceeded counter accept
 104         icmpv6 type parameter-problem counter accept
 105
 106         # Address Configuration and Router Selection messages
 107         # (must be received with hop limit = 255)
 108         icmpv6 type nd-router-solicit ip6 hoplimit 255 counter accept
 109         ip6 nexthdr ipv6-icmp icmpv6 type nd-router-advert ip6 hoplimit 255 counter accept
 110         icmpv6 type nd-neighbor-solicit ip6 hoplimit 255 counter accept
 111         icmpv6 type nd-neighbor-advert ip6 hoplimit 255 counter accept
 112         icmpv6 type nd-redirect ip6 hoplimit 255 log level warn prefix "icmpv6: nd-redirect: " counter drop
 113         icmpv6 type ind-neighbor-solicit ip6 hoplimit 255 counter accept
 114         icmpv6 type ind-neighbor-advert ip6 hoplimit 255 counter accept
 115
 116         # Link-local multicast receiver notification messages
 117         # (must have link-local source address)
 118         icmpv6 type mld-listener-query ip6 saddr fe80::/10 counter accept
 119         icmpv6 type mld-listener-report ip6 saddr fe80::/10 counter accept
 120         icmpv6 type mld-listener-done ip6 saddr fe80::/10 counter accept
 121         # https://tools.ietf.org/html/rfc3810 Multicast Listener Discovery Version 2 (MLDv2) for IPv6
 122         icmpv6 type mld2-listener-report ip6 saddr fe80::/10 counter accept
 123
 124         # SEND Certificate Path notification messages
 125         # (must be received with hop limit = 255)
 126         icmpv6 type 148 ip6 hoplimit 255 counter accept comment "certificate-path-solicitation"
 127         icmpv6 type 149 ip6 hoplimit 255 counter accept comment "certificate-path-advertisement"
 128
 129         # Multicast Router Discovery messages
 130         # (must have link-local source address and hop limit = 1)
 131         icmpv6 type 151 ip6 saddr fe80::/10 ip6 hoplimit 1 counter accept comment "multicast-router-advertisement"
 132         icmpv6 type 152 ip6 saddr fe80::/10 ip6 hoplimit 1 counter accept comment "multicast-router-solicitation"
 133         icmpv6 type 153 ip6 saddr fe80::/10 ip6 hoplimit 1 counter accept comment "multicast-router-termination"
 134       }
 135
 136       chain input {
 137         type filter hook input priority filter
 138         policy drop
 139
 140         iifname lo accept
 141
 142         jump check-tcp
 143
 144         ct state { established, related } accept
 145
 146         # Connectivity checking messages
 147         # (multicast) ping
 148         ip protocol icmp icmp type echo-reply counter accept
 149
 150         ${lib.optionalString networking.enableIPv6 ''
 151         # drop packets with rh0 headers
 152         rt type 0 jump block
 153         rt type 0 jump block
 154         rt type 0 jump block
 155
 156         # (multicast) ping
 157         ip6 nexthdr ipv6-icmp icmpv6 type echo-reply counter accept
 158
 159         #ip6 daddr fe80::/64 udp dport 546 counter accept comment "DHCPv6"
 160         ''}
 161
 162         ct state invalid counter drop
 163
 164         ip protocol icmp icmp type destination-unreachable counter accept
 165         ip protocol icmp icmp type time-exceeded counter accept
 166         ip protocol icmp icmp type parameter-problem counter accept
 167         ip protocol icmp icmp type echo-request limit rate over 10/second burst 20 packets goto ping-flood
 168         ip protocol icmp icmp type echo-request counter accept
 169         # echo-reply is handled before invalid packets to allow multicast ping
 170         # which do not have an associated connection.
