.. zephyr:code-sample:: eth-native-posix
   :name: Native POSIX Ethernet
   :relevant-api: net_core ethernet

   Create a network interface to the host system.

Overview
********

The eth_native_posix sample application for Zephyr creates a **zeth** network
interface to the host system. One can communicate with Zephyr via this network
interface.

The source code for this sample application can be found at:
:zephyr_file:`samples/net/eth_native_posix`.

Building And Running
********************

To build the eth_native_posix sample application, follow the steps
below.

.. zephyr-app-commands::
   :zephyr-app: samples/net/eth_native_posix
   :host-os: unix
   :board: native_posix
   :conf: <config file to use>
   :goals: build
   :compact:

Normally one needs extra privileges to create and configure the TAP device in
the host system. If the user has set the
:kconfig:option:`CONFIG_ETH_NATIVE_POSIX_STARTUP_AUTOMATIC` option (this is disabled
by default), then the user needs to use ``sudo`` to execute the Zephyr process
with admin privileges, like this:

.. code-block:: console

    sudo --preserve-env=ZEPHYR_BASE make -Cbuild run

If the ``sudo --preserve-env=ZEPHYR_BASE`` gives an error,
just use ``sudo --preserve-env`` instead.

If the :kconfig:option:`CONFIG_ETH_NATIVE_POSIX_STARTUP_AUTOMATIC` option
is not enabled (this is the default), then the user should
execute the ``net-setup.sh`` script from Zephyr `net-tools`_ repository.
The script should be run before executing the Zephyr process. The script
will create the zeth interface and set up IP addresses and routes.
While running ``net-setup.sh`` requires root access, afterwards Zephyr
process can be run as a non-root user.

You can run the ``net-setup.sh`` script like this::

   cd net-tools
   sudo ./net-setup.sh

or::

   sudo ./net-setup.sh --config ./zeth-vlan.conf

See also other command line options by typing ``net-setup.sh --help``.

When the network interface is set up manually, you can leave the wireshark
to monitor the interface, and then start and stop the zephyr process without
stