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       set lograte4 { type ipv4_addr; size 65535; flags dynamic; }
  18       set lograte6 { type ipv6_addr; size 65535; flags dynamic; }
  19       chain block {
  20         add @lograte4 { ip  saddr limit rate 1/minute } log level warn prefix "block: "
  21         add @lograte6 { ip6 saddr limit rate 1/minute } log level warn prefix "block: "
  22         counter drop
  23       }
  24       chain ping-flood {
  25         add @lograte4 { ip  saddr limit rate 1/minute } log level warn prefix "ping-flood: "
  26         add @lograte6 { ip6 saddr limit rate 1/minute } log level warn prefix "ping-flood: "
  27         counter drop
  28       }
  29       chain smurf {
  30         add @lograte4 { ip  saddr limit rate 1/minute } log level warn prefix "smurf: "
  31         add @lograte6 { ip6 saddr limit rate 1/minute } log level warn prefix "smurf: "
  32         counter drop
  33       }
  34       chain bogus-tcp {
  35         add @lograte4 { ip  saddr limit rate 1/minute } log level warn prefix "bogus-tcp: "
  36         add @lograte6 { ip6 saddr limit rate 1/minute } log level warn prefix "bogus-tcp: "
  37         counter drop
  38       }
  39       chain syn-flood {
  40         add @lograte4 { ip  saddr limit rate 1/minute } log level warn prefix "syn-flood: "
  41         add @lograte6 { ip6 saddr limit rate 1/minute } log level warn prefix "syn-flood: "
  42         counter drop
  43       }
  44       chain check-tcp {
  45         tcp flags syn tcp option maxseg size != 536-65535 counter goto bogus-tcp
  46         tcp flags & (ack|fin) == fin counter goto bogus-tcp
  47         tcp flags & (ack|psh) == psh counter goto bogus-tcp
  48         tcp flags & (ack|urg) == urg counter goto bogus-tcp
  49         tcp flags & (fin|ack) == fin counter goto bogus-tcp
  50         tcp flags & (fin|rst) == (fin|rst) counter goto bogus-tcp
  51         tcp flags & (fin|psh|ack) == (fin|psh) counter goto bogus-tcp
  52         tcp flags & (syn|fin) == (syn|fin) counter goto bogus-tcp comment "SYN-FIN scan"
  53         tcp flags & (syn|rst) == (syn|rst) counter goto bogus-tcp comment "SYN-RST scan"
  54         tcp flags == (fin|syn|rst|psh|ack|urg) counter goto bogus-tcp comment "XMAS scan"
  55         tcp flags == 0x0 counter goto bogus-tcp comment "NULL scan"
  56         tcp flags == (fin|urg|psh) counter goto bogus-tcp
  57         tcp flags == (fin|urg|psh|syn) counter goto bogus-tcp comment "NMAP-ID"
  58         tcp flags == (fin|urg|syn|rst|ack) counter goto bogus-tcp
  59
  60         ct state new tcp flags != syn counter goto bogus-tcp
  61         tcp sport 0 tcp flags & (fin|syn|rst|ack) == syn counter goto bogus-tcp
  62         tcp flags & (fin|syn|rst|ack) == syn counter limit rate over 30/second burst 60 packets goto syn-flood
  63       }
  64       chain net2fw {
  65         #udp dport mdns ip6 daddr ff02::fb counter accept comment "Accept mDNS"
  66         #udp dport mdns ip daddr 224.0.0.251 counter accept comment "Accept mDNS"
  67         #jump non-internet
  68
  69         #ct state new add @connlimit { ip saddr ct count over 20 } counter tcp reject with tcp reset
  70
  71         # Some .nix append rules here with: add rule inet filter net2fw ...
  72       }
  73       chain fw2net {
  74         tcp dport { 80, 443 } counter accept comment "HTTP"
  75         udp dport 123 skuid ${users.systemd-timesync.name} counter accept comment "NTP"
  76         tcp dport 9418 counter accept comment "Git"
  77
  78         # Some .nix append rules here with: add rule inet filter fw2net ...
  79       }
  80       chain intra2fw {
  81         # Some .nix append rules here with: add rule inet filter intra2fw ...
  82       }
  83       chain fw2intra {
  84         # Some .nix append rules here with: add rule inet filter fw2intra ...