 171
 172         #ip daddr 224.0.0.251 udp dport 5353 counter accept comment "mDNS"
 173         #ip saddr 0.0.0.0/32 counter accept comment "DHCP"
 174         #ip udp sport 67 udp dport 68 counter accept comment "DHCP"
 175
 176         ${lib.optionalString networking.enableIPv6 ''
 177         ip6 nexthdr ipv6-icmp jump accept-icmpv6
 178
 179         # Connectivity checking messages
 180         icmpv6 type echo-request counter accept
 181         # echo-reply is handled before invalid because of multicast
 182
 183         ip6 nexthdr ipv6-icmp log level err prefix "net2fw: icmpv6: catch all: " counter reject
 184
 185         ip6 daddr ff02::fb udp dport 5353 counter accept comment "mDNS"
 186         ''}
 187
 188         ip saddr 224.0.0.0/4 counter goto smurf
 189         fib saddr type broadcast counter goto smurf
 190
 191         # admin services
 192         tcp dport 22 counter accept comment "SSH"
 193         udp dport 60000-61000 counter accept comment "Mosh"
 194
 195         # Some .nix append gotos here with: add rule inet filter input iffname ... goto ...
 196       }
 197       chain forward {
 198         type filter hook forward priority filter
 199         policy drop
 200
 201         ct state { related, established } accept
 202
 203         ip protocol icmp icmp type destination-unreachable counter accept
 204         ip protocol icmp icmp type time-exceeded counter accept
 205         ip protocol icmp icmp type parameter-problem counter accept
 206         ip protocol icmp icmp type echo-request counter accept
 207
 208         ${lib.optionalString networking.enableIPv6 ''
 209         # Traffic That Must Not Be Dropped
 210         # https://tools.ietf.org/html/rfc4890#section-4.3.1
 211         ip6 nexthdr ipv6-icmp icmpv6 type destination-unreachable counter accept
 212         ip6 nexthdr ipv6-icmp icmpv6 type packet-too-big counter accept
 213         ip6 nexthdr ipv6-icmp icmpv6 type time-exceeded counter accept
 214         ip6 nexthdr ipv6-icmp icmpv6 type parameter-problem counter accept
 215
 216         # Connectivity checking messages
 217         ip6 nexthdr ipv6-icmp icmpv6 type echo-request counter accept
 218         ip6 nexthdr ipv6-icmp icmpv6 type echo-reply counter accept
 219
 220         # Traffic That Normally Should Not Be Dropped
 221         # https://tools.ietf.org/html/rfc4890#section-4.3.2
 222         ip6 nexthdr ipv6-icmp icmpv6 type 144 counter accept comment "home-agent-address-discovery-request"
 223         ip6 nexthdr ipv6-icmp icmpv6 type 145 counter accept comment "home-agent-address-discovery-reply"
 224         ip6 nexthdr ipv6-icmp icmpv6 type 146 counter accept comment "mobile-prefix-solicitation"
 225         ip6 nexthdr ipv6-icmp icmpv6 type 147 counter accept comment "mobile-prefix-advertisement"
 226         ''}
 227       }
 228       chain output {
 229         type filter hook output priority filter
 230         policy drop
 231
 232         oifname lo accept
 233
 234         ct state { related, established } accept
 235
 236         ip protocol icmp counter accept
 237         meta skuid 0 udp dport 33434-33523 counter accept comment "traceroute"
 238
 239         ${lib.optionalString networking.enableIPv6 ''
 240         ip6 nexthdr ipv6-icmp jump accept-icmpv6
 241
 242         # Connectivity checking messages
 243         ip6 nexthdr ipv6-icmp icmpv6 type echo-request counter accept
 244         ip6 nexthdr ipv6-icmp icmpv6 type echo-reply counter accept
 245         ip6 nexthdr ipv6-icmp log level err prefix "fw2net: icmpv6: catch all: " counter reject
 246
 247         ip6 daddr ff02::1:2/64 udp dport 547 counter accept comment "DHCPv6"
 248         ''}
 249
 250         ct state invalid log level warn prefix "fw2net: invalid: " counter drop
 251
 252         tcp dport 22 counter accept comment "SSH"
 253
 254         # Some .nix append gotos here with: add rule inet filter output oifname ... goto ...
 255       }
 256     }
 257     table inet nat {
 258       chain prerouting {
 259         type nat hook prerouting priority filter
 260         policy accept
 261       }
 262       chain postrouting {
 263         type nat hook postrouting priority srcnat
 264         policy accept
 265       }
 266     }
 267   '';
 268 };
 269 }