shinobu/router: Add network segmentation

machines/shinobu/services/router/common.nix

@@ -1,6 +1,55 @@
-{ ... }:
+{ lib, ... }:
+let
+  mkSubnet = v4: v6:
+    let
+      splitCidr = lib.splitString "/";
+      fst = lib.flip lib.elemAt 0;
+      snd = lib.flip lib.elemAt 1;
+
+      v4Split = splitCidr v4;
+      v6Split = splitCidr v6;
+    in
+    {
+      v4 = rec {
+        cidr = v4;
+        net = fst v4Split;
+        suffix = snd v4Split;
+        withoutLastComponent = lib.substring 0 ((lib.stringLength net) - 1) net;
+        gateway = "${withoutLastComponent}1";
+        gatewayCidr = "${gateway}/${suffix}";
+      };
+      v6 = rec {
+        cidr = v6;
+        net = fst v6Split;
+        suffix = snd v6Split;
+        gateway = "${net}1";
+        gatewayCidr = "${gateway}/${suffix}";
+      };
+    };
+in
 {
+  vlan = {
+    lan = {
+      id = 10;
+      subnet = mkSubnet "10.80.1.0/24" "fd00:80:1::/64";
       domain = "home.sbruder.de";
+    };
+    management = {
+      id = 20;
+      subnet = mkSubnet "10.80.2.0/24" "fd00:80:2::/64";
+      domain = "management.sbruder.de";
+    };
+    guest = {
+      id = 30;
+      subnet = mkSubnet "10.80.3.0/24" "fd00:80:3::/64";
+      domain = "guest.sbruder.de";
+    };
+    iot = {
+      id = 40;
+      subnet = mkSubnet "10.80.4.0/24" "fd00:80:4::/64";
+      domain = "iot.sbruder.de";
+    };
+  };
   tc = {
     interface = "enp1s0";
     # 4160 kbit is slightly smaller than the average upload

machines/shinobu/services/router/default.nix

@@ -1,26 +1,22 @@
 # Home network configuration
-#            (2.5GbE clients)
+#
-#                  | |
+#     +----------+ +------------+
-#     +----------+ +----------+
+#     |          | |            | (clients)#  (guests)
-#     |          | | | |      | (1GbE clients)
+#     |          | |         +--|--|--|--|-#+-|--|--|-|-unused|
-#     |          | | | |     +|-|-|-|-|+
+# +---+----+   +-+-+-+-+-+   | 01 02 …… 12 # 13 …… 24 | 25 26 |
-# +---+----+   +-+-+-+-+-+   |5 4 3 2 1|
+# |upstream|   | 1 2 3 4 |   | aruba Instant On 1830  | (SFP) |
-# |upstream|   | 1 2 3 4 |   |TL-SG105 |
+# +--------+   | shinobu |   +------------------------+-------+
-# +--------+   | shinobu |   +---------+
 #              +---------+
 #
 # It consists of shinobu as a router (this configuration),
-# connected to a TP-LINK TL-SG105E “smart managed” (i.e., it can do VLANs) 5-port switch.
+# connected to a aruba (HPE) Instant ON 1830 24-port 1GbE switch.
 # The upstream comes (for now) from a PŸUR “WLAN-Kabelbox” (Compal CH7467CE).
 # Sadly, I could not enable bridge mode on it, so the packets now go through (at least) three layers of NAT:
 # device → NAT on shinobu → NAT on plastic router → PŸUR CGNAT
 #
-# Because the switch only supports GbE,
+# Because of issues with the NICs operating at 2.5GbE,
-# the two clients I currently have with support for 2.5GbE are connected
+# all clients are connected to the switch,
-# directly to the two remaining network interfaces on shinobu.
+# even if they have a 2.5GbE NIC.
-# Once I have more devices with support for 2.5GbE
-# or I find a good deal on a matching switch,
-# I will change this.
 #
 # Wireless is configured by providing the whole hostapd configuration file as a secret.
 # Once nixpkgs PR 222536 is merged, I will migrate to using the NixOS module.
@@ -52,15 +48,48 @@ in
     enable = true;
     # not all interfaces need to be up
     wait-online.extraArgs = [ "--any" ];
-    netdevs = {
+    netdevs = lib.mkMerge [
-      br-lan = {
+      (lib.mapAttrs
+        (name: config: {
           netdevConfig = {
-          Name = "br-lan";
+            Kind = "vlan";
+            Name = name;
+          };
+          vlanConfig = {
+            Id = config.id;
+          };
+        })
+        cfg.vlan)
+      (lib.mapAttrs'
+        (name: config: lib.nameValuePair "br-${name}" {
+          netdevConfig = {
+            Name = "br-${name}";
             Kind = "bridge";
           };
+        })
+        cfg.vlan)
+    ];
+    networks = lib.mkMerge [
+      (lib.mapAttrs
+        (name: config: {
+          inherit name;
+          matchConfig = {
+            Type = "vlan";
           };
+          bridge = [ "br-${name}" ];
+        })
+        cfg.vlan)
+      (lib.mapAttrs'
+        (name: config: lib.nameValuePair "br-${name}" {
+          name = "br-${name}";
+          domains = [ config.domain ];
+          address = lib.mapAttrsToList (family: familyConfig: familyConfig.gatewayCidr) config.subnet;
+          networkConfig = {
+            IPv6AcceptRA = false;
           };
-    networks = {
+        })
+        cfg.vlan)
+      {
         wan = {
           name = "enp1s0";
           DHCP = "ipv4";
@@ -76,9 +105,17 @@ in
             UseDNS = "no";
           };
         };
-      lan1 = {
+        physical-lan = {
           name = "enp2s0";
-        bridge = [ "br-lan" ];
+          vlan = lib.attrNames cfg.vlan;
+          # no autoconfiguration needed, only tagged VLAN
+          networkConfig = {
+            LinkLocalAddressing = "no";
+            LLDP = "no";
+            EmitLLDP = "no";
+            IPv6AcceptRA = "no";
+            IPv6SendRA = "no";
+          };
         };
         lan2 = {
           name = "enp3s0";
@@ -88,12 +125,8 @@ in
           name = "enp4s0";
           bridge = [ "br-lan" ];
         };
-      br-lan = {
+      }
-        name = "br-lan";
+    ];
-        domains = [ cfg.domain ];
-        address = [ "10.80.1.1/24" "fd00:80:1::1/64" ];
-      };
-    };
   };
   services.resolved.enable = false;
 }

