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Ethernet

Manages ethernet on Nerves based embedded systems, with optional Celluose integration.

Features

  • DHCP, including timeouts and re-acquisition
  • IP4LL/AIPA automatic ethernet address configuration
  • Easy callback-based notification of device state changes

Usage

{:ok, eth0} = Ethernet.start_link interface: "eth0", hostname: "happy"

Options are specified by a keyword list, as follows:

keyword type description
interface string interface to configure (eg "eth0", "en2", "lo0", etc)
hostname string hostname to pass to dhcp server during dhcp request

Config options may be specified by a keyword list for configuration in a config.exs file using the :static_config key. Required keys of list are:

keyword type description
ip string IP address to configure to (e.g. "192.168.15.100")
mask string Subnet Mask to use (e.g. "255.255.255.0")
router string IP address of router (e.g. "192.168.15.1") 
config :ethernet, static_config: [
    ip: "192.168.1.10",
    mask: "255.255.0.0",
    router: "192.168.1.1"
    ]

Notifications

Ethernet implements an event manager which provides information about changes in the status of the interface.

For instance, imagine you wanted to implement a handler that wrote the new network configuration to standard output everytime it changed. You could implement it like this:

defmodule NetworkStateInspectionHandler
  use GenEvent
  def handle_event(:if_changed, new_config) do
    IO.write "New configuration: #{inspect new_config}"
  end
end

And then, you could start the interface and add the handler like this..

{:ok, eth0} = Ethernet.start_link interface: "eth0", hostname: "happy"
GenEvent.add_handler(eth0, NetworkStateInspectionHandler, [])

Static IP Configuration Storage

Ethernet is capable of storing static configuration values, provided a module is implemented following the Ethernet.Storage Behaviour. It is up to the implementer to determine how this should be accomplished. An example of using cellulose/persistent_storage project is provided in the /examples directory.

To utilize your module just specify it in your config:

config :ethernet, storage: EthernetPersistentStorage

Or when you start Ethernet just pass it with the key :storage:

Ethernet.start storage: EthernetPersistentStorage

Areas For Improvement

  • needs a lot better AIPA/IP4LL address negotiation

Examples

    # Start Ethernet using dhcp and calling back to AIPA/ipv4ll

    #config.exs
    config :ethernet, interface: "eth2", hostname: "bbb"

    # starting...
    iex> Ethernet.start

    # Start Ethernet with static configuration

    #config.exs
    config :ethernet, interface: "eth2", hostname: "bbb", static_config: [
      ip: "192.168.1.100", mask: "255.255.255.0", router: "192.168.1.1"
    ]

    # starting...
    iex> Ethernet.start

Contributing

We appreciate any contribution to Cellulose Projects, so check out our CONTRIBUTING.md guide for more information. We usually keep a list of features and bugs in the issue tracker.