wasnotrice / nerves_network

Connect to wired and wireless networks on Nerves platforms.

README

Connect to wired and wireless networks on Nerves platforms.

General Installation (WiFi and Wired)

In your firmware's mix.exs, add nerves_network to your deps for your system target:

def deps(target) do
  [ system(target),
    {:nerves_network, "~> 0.3"}
  ]
end

Example Applications

nerves_examples has a networking example that can get you started.

nerves_init_gadget also sets can setup networking for wired ethernet connections and usb gadgets such as beaglebone boards and raspberry pi 0.

WiFi Networking

Installation and Setup

You'll first need to set the regulatory domain in your config.exs to your ISO 3166-1 alpha-2 country code. In theory this is optional, but you'll get the world regulatory domain ("00") which is the most restrictive. This may cause troubles when you try to connect to an access point.

config :nerves_network,
  regulatory_domain: "US"

The easiest way to get up and running is by statically setting your WiFi (and possibly ethernet) configuration in config.exs:

key_mgmt = System.get_env("NERVES_NETWORK_KEY_MGMT") || "WPA-PSK"

config :nerves_network, :default,
  wlan0: [
    ssid: System.get_env("NERVES_NETWORK_SSID"),
    psk: System.get_env("NERVES_NETWORK_PSK"),
    key_mgmt: String.to_atom(key_mgmt)
  ],
  eth0: [
    ipv4_address_method: :dhcp
  ]

If you are using an older version (< 0.3.0) of nerves_runtime then you'll need to do some additional setup to load the correct kernel module for WiFi. See this page for more information.

Scanning

You can scan by running:

iex> {:ok, _pid} = Nerves.Network.setup "wlan0"
iex> Nerves.Network.scan "wlan0"
[%{age: 42, beacon_int: 100, bssid: "00:1f:90:db:45:54", capabilities: 1073,
   flags: "[WEP][ESS]", freq: 2462, id: 8,
   ie: "00053153555434010882848b0c1296182403010b07",
   level: -83, noise: 0, qual: 0, ssid: "1SUT4", tsf: 580579066269},
 %{age: 109, beacon_int: 100, bssid: "00:18:39:7a:23:e8", capabilities: 1041,
   flags: "[WEP][ESS]", freq: 2412, id: 5,
   ie: "00076c696e6b737973010882848b962430486c0301",
   level: -86, noise: 0, qual: 0, ssid: "linksys", tsf: 464957892243},
 %{age: 42, beacon_int: 100, bssid: "1c:7e:e5:32:d1:f8", capabilities: 1041,
   flags: "[WPA2-PSK-CCMP][ESS]", freq: 2412, id: 0,
   ie: "000768756e6c657468010882848b960c1218240301",
   level: -43, noise: 0, qual: 0, ssid: "dlink", tsf: 580587711245}]

Runtime WiFi network setup

Setup your network connection by running:

Nerves.Network.setup "wlan0", ssid: "my_accesspoint_name", key_mgmt: :"WPA-PSK", psk: "secret"

If your WiFi network does not use a secret key, specify the key_mgmt to be :NONE.

If your WiFi network is using WEP connect by running:

  Nerves.Network.setup("wlan0", ssid: "wepnet", key_mgmt: :NONE, wep_key0: :"WEPSECRET", wep_tx_keyidx: 0)

Currently, wireless configuration passes almost unaltered to wpa_supplicant.ex, so see that project for more configuration options.

Note Nerves.Network.setup stores your interface's configuration information with SystemRegistry, which ties the configuration to the calling process. As such, if the process that called setup terminates, the network interface will lose its configuration information and be torn down. You can avoid this by calling setup in your application's start function, or by configuring nerves_network using shoehorn as described below.

Wired Networking

Wired networking setup varies in how IP addresses are expected to be assigned. The following examples show some common setups:

# Configure a network that supplies IP addresses via DHCP
Nerves.Network.setup "eth0", ipv4_address_method: :dhcp

# Statically assign an address
Nerves.Network.setup "eth0", ipv4_address_method: :static,
    ipv4_address: "10.0.0.2", ipv4_subnet_mask: "255.255.0.0",
    domain: "mycompany.com", nameservers: ["8.8.8.8", "8.8.4.4"]

# Assign a link-local address
Nerves.Network.setup "usb0", ipv4_address_method: :linklocal

Using nerves_network with shoehorn

Set default network interface settings as described above. Then you can use shoehorn to start nerves_network:

config :shoehorn,
  init: [:nerves_network],
  app: :your_app

Limitations

Currently, only IPv4 is supported. The library is incredibly verbose in its logging to help debug issues on new platforms in prep for a first release. This will change. The library is mostly interim in its structure. Please consider submitting PRs and helping make this work reliably across embedded devices.