doc WIP: build "hello net" example

examples/hellonet.nix

@@ -0,0 +1,50 @@
+{ config, pkgs, lib, ... } :
+let
+  inherit (pkgs) serviceFns;
+  svc = config.system.service;
+
+in rec {
+  imports = [
+    ../modules/network
+    ../modules/dnsmasq
+    ../modules/ntp
+    ../modules/ssh
+  ];
+  hostname = "hellonet";
+
+  services.int = svc.network.address.build {
+    interface = config.hardware.networkInterfaces.lan;
+    family = "inet"; address ="10.3.0.1"; prefixLength = 16;
+  };
+
+  services.ntp = svc.ntp.build {
+    pools = { "pool.ntp.org" = ["iburst"]; };
+    makestep = { threshold = 1.0; limit = 3; };
+  };
+
+  services.sshd = svc.ssh.build { };
+
+  users.root = {
+    passwd = "";
+  };
+
+  services.dns =
+    let interface = services.int;
+    in svc.dnsmasq.build {
+      inherit interface;
+      ranges = [
+        "10.3.0.10,10.3.0.240"
+        # ra-stateless: sends router advertisements with the O and A
+        # bits set, and provides a stateless DHCP service. The client
+        # will use a SLAAC address, and use DHCP for other
+        # configuration information.
+        "::,constructor:$(output ${interface} ifname),ra-stateless"
+      ];
+
+      domain = "example.org";
+    };
+
+  defaultProfile.packages = with pkgs; [
+    figlet
+  ];
+}