nix/nixos/router.nix

{
  lib,
  # outputs,
  # config,
  pkgs,
  ...
}: let
  # NOTE: I could turn this into a cool NixOS module?
  # TODO: review https://francis.begyn.be/blog/nixos-home-router
  # TODO: more recent: https://github.com/ghostbuster91/blogposts/blob/a2374f0039f8cdf4faddeaaa0347661ffc2ec7cf/router2023-part2/main.md
  hostname = "router";
  domain = "h.lyte.dev";
  ip = "192.168.0.1";
  cidr = "${ip}/16";
  netmask = "255.255.255.0"; # see cidr
  dhcp_lease_space = {
    min = "192.168.0.30";
    max = "192.168.0.250";
  };
  interfaces = {
    wan = {
      name = "wan";
      mac = "00:01:2e:82:73:59";
    };
    lan = {
      name = "lan";
      mac = "00:01:2e:82:73:5a";
    };
  };
  hosts = {
    dragon = {
      ip = "192.168.0.10";
    };
    beefcake = {
      ip = "192.168.0.9";
      additionalHosts = [
        "nix.h.lyte.dev"
        "git.lyte.dev"
        "video.lyte.dev"
        "bw.lyte.dev"
        "files.lyte.dev"
        "vpn.h.lyte.dev"
      ];
    };
  };
  sysctl-entries = {
    "net.ipv4.conf.all.forwarding" = true;
    "net.ipv6.conf.all.forwarding" = true;

    "net.ipv4.conf.default.rp_filter" = 1;
    "net.ipv4.conf.${interfaces.wan.name}.rp_filter" = 1;
    "net.ipv4.conf.${interfaces.lan.name}.rp_filter" = 0;

    "net.ipv6.conf.${interfaces.wan.name}.accept_ra" = 2;
    "net.ipv6.conf.${interfaces.wan.name}.autoconf" = 1;
  };
in {
  imports = [
    {
      # hardware
      boot = {
        loader = {
          efi.canTouchEfiVariables = true;
          systemd-boot.enable = true;
        };
        initrd.availableKernelModules = ["xhci_pci"];
        initrd.kernelModules = [];
        kernelModules = ["kvm-intel"];
        extraModulePackages = [];
      };

      nixpkgs.hostPlatform = "x86_64-linux";
      powerManagement.cpuFreqGovernor = "performance";
      hardware.cpu.intel.updateMicrocode = true;
    }
  ];

  boot = {
    kernel = {
      sysctl = sysctl-entries;
    };
  };

  environment = {
    systemPackages = with pkgs; [
      wpa_supplicant
      inetutils
      btop
      htop
      bottom
      dog
    ];
  };

  networking = {
    hostName = hostname;
    domain = domain;

    useDHCP = false;
    nat.enable = false;
    firewall.enable = false;

    useNetworkd = true;

    extraHosts = ''
      127.0.0.1 localhost
      127.0.0.2 ${hostname}.${domain} ${hostname}
      ${ip} ${hostname}.${domain} ${hostname}

      ::1 localhost ip6-localhost ip6-loopback
      ff02::1 ip6-allnodes
      ff02::2 ip6-allrouters
    '';

    nftables = let
      inf = {
        lan = interfaces.lan.name;
        wan = interfaces.wan.name;
      };
    in {
      enable = true;
      ruleset = with inf; ''
        table inet filter {
        	set LANv4 {
        		type ipv4_addr
        		flags interval
        		elements = { 10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16, 169.254.0.0/16 }
        	}
        	set LANv6 {
        		type ipv6_addr
        		flags interval
        		elements = { fd00::/8, fe80::/10 }
        	}
          # TODO: maybe tailnet?

