From 20dc8e5c5e24cea8d643726504b59166e987031a Mon Sep 17 00:00:00 2001
From: "quentin@aristote.fr" <quentin@aristote.fr>
Date: Sat, 8 Jun 2024 19:38:25 +0200
Subject: networking: dhcp: add bridge around enp3s0

---
 config/networking/bridges.nix       | 46 ++++++++++++++++++++++++++-----------
 config/networking/default.nix       |  6 ++---
 config/networking/services/dhcp.nix |  2 +-
 3 files changed, 36 insertions(+), 18 deletions(-)

(limited to 'config')

diff --git a/config/networking/bridges.nix b/config/networking/bridges.nix
index cdef41b..9e18ea8 100644
--- a/config/networking/bridges.nix
+++ b/config/networking/bridges.nix
@@ -1,26 +1,46 @@
-{ config, lib, utils, pkgs, ... }:
-
-let nets = config.personal.networking.networks;
+{
+  config,
+  lib,
+  pkgs,
+  ...
+}: let
+  nets = config.personal.networking.networks;
 in {
-  config = lib.mkMerge ([{
-    systemd.services.hostapd.postStart = lib.mkForce (lib.mkBefore ''
-      sleep 3
-    '');
-  }] ++ (builtins.map (network:
-    let
+  config = lib.mkMerge ([
+      {
+        systemd.services.hostapd.postStart = lib.mkForce (lib.mkBefore ''
+          sleep 3
+        '');
+      }
+      {
+        # create a bridge on top of enp3s0 along with a dummy interface
+        # for kea to work even when enp3s0 is disconnected
+        # if you change this, you may want to change:
+        # - the kea configuration in ./services/dhcp.nix
+        # - the eth0 net configuration ./default.nix
+        networking = {
+          bridges.eth0.interfaces = ["enp3s0" "enp3s0-dummy"];
+          localCommands = ''
+            ip link add enp3s0-dummy type dummy
+          '';
+        };
+        boot.kernelModules = ["dummy"];
+      }
+    ]
+    ++ (builtins.map (network: let
       bridge = network.interface;
       device = network.device;
     in {
-      networking.bridges."${bridge}".interfaces = [ ];
+      networking.bridges."${bridge}".interfaces = [];
 
       systemd.services."${bridge}-netdev".script = ''
         echo Setting forward delay to 0 for ${bridge}...
         ip link set ${bridge} type bridge forward_delay 0
       '';
 
-      systemd.services.hostapd.postStart = lib.mkForce (''
+      systemd.services.hostapd.postStart = lib.mkForce ''
         echo Setting ${device} to hairpin mode...
         ${pkgs.iproute2}/bin/bridge link set dev ${device} hairpin on
-      '');
-    }) [ nets.wan nets.iot ]));
+      '';
+    }) [nets.wan nets.iot]));
 }
diff --git a/config/networking/default.nix b/config/networking/default.nix
index 136be95..7ffc32b 100644
--- a/config/networking/default.nix
+++ b/config/networking/default.nix
@@ -93,11 +93,9 @@ in {
             };
           };
         };
-        eth0 = let
+        eth0 = {
           device = "enp3s0";
-        in {
-          inherit device;
-          interface = device;
+          interface = "eth0";
           subnet = "192.168.4";
           machines = {
             self.ip = "192.168.4.1";
diff --git a/config/networking/services/dhcp.nix b/config/networking/services/dhcp.nix
index 87ffc08..d27bbce 100644
--- a/config/networking/services/dhcp.nix
+++ b/config/networking/services/dhcp.nix
@@ -11,7 +11,7 @@ in {
   services.kea.dhcp4 = {
     enable = true;
     settings = let
-      subnets = with nets; [wan iot];
+      subnets = with nets; [wan iot eth0];
     in {
       interfaces-config = {
         interfaces = builtins.map (network: network.interface) subnets;
-- 
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