machines/shinobu/services/router/dnsmasq.nix

@@ -1,4 +1,4 @@
-{ config, pkgs, ... }:
+{ config, lib, pkgs, ... }:
 let
   cfg = pkgs.callPackage ./common.nix { };
 in
@@ -9,35 +9,39 @@ in
     settings = {
       bogus-priv = true; # do not forward revese lookups of internal addresses
       domain-needed = true; # do not forward names without domain
-      interface = "br-lan"; # only respond to queries from lan
+      interface = lib.mapAttrsToList (name: config: "br-${name}") cfg.vlan; # only respond to queries from own interfaces
       no-hosts = true; # do not resolve hosts from /etc/hosts
       no-resolv = true; # only use explicitly configured resolvers
+      dhcp-fqdn = true; # only insert qualified names of DHCP clients into DNS
 
       cache-size = 10000;
 
-      inherit (cfg) domain;
+      domain = [
+        "invalid.sbruder.de" # used when no rule below matches
+      ] ++ (lib.flatten (lib.mapAttrsToList
+        (name: { domain, subnet, ... }: [
+          "${domain},br-${name}" # only this is not enough
+          "${domain},${subnet.v4.cidr}"
+          "${domain},${subnet.v6.cidr}"
+        ])
+        cfg.vlan));
 
       # Allow resolving the router
-      interface-name = [
+      interface-name = lib.mapAttrsToList (name: { domain, ... }: "${config.networking.hostName}.${domain},br-${name}") cfg.vlan;
-        "${config.networking.hostName}.${cfg.domain},br-lan"
-        "${config.networking.hostName},br-lan"
-      ];
 
-      # DHCPv4
+      dhcp-range = lib.flatten (lib.mapAttrsToList
-      dhcp-range = [
+        (name: { subnet, ... }: [
-        "10.80.1.20,10.80.1.150,12h" # DHCPv4
+          "tag:br-${name},${subnet.v4.withoutLastComponent}2,${subnet.v4.withoutLastComponent}254,12h" # DHCPv4
-        "fd00:80:1::,ra-stateless,ra-names" # SLAAC (for addresses) / DHCPv6 (for DNS)
+          "tag:br-${name},${subnet.v6.net},ra-stateless,ra-names" # SLAAC (for addresses) / DHCPv6 (for DNS)
-      ];
+        ])
-      dhcp-option = [
+        cfg.vlan);
-        "option:router,10.80.1.1"
+      dhcp-option = lib.flatten (lib.mapAttrsToList
-        "option6:dns-server,fd00:80:1::1"
+        (name: { subnet, ... }: [
-      ];
+          "tag:br-${name},option:router,${subnet.v4.gateway}"
+          "tag:br-${name},option6:dns-server,${subnet.v6.gateway}"
+        ])
+        cfg.vlan);
 
-      # Despite its name, the switch does not have a “smart” configuration,
-      # that would allow me to tell it not to get DHCP from wan,
-      # but from lan instead.
-      # So it has to use static configuration.
-      host-record = "switchviech,switchviech.${cfg.domain},10.80.1.19";
       server = [
         "127.0.0.1#5053"
       ];

machines/shinobu/services/router/nft.nix

@@ -10,7 +10,10 @@ let
         else lib.generators.mkValueStringDefault { } v;
     } " = ";
 
-  passthru = { };
+  passthru = {
+    VLANS = lib.attrNames cfg.vlan;
+    VLAN_BRIDGES = map (name: "br-${name}") (lib.attrNames cfg.vlan);
+  };
 
   defines = lib.concatStringsSep
     "\n"

machines/shinobu/services/router/rules.nft

@@ -1,4 +1,4 @@
-define NAT_LAN_IFACES = { "br-lan" }
+define NAT_LAN_IFACES = { "br-lan", "br-guest" }
 define PHYSICAL_WAN = "enp1s0"
 define NAT_WAN_IFACES = { $PHYSICAL_WAN }
 
@@ -6,9 +6,20 @@ table inet filter {
 	chain forward {
 		type filter hook forward priority filter; policy drop
 
-		# allow traffic between lan and wan
+		# plastic router, might be vulnerable (FIXME v6 is still reachable)
+		iifname "br-guest" ip daddr "192.168.0.1" drop
+
+		# allow traffic between selected VLANs and wan
 		iifname $NAT_LAN_IFACES oifname $NAT_WAN_IFACES counter accept
 		iifname $NAT_WAN_IFACES oifname $NAT_LAN_IFACES ct state established,related counter accept
+
+		# traffic from lan to all other vlans is allowed
+		iifname "br-lan" oifname $VLAN_BRIDGES counter accept;
+		iifname $VLAN_BRIDGES oifname "br-lan" ct state established,related counter accept
+
+		iifname "br-iot" ip daddr 167.235.30.249 tcp dport 1883 counter accept # FIXME migrate service to shinobu
+		iifname "br-iot" udp dport 123 counter accept # FIXME too generic
+		iifname $NAT_WAN_IFACES oifname "br-iot" ct state established,related counter accept
 	}
 }