🍇 VintageNet

NOTE: This library is very much a work in progress without sufficient documentation. It will get there, but the current Nerves libraries are much more stable, tested for what they do, and integrated into most other Nerves libraries and examples. Most importantly, the official Nerves systems do not contain some of the programs and kernel configuration needed to make this work.

VintageNet is network configuration library built specifically for Nerves Project devices. It has the following features:

Ethernet and WiFi support included. Extendible to other technologies
Default configurations specified in your Application config
Runtime updates to configurations are persisted and applied on next boot (configurations are obfuscated by default to hide WiFi passphrases)
Simple subscription to network status change events
Connect to multiple networks at a time and prioritize which interfaces are used (Ethernet over WiFi over cellular)
Internet connection monitoring and failure detection (currently slow and simplistic)

The following network configurations are supported:

[x] Wired Ethernet, IPv4 DHCP
[ ] Wired Ethernet, IPv4 static IP
[x] WiFi password-less and WEP
[x] WPA2 PSK and EAP
[ ] USB gadget mode Ethernet, IPv4 DHCP server to supply host IP address
[ ] Cellular networks
[x] WiFi AP mode
[ ] IPv6

VintageNet takes a different approach to networking from nerves_network. It supports calling "old school" Linux utilities like ifup and ifdown to configure networks. While this isn't ideal, some network configurations are only documented for Linux systems and this can be a huge timesaver for getting an unusual network configuration working. VintageNet supports a migration path to pulling configuration back into Elixir piecemeal. Additionally, VintageNet doesn't attempt to make incremental modifications to configurations. It completely tears down an interface's connection and then brings up new configurations in a fresh state. Network reconfiguration is assumed to be an infrequent event so while this can cause a hiccup in the network connectivity, it removes most of the state machine code that made nerves_network hard to maintain.

Installation

The vintage_net and nerves_init_gadget packages are not compatible. If you are using nerves_init_gadget, you will need to remove it from your dependency list and add back in things it supplies like nerves_runtime and nerves_firmware_ssh.

When available in Hex, the package can be installed by adding vintage_net to your list of dependencies in mix.exs:

def deps do
  [
    {:vintage_net, "~> 0.1.0", targets: @all_targets}
  ]
end

Erlang/OTP provides many libraries for debugging networking issues. You may also want to add Toolshed to your dependencies so that you can have more familiar looking tools like ifconfig and ping at the IEx prompt.

Configuration

VintageNet has many application configuration keys. Most defaults are fine. At a minimum, you'll want to specify a default configuration and default regulatory domain if using WiFi. In your main config.exs, add the following:

config :vintage_net,
  regulatory_domain: "US",
  config: [
    {"eth0", %{type: VintageNet.Technology.Ethernet, ipv4: %{method: :dhcp}}},
    {"wlan0", %{type: VintageNet.Technology.WiFi}}
  ]

This sets the regulatory domain to the US (set to your ISO 3166-1 alpha-2 country code. This code is passed on to the drivers for WiFi and other wireless networking technologies so that they comply with local regulations. If you need a global default, set to "00" or don't set at all. Unfortunately, this may mean that an access point isn't visible if it is running on a frequency that's allowed in your country, but not globally.

The config section is a list of network configurations. The one shown above configures DHCP on wired Ethernet and minimally starts up a WiFi LAN so that it's possible to scan for networks. Details on network configuration are described later.

The following table describes the other application config keys.

Key	Description
config	A list of default network configurations
tmpdir	Path to a temporary directory for VintageNet
to_elixir_socket	Name to use for the Unix domain socket for C to Elixir communication
bin_ifup	Path to `ifup`
bin_ifdown	Path to `ifdown`
bin_chat	Path to `chat`
bin_pppd	Path to `pppd`
bin_mknod	Path to `mknod`
bin_killall	Path to `killall`
bin_wpa_supplicant	Path to `wpa_supplicant`
bin_wpa_cli	Path to `wpa_cli`
bin_ip	Path to `ip`
udhcpc_handler	Module for handling notifications from `udhcpc`
resolvconf	Path to `/etc/resolv.conf`
persistence	Module for persisting network configurations
persistence_dir	Path to a directory for storing persisted configurations
persistence_secret	A 16-byte secret or an MFA for getting a secret
internet_host	IP address for host to `ping` to check for Internet connectivity
regulatory_domain	ISO 3166-1 alpha-2 country (`00` for global, `US`, etc.)

