# `VintageNetDirect`
[🔗](https://github.com/nerves-networking/vintage_net_direct/blob/v0.10.8/lib/vintage_net_direct.ex#L6)

Support for directly connected Ethernet configurations

Direct Ethernet connections are those where the network connects only two
devices. Examples include a virtual Ethernet interface being run over a USB
cable. This is a popular Nerves configuration for development where the USB
cable provides power and networking to a Raspberry Pi, Beaglebone or other
"USB Gadget"-capable board. Another example would be a direct Ethernet
connection between a device and a development computer.  Such a connection is
handy when a router isn't readily available.

The VintageNet Technology works by assigning a static IP address to the
Ethernet interface on this side of the connection and running a DHCP server
to assign an IP address to the other side of the cable.  IP addresses are
computed based on the hostname and interface name. A /30 subnet is used for
the two IP addresses for each side of the cable to try to avoid conflicts
with IP subnets used on either computer. The DHCP server in use is very
simple and assigns the same IP address every time.

Note that many decisions were made to make this use case work well. If
you're thinking about use cases with more than just the one cable and two
endpoints, you'll want to look elsewhere.

Configurations for this technology are maps with a `:type` field set to
`VintageNetDirect`. `VintageNetDirect`-specific options are in a map under
the `:vintage_net_direct` key (formerly the `:gadget` key). These include:

* `:hostname` - if non-nil, this overrides the hostname used for computing
  a unique IP address for this interface. If unset, `:inet.gethostname/0`
  is used.

Most users should specify the following configuration:

```elixir
%{type: VintageNetDirect}
```

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*Consult [api-reference.md](api-reference.md) for complete listing*