  85       }
  86       chain fwd-intra {
  87         # Some .nix append rules here with: add rule inet filter fwd-intra ...
  88       }
  89       chain accept-icmpv6 {
  90         # Traffic That Must Not Be Dropped
  91         # https://tools.ietf.org/html/rfc4890#section-4.4.1
  92         icmpv6 type destination-unreachable counter accept
  93         icmpv6 type packet-too-big counter accept
  94         icmpv6 type time-exceeded counter accept
  95         icmpv6 type parameter-problem counter accept
  96
  97         # Address Configuration and Router Selection messages
  98         # (must be received with hop limit = 255)
  99         icmpv6 type nd-router-solicit ip6 hoplimit 255 counter accept
 100         ip6 nexthdr ipv6-icmp icmpv6 type nd-router-advert ip6 hoplimit 255 counter accept
 101         icmpv6 type nd-neighbor-solicit ip6 hoplimit 255 counter accept
 102         icmpv6 type nd-neighbor-advert ip6 hoplimit 255 counter accept
 103         icmpv6 type nd-redirect ip6 hoplimit 255 log level warn prefix "icmpv6: nd-redirect: " counter drop
 104         icmpv6 type ind-neighbor-solicit ip6 hoplimit 255 counter accept
 105         icmpv6 type ind-neighbor-advert ip6 hoplimit 255 counter accept
 106
 107         # Link-local multicast receiver notification messages
 108         # (must have link-local source address)
 109         icmpv6 type mld-listener-query ip6 saddr fe80::/10 counter accept
 110         icmpv6 type mld-listener-report ip6 saddr fe80::/10 counter accept
 111         icmpv6 type mld-listener-done ip6 saddr fe80::/10 counter accept
 112         # https://tools.ietf.org/html/rfc3810 Multicast Listener Discovery Version 2 (MLDv2) for IPv6
 113         icmpv6 type mld2-listener-report ip6 saddr fe80::/10 counter accept
 114
 115         # SEND Certificate Path notification messages
 116         # (must be received with hop limit = 255)
 117         icmpv6 type 148 ip6 hoplimit 255 counter accept comment "certificate-path-solicitation"
 118         icmpv6 type 149 ip6 hoplimit 255 counter accept comment "certificate-path-advertisement"
 119
 120         # Multicast Router Discovery messages
 121         # (must have link-local source address and hop limit = 1)
 122         icmpv6 type 151 ip6 saddr fe80::/10 ip6 hoplimit 1 counter accept comment "multicast-router-advertisement"
 123         icmpv6 type 152 ip6 saddr fe80::/10 ip6 hoplimit 1 counter accept comment "multicast-router-solicitation"
 124         icmpv6 type 153 ip6 saddr fe80::/10 ip6 hoplimit 1 counter accept comment "multicast-router-termination"
 125       }
 126
 127       chain input {
 128         type filter hook input priority 0
 129         policy drop
 130
 131         iifname lo accept
 132
 133         jump check-tcp
 134
 135         ct state { established, related } accept
 136
 137         # Connectivity checking messages
 138         # (multicast) ping
 139         ip protocol icmp icmp type echo-reply counter accept
 140
 141         ${lib.optionalString networking.enableIPv6 ''
 142         # drop packets with rh0 headers
 143         rt type 0 jump block
 144         rt type 0 jump block
 145         rt type 0 jump block
 146
 147         # (multicast) ping
 148         ip6 nexthdr ipv6-icmp icmpv6 type echo-reply counter accept
 149
 150         #ip6 daddr fe80::/64 udp dport 546 counter accept comment "DHCPv6"
 151         ''}
 152
 153         ct state invalid counter drop
 154
 155         ip protocol icmp icmp type destination-unreachable counter accept
 156         ip protocol icmp icmp type time-exceeded counter accept
 157         ip protocol icmp icmp type parameter-problem counter accept
 158         ip protocol icmp icmp type echo-request limit rate over 10/second burst 20 packets goto ping-flood
 159         ip protocol icmp icmp type echo-request counter accept
 160         # echo-reply is handled before invalid packets to allow multicast ping
 161         # which do not have an associated connection.
 162
 163         #ip daddr 224.0.0.251 udp dport 5353 counter accept comment "mDNS"
 164         #ip daddr 239.255.255.250 udp dport 1900 counter accept comment "UPnP"
 165         #ip saddr 0.0.0.0/32 counter accept comment "DHCP"
 166         #ip udp sport 67 udp dport 68 counter accept comment "DHCP"
 167
 168         ${lib.optionalString networking.enableIPv6 ''
 169         ip6 nexthdr ipv6-icmp jump accept-icmpv6
 170
 171         # Connectivity checking messages
 172         icmpv6 type echo-request counter accept
 173         # echo-reply is handled before invalid because of multicast
 174
 175         ip6 nexthdr ipv6-icmp log level err prefix "net2fw: icmpv6: catch all: " counter accept
 176
 177         ip6 daddr ff02::fb udp dport 5353 counter accept comment "mDNS"
 178         ip6 daddr ff02::f udp dport 1900 counter accept comment "UPnP"
 179         ''}
 180
 181         ip saddr 224.0.0.0/4 counter goto smurf
 182         fib saddr type broadcast counter goto smurf
 183
 184         # admin services
 185         tcp dport 22 counter accept comment "SSH"
 186         udp dport 60000-61000 counter accept comment "Mosh"
 187
 188         # Some .nix append gotos here with: add rule inet filter input iffname ... goto ...
 189       }
 190       chain forward {
 191         type filter hook forward priority 0
 192         policy drop
 193
 194         ip protocol icmp icmp type destination-unreachable counter accept
 195         ip protocol icmp icmp type time-exceeded counter accept
 196         ip protocol icmp icmp type parameter-problem counter accept
 197         ip protocol icmp icmp type echo-request counter accept
 198
 199         ${lib.optionalString networking.enableIPv6 ''
 200         # Traffic That Must Not Be Dropped
 201         # https://tools.ietf.org/html/rfc4890#section-4.3.1
 202         ip6 nexthdr ipv6-icmp icmpv6 type destination-unreachable counter accept
 203         ip6 nexthdr ipv6-icmp icmpv6 type packet-too-big counter accept
 204         ip6 nexthdr ipv6-icmp icmpv6 type time-exceeded counter accept
 205         ip6 nexthdr ipv6-icmp icmpv6 type parameter-problem counter accept
 206
 207         # Connectivity checking messages
 208         ip6 nexthdr ipv6-icmp icmpv6 type echo-request counter accept
 209         ip6 nexthdr ipv6-icmp icmpv6 type echo-reply counter accept
 210
 211         # Traffic That Normally Should Not Be Dropped
 212         # https://tools.ietf.org/html/rfc4890#section-4.3.2
 213         ip6 nexthdr ipv6-icmp icmpv6 type 144 counter accept comment "home-agent-address-discovery-request"
 214         ip6 nexthdr ipv6-icmp icmpv6 type 145 counter accept comment "home-agent-address-discovery-reply"
 215         ip6 nexthdr ipv6-icmp icmpv6 type 146 counter accept comment "mobile-prefix-solicitation"
 216         ip6 nexthdr ipv6-icmp icmpv6 type 147 counter accept comment "mobile-prefix-advertisement"
 217         ''}
 218       }
 219       chain output {
 220         type filter hook output priority 0
 221         policy drop
 222
 223         oifname lo accept
 224
 225         ct state { related, established } accept
 226
 227         ip protocol icmp counter accept
 228         ip daddr 224.0.0.0/4 udp dport 1900 counter accept comment "UPnP"
 229
 230         ${lib.optionalString networking.enableIPv6 ''
 231         ip6 nexthdr ipv6-icmp jump accept-icmpv6
 232
 233         # Connectivity checking messages
 234         ip6 nexthdr ipv6-icmp icmpv6 type echo-request counter accept
 235         ip6 nexthdr ipv6-icmp icmpv6 type echo-reply counter accept
 236         ip6 nexthdr ipv6-icmp log level err prefix "fw2net: icmpv6: catch all: " counter accept
 237
 238         ip6 daddr ff02::1:2/64 udp dport 547 counter accept comment "DHCPv6"
 239         ''}
 240
 241         ct state invalid log level warn prefix "fw2net: invalid: " counter drop
 242
 243         tcp dport 22 counter accept comment "SSH"
 244
 245         # Some .nix append gotos here with: add rule inet filter output oifname ... goto ...
 246       }
 247     }
 248   '';
 249 };
 250 }