Network interface configuration

VintageNet supports several network technologies out of the box and third-party libraries can provide more via the VintageNet.Technology behaviour.

Configurations are Elixir maps. These are specified in three places:

The vintage_net application config (e.g., your config.exs)
Locally saved configuration (see the VintageNet.Persistence behaviour for replacing the default)
Calling VintageNet.configure/2 to change the configuration at run-time

When vintage_net starts, it applies saved configurations first and if any thing is wrong with those configs, it reverts to the application config. A good practice is to have safe defaults for all network interfaces in the application config.

The only required key in the configuration maps is :type. All other keys follow from the type. :type should be set to a module that implements the VintageNet.Technology behaviour. The following are included:

VintageNet.Technology.Ethernet - Standard wired Ethernet
VintageNet.Technology.WiFi - Client configurations for 802.11 WiFi
VintageNet.Technology.Mobile - Cellular configurations (likely to be refactored to a separate library)
VintageNet.Technology.Null - An empty configuration useful for turning off a configuration

The following sections describe the types in more detail.

Wired Ethernet

Wired Ethernet interfaces typically have names like "eth0", "eth1", etc. when using Nerves.

Currently only IPv4 support using DHCP is supported:

%{type: VintageNet.Technology.Ethernet, ipv4: %{method: :dhcp}}

For example, to set the configuration at runtime:

iex> VintageNet.configure("eth0", %{type: VintageNet.Technology.Ethernet, ipv4: %{method: :dhcp}})
:ok

Wired Ethernet connections are monitored for Internet connectivity. When internet-connected, they are preferred over all other network technologies even when the others provide default gateways.

WiFi

WiFi network interfaces typically have names like "wlan0" or "wlan1" when using Nerves. Most of the time, there's only one WiFi interface and its "wlan0". Some WiFi adapters expose separate interfaces for 2.4 GHz and 5 GHz and they can be configured independently.

WiFi configuration looks like this:

%{
  type: VintageNet.Technology.WiFi,
  wifi: %{
    key_mgmt: :wpa_psk,
    mode: :client,
    psk: "a_passphrase_or_psk",
    ssid: "my_network_ssid"
  },
  ipv4: %{method: :dhcp}
}

The :ipv4 key is the same as in Wired Ethernet and only DHCP is currently supported.

The :wifi key has the following common fields:

:key_mgmt - WiFi security mode (:wpa_psk for WPA2, :none for no password)
:mode -
- :client (default) - Normal operation. Associate with an AP
- :adhoc - peer to peer mode
- :host - access point mode
:psk - A WPA2 passphrase or the raw PSK. If a passphrase is passed in, it will be converted to a PSK and disgarded.
:ssid - The SSID for the network

See the official docs for the complete list of options.

Here's an example:

iex> VintageNet.configure("wlan0", %{
      type: VintageNet.Technology.WiFi,
      wifi: %{
        key_mgmt: :wpa_psk,
        mode: :client,
        psk: "a_passphrase_or_psk",
        ssid: "my_network_ssid"
      },
      ipv4: %{method: :dhcp}
    })

Example of WEP:

iex> VintageNet.configure("wlan0", %{
      type: VintageNet.Technology.WiFi,
      wifi: %{
        ssid: "my_network_ssid",
        wep_key0: "42FEEDDEAFBABEDEAFBEEFAA55",
        key_mgmt: :none,
        wep_tx_keyidx: 0
      },
      ipv4: %{method: :dhcp}
    })

Example of WPA-EAP:

iex> VintageNet.configure("wlan0", %{
      type: VintageNet.Technology.WiFi,
      wifi: %{
        ssid: "testing",
        key_mgmt: :wpa_eap,
        scan_ssid: 1,
        pairwise: "CCMP TKIP",
        group: "CCMP TKIP",
        eap: "PEAP",
        identity: "user1",
        password: "supersecret",
        phase1: "peapver=auto",
        phase2: "MSCHAPV2"
      },
      ipv4: %{method: :dhcp}
})

Example of access point mode:

iex> VintageNet.configure("wlan0", %{
      type: VintageNet.Technology.WiFi,
      wifi: %{
        mode: :host,
        ssid: "test ssid",
        key_mgmt: :none
      },
      ipv4: %{
        method: :static,
        address: "192.168.24.1",
        netmask: "255.255.255.0",
        gateway: "192.168.24.1"
      },
      dhcpd: %{
        start: "192.168.24.2",
        end: "192.168.24.10"
      }
})

LTE

Properties

VintageNet maintains a key/value store for retrieving information on networking information:

iex> VintageNet.get(["interface", "eth0", "connection"])
:internet

iex> VintageNet.get_by_prefix([])
[
  {["interface", "eth0", "connection"], :internet},
  {["interface", "eth0", "state"], "configured"},
  {["interface", "eth0", "type"], VintageNet.Technology.Ethernet},
  {["interface", "wlan0", "connection"], :internet},
  {["interface", "wlan0", "state"], "configured"},
  {["interface", "wlan0", "type"], VintageNet.Technology.WiFi}
]

You can also subscribe to keys and receive a message every time it or one its child keys changes:

iex> VintageNet.subscribe(["interface", "eth0"])
:ok

iex> flush
{VintageNet, ["interface", "eth0", "state"], "configuring", "configured", %{}}

The message format is {VintageNet, name, old_value, new_value, metadata}

Global properties

Property	Values	Description
`available_interfaces`	`[eth0, ...]`	Currently available network interfaces in priority order. E.g., the first one is used by default

Common network interface properties

All network interface properties can be found under ["interface", ifname] in the PropertyTable. The following table lists out properties common to all interfaces:

Property	Values	Description
`type`	`Ethernet`, etc.	The type of the interface
`state`	`configured`, `configuring`, etc.	The state of the interface from `VintageNet`'s point of view.
`connection`	`disconnected`, `lan`, `internet`	This provides a determination of the Internet connection status
`ipv4`	IPv4 parameters	This is a map of IPv4 parameters on the interface. This includes IP address, subnet, gateway, etc.

Specific types of interfaces provide more parameters.

Wired Ethernet status

No additional parameters

WiFi status

Property	Values	Description

LTE status

Property	Values	Description
`signal`	0 - 100	This is a rough measure of signal strength from 0 (none) to 100 (all bars)

System Requirements

Busybox Requirements

CONFIG_UDHCPC=y - udhcpc DHCP Client
CONFIG_UDHCPD=y - udhcpd DHCP Server (optional)
CONFIG_IFUP=y - ifup
CONFIG_IFDOWN=y ifdown
CONFIG_RUN_PARTS=y
CONFIG_MKTEMP=y

Buildroot Requirements

BR2_PACKAGE_WPA_SUPPLICANT
BR2_PACKAGE_WPA_SUPPLICANT_CLI

Additional Requirements for Access Point Mode

BR2_PACKAGE_DNSMASQ or CONFIG_UDHCPD (in busybox)
BR2_PACKAGE_HOSTAPD or BR2_PACKAGE_WPA_SUPPLICANT_HOTSPOT

Additional Requirements for LTE

Kernel modules (defconfig)

CONFIG_PPP=m
CONFIG_PPP_BSDCOMP=m
CONFIG_PPP_DEFLATE=m
CONFIG_PPP_ASYNC=m
CONFIG_PPP_SYNC_TTY=m
CONFIG_USB_NET_CDC_NCM=m
CONFIG_USB_NET_HUAWEI_CDC_NCM=m
CONFIG_USB_SERIAL_OPTION=m

System deps

pppd
mknod

v0.2.0