        	chain my_input_lan {
        		udp sport 1900 udp dport >= 1024 meta pkttype unicast limit rate 4/second burst 20 packets accept comment "Accept UPnP IGD port mapping reply"
        		udp sport netbios-ns udp dport >= 1024 meta pkttype unicast accept comment "Accept Samba Workgroup browsing replies"
        	}

          chain input {
            type filter hook input priority 0; policy drop;

        		iif lo accept comment "Accept any localhost traffic"
        		ct state invalid drop comment "Drop invalid connections"
        		ct state established,related accept comment "Accept traffic originated from us"

        		meta l4proto ipv6-icmp accept comment "Accept ICMPv6"
        		meta l4proto icmp accept comment "Accept ICMP"
        		ip protocol igmp accept comment "Accept IGMP"

            ip6 nexthdr icmpv6 icmpv6 type nd-router-solicit accept comment "Accept IPv6 router solicitation"
            ip6 nexthdr icmpv6 icmpv6 type nd-router-advert  accept comment "Accept IPv6 router advertisements"
            udp dport dhcpv6-client udp sport dhcpv6-server accept comment "IPv6 DHCP"

        		udp dport mdns ip6 daddr ff02::fb accept comment "Accept mDNS"
        		udp dport mdns ip daddr 224.0.0.251 accept comment "Accept mDNS"

        		tcp dport 2201 accept comment "Accept SSH on port 2201"
        		tcp dport 53 accept comment "Accept DNS"
        		udp dport 53 accept comment "Accept DNS"

        		ip6 saddr @LANv6 jump my_input_lan comment "Connections from private IP address ranges"
        		ip saddr @LANv4 jump my_input_lan comment "Connections from private IP address ranges"

            iifname "${lan}" accept comment "Allow local network to access the router"
            iifname "tailscale0" accept comment "Allow local network to access the router"
            iifname "${wan}" counter drop comment "Drop all other unsolicited traffic from wan"
          }

          chain forward {
            type filter hook forward priority filter; policy drop;

            iifname { "${lan}" } oifname { "${wan}" } accept comment "Allow trusted LAN to WAN"
            iifname { "tailscale0" } oifname { "${wan}" } accept comment "Allow trusted LAN to WAN"
            iifname { "${wan}" } oifname { "${lan}" } ct state { established, related } accept comment "Allow established back to LAN"
          }
        }

        table ip nat {
          chain prerouting {
            type nat hook prerouting priority dstnat;

          	iifname ${lan} accept
          	iifname tailscale0 accept

            iifname ${wan} tcp dport {22} dnat to ${hosts.beefcake.ip} comment "NAT SSH to beefcake"
            iifname ${wan} tcp dport {80, 443} dnat to ${hosts.beefcake.ip} comment "NAT HTTP/HTTPS to beefcake"
            iifname ${wan} tcp dport {25565, 26966} dnat to ${hosts.beefcake.ip} comment "NAT minecraft servers to beefcake"
          }

          chain postrouting {
            type nat hook postrouting priority 100; policy accept;
            oifname "${wan}" masquerade
          }
        }
      '';
    };

    # nftables.firewall = let
    #   me = config.networking.nftables.firewall.localZoneName;
    # in {
    #   enable = true;
    #   snippets.nnf-common.enable = true;

    #   zones = {
    #     ${interfaces.wan.name} = {
    #       interfaces = [interfaces.wan.name interfaces.lan.name];
    #     };
    #     ${interfaces.lan.name} = {
    #       parent = interfaces.wan.name;
    #       ipv4Addresses = [cidr];
    #     };
    #     # banned = {
    #     #   ingressExpression = [
    #     #     "ip saddr @banlist"
    #     #     "ip6 saddr @banlist6"
    #     #   ];
    #     #   egressExpression = [
    #     #     "ip daddr @banlist"
    #     #     "ip6 daddr @banlist6"
    #     #   ];
    #     # };
    #   };

    #   rules = {
    #     dhcp = {
    #       from = "all";
    #       to = [hosts.beefcake.ip];
    #       allowedTCPPorts = [67];
    #       allowedUDPPorts = [67];
    #     };
    #     http = {
    #       from = "all";
    #       to = [me];
    #       allowedTCPPorts = [80 443];
    #     };
    #     router-ssh = {
    #       from = "all";
    #       to = [me];
    #       allowedTCPPorts = [2201];
    #     };
    #     server-ssh = {
    #       from = "all";
    #       to = [hosts.beefcake.ip];
    #       allowedTCPPorts = [22];
    #     };
    #   };
    # };
  };

  systemd.network = {
    enable = true;
    # wait-online.anyInterface = true;

    links = {
      "20-${interfaces.wan.name}" = {
        enable = true;
        matchConfig = {
          MACAddress = interfaces.wan.mac;
        };
        linkConfig = {
          Name = interfaces.wan.name;
        };
      };
      "30-${interfaces.lan.name}" = {
        enable = true;
        matchConfig = {
          MACAddress = interfaces.lan.mac;
        };
        linkConfig = {
          Name = interfaces.lan.name;
        };
      };
    };
    networks = {
      "50-${interfaces.lan.name}" = {
        matchConfig.Name = "${interfaces.lan.name}";
        linkConfig = {
          RequiredForOnline = "enslaved";
          # Name = interfaces.lan.name;
        };

        address = [
          cidr
        ];
        networkConfig = {
          Description = "LAN network - connection to switch in house";
          ConfigureWithoutCarrier = true;
          IPv6AcceptRA = false;
          IPv6SendRA = true;
        };
      };
      "40-${interfaces.wan.name}" = {
        matchConfig.Name = "${interfaces.wan.name}";
        networkConfig = {
          Description = "WAN network - connection to fiber ISP jack";
          DHCP = "ipv4";
          IPv6AcceptRA = true;
          IPForward = true;
        };
        dhcpV6Config = {
          # ForceDHCPv6PDOtherInformation = true;
          UseHostname = false;
          UseDNS = false;
          UseNTP = false;
        };
        dhcpV4Config = {
          Hostname = hostname;
          UseHostname = false;
          UseDNS = false;
          UseNTP = false;
          UseSIP = false;
          UseRoutes = false;
          UseGateway = true;
        };
        linkConfig = {
          RequiredForOnline = "routable";
          # Name = interfaces.wan.name;
        };
        ipv6AcceptRAConfig = {
          DHCPv6Client = "always";
          UseDNS = false;
        };
      };
    };
  };

  services.resolved.enable = false;

  services.dnsmasq = {
    enable = true;
    settings = {
      listen-address = "::,127.0.0.1,${ip}";
      port = 53;

      # dhcp-authoritative = true;
      # dnssec = true;
      # enable-ra = true;

      server = ["1.1.1.1" "9.9.9.9" "8.8.8.8"];

      domain-needed = true;
      bogus-priv = true;
      no-resolv = true;

      cache-size = "10000";

      dhcp-range = with dhcp_lease_space; ["${interfaces.lan.name},${min},${max},${netmask},24h"];
      except-interface = interfaces.wan.name;
      interface = interfaces.lan.name;
      dhcp-host =
        [
        ]
        ++ (lib.attrsets.mapAttrsToList (name: {
          ip,
          identifier ? name,
          time ? "12h",
          ...
        }: "${name},${ip},${identifier},${time}")
        hosts);

      address =
        [
          "/${hostname}.${domain}/${ip}"
        ]
        ++ (lib.lists.flatten (lib.attrsets.mapAttrsToList (name: {
            ip,
            additionalHosts ? [],
            identifier ? name,
            time ? "12h",
          }: [
            "/${name}.${domain}/${ip}"
            (lib.lists.forEach additionalHosts (h: "/${h}/${ip}"))
          ])
          hosts));

      # local domains
      local = "/lan/";
      domain = "lan";
      expand-hosts = true;

      # don't use /etc/hosts as this would advertise surfer as localhost
      no-hosts = true;
    };
  };

  systemd.services.systemd-networkd-wait-online.enable = lib.mkForce false;

  services.openssh.listenAddresses = [
    {
      addr = "0.0.0.0";
      port = 2201;
    }
    {
      addr = "0.0.0.0";
      port = 22;
    }
    {
      addr = "[::]";
      port = 2201;
    }
    {
      addr = "[::]";
      port = 22;
    }
  ];

  # # services.fail2ban.enable = true;
  # services.radvd = {
  #   enable = false;
  #   # NOTE: this config is just the default arch linux config I think and may
  #   # need tweaking? this is what I had on the arch linux router, though :shrug:
  #   config = ''
  #     interface lo
  #     {
  #     	AdvSendAdvert on;
  #     	MinRtrAdvInterval 3;
  #     	MaxRtrAdvInterval 10;
  #     	AdvDefaultPreference low;
  #     	AdvHomeAgentFlag off;

  #     	prefix 2001:db8:1:0::/64
  #     	{
  #     		AdvOnLink on;
  #     		AdvAutonomous on;
  #     		AdvRouterAddr off;
  #     	};

  #     	prefix 0:0:0:1234::/64
  #     	{
  #     		AdvOnLink on;
  #     		AdvAutonomous on;
  #     		AdvRouterAddr off;
  #     		Base6to4Interface ppp0;
  #     		AdvPreferredLifetime 120;
  #     		AdvValidLifetime 300;
  #     	};

  #     	route 2001:db0:fff::/48
  #     	{
  #     		AdvRoutePreference high;
  #     		AdvRouteLifetime 3600;
  #     	};

  #       RDNSS 2001:db8::1 2001:db8::2
  #       {
  #         AdvRDNSSLifetime 30;
  #       };

  #       DNSSL branch.example.com example.com
  #       {
  #         AdvDNSSLLifetime 30;
  #       };
  #     };
  #   '';
  # };

  # services.resolved = {
  #   enable = false;
  #   extraConfig = ''
  #     [Resolve]
  #     DNSStubListener=no
  #   '';
  # };

  # services.dnsmasq = {
  #   enable = false;
  #   settings = {
  #     # server endpoints
  #     listen-address = "::1,127.0.0.1,${ip}";
  #     port = "53";

  #     # DNS cache entries
  #     cache-size = "10000";

  #     # local domain entries
  #     local = "/lan/";
  #     domain = "lan";
  #     expand-hosts = true;

  #     dhcp-authoritative = true;

  #     conf-file = "/usr/share/dnsmasq/trust-anchors.conf";
  #     dnssec = true;

  #     except-interface = "${wan_if}";
  #     interface = "${lan_if}";

  #     enable-ra = true;

  #     # dhcp-option = "121,${cidr},${ip}";

  #     dhcp-range = [
  #       "lan,${dhcp_lease_space.min},${dhcp_lease_space.max},${netmask},10m"
  #       "tag:${lan_if},::1,constructor:${lan_if},ra-names,12h"
  #     ];

  #     dhcp-host = [
  #       "${hosts.dragon.host},${hosts.dragon.ip},12h"
  #       "${hosts.beefcake.host},${hosts.beefcake.ip},12h"
  #     ];

  #     # may need to go in /etc/hosts (networking.extraHosts), too?
  #     address = [
  #       "/video.lyte.dev/192.168.0.9"
  #       "/git.lyte.dev/192.168.0.9"
  #       "/bw.lyte.dev/192.168.0.9"
  #       "/files.lyte.dev/192.168.0.9"
  #       "/vpn.h.lyte.dev/192.168.0.9"
  #       "/.h.lyte.dev/192.168.0.9"
  #     ];

  #     server = [
  #       "${ip}"
  #       "8.8.8.8"
  #       "8.8.4.4"
  #       "1.1.1.1"
  #       "1.0.0.1"
  #     ];
  #   };
  # };

  # nftables = {
  #   enable = false;
  #   flushRuleset = true;

  #   tables = {
  #     filter = {
  #       family = "inet";
  #       content = ''
  #         chain input {
  #           # type filter hook input priority filter; policy accept;
  #           type filter hook input priority 0;

  #           # anything from loopback interface
  #           iifname "lo" accept

  #           # accept traffic we originated
  #           ct state { established, related } counter accept
  #           ct state invalid counter drop

  #           # ICMP
  #           ip6 nexthdr icmpv6 icmpv6 type { echo-request, nd-neighbor-solicit, nd-neighbor-advert, nd-router-solicit, nd-router-advert, mld-listener-query, destination-unreachable, packet-too-big, time-exceeded, parameter-problem } counter accept
  #           ip protocol icmp icmp type { echo-request, destination-unreachable, router-advertisement, time-exceeded, parameter-problem } counter accept
  #           ip protocol icmpv6 counter accept
  #           ip protocol icmp counter accept
  #           meta l4proto ipv6-icmp counter accept

  #           udp dport dhcpv6-client counter accept

  #           tcp dport { 64022, 22, 53, 67, 25565 } counter accept
  #           udp dport { 64020, 22, 53, 67 } counter accept

  #           # iifname "iot" ip saddr $iot-ip tcp dport { llmnr } counter accept
  #           # iifname "iot" ip saddr $iot-ip udp dport { mdns, llmnr } counter accept
  #           iifname "${lan_if}" tcp dport { llmnr } counter accept
  #           iifname "${lan_if}" udp dport { mdns, llmnr } counter accept

  #           counter drop
  #         }

  #         # allow all outgoing
  #         chain output {
  #           type filter hook output priority 0;
  #           accept
  #         }

  #         chain forward {
  #           type filter hook forward priority 0;
  #           accept
  #         }
  #       '';
  #     };

  #     nat = {
  #       family = "ip";
  #       content = ''
  #         set masq_saddr {
  #         	type ipv4_addr
  #         	flags interval
  #         	elements = { ${cidr} }
  #         }

  #         map map_port_ipport {
  #         	type inet_proto . inet_service : ipv4_addr . inet_service
  #         }

  #         chain prerouting {
  #         	iifname ${lan_if} accept

  #         	type nat hook prerouting priority dstnat + 1; policy accept;
  #         	fib daddr type local dnat ip addr . port to meta l4proto . th dport map @map_port_ipport

  #         	iifname ${wan_if} tcp dport { 22, 80, 443, 25565, 64022 } dnat to ${hosts.beefcake.ip}
  #         	iifname ${wan_if} udp dport { 64020 } dnat to ${hosts.beefcake.ip}

  #         	# iifname ${wan_if} tcp dport { 25565 } dnat to 192.168.0.244
  #         	# iifname ${wan_if} udp dport { 25565 } dnat to 192.168.0.244

  #         	# router
  #         	iifname ${wan_if} tcp dport { 2201 } dnat to ${ip}
  #         }

  #         chain output {
  #         	type nat hook output priority -99; policy accept;
  #         	ip daddr != 127.0.0.0/8 oif "lo" dnat ip addr . port to meta l4proto . th dport map @map_port_ipport
  #         }

  #         chain postrouting {
  #         	type nat hook postrouting priority srcnat + 1; policy accept;
  #         	oifname ${lan_if} masquerade
  #         	ip saddr @masq_saddr masquerade
  #         }
  #       '';
  #     };
  #   };
  # };

  # dhcpcd = {
  #   enable = false;
  #   extraConfig = ''
  #     duid

  #     # No way.... https://github.com/NetworkConfiguration/dhcpcd/issues/36#issuecomment-954777644
  #     # issues caused by guests with oneplus devices
  #     noarp

  #     persistent
  #     vendorclassid

  #     option domain_name_servers, domain_name, domain_search
  #     option classless_static_routes
  #     option interface_mtu
  #     option host_name
  #     #option ntp_servers

  #     require dhcp_server_identifier
  #     slaac private
  #     noipv4ll
  #     noipv6rs

  #     static domain_name_servers=${ip}

  #     interface ${wan_if}
  #     	gateway
  #     	ipv6rs
  #     	iaid 1
  #     	# option rapid_commit
  #     	# ia_na 1
  #     	ia_pd 1 ${lan_if}

  #     interface ${lan_if}
  #     	static ip_address=${cidr}
  #     	static routers=${ip}
  #     	static domain_name_servers=${ip}
  #   '';
  # };
  # };
  # systemd.network = {
  #   enable = false;
  #   networks = {
  #     wan = {
  #       networkConfig = {
  #         DHCP = "yes";
  #       };
  #     };
  #     lan = {
  #       networkConfig = {
  #         DHCP = "yes";
  #       };
  #     };
  #   };
  #   links = {
  #     "10-${wan_if}" = {
  #       enable = true;
  #       matchConfig = {
  #         MACAddress = "00:01:2e:82:73:59";
  #       };
  #       linkConfig = {
  #         Name = wan_if;
  #       };
  #     };
  #     "10-${lan_if}" = {
  #       enable = true;
  #       matchConfig = {
  #         MACAddress = "00:01:2e:82:73:5a";
  #       };
  #       linkConfig = {
  #         Name = lan_if;
  #       };
  #     };
  #   };
  # };

  # services.avahi = {
  #   enable = lib.mkForce false;
  #   reflector = false;
  #   allowInterfaces = [lan_if];
  # };

  system.stateVersion = "24.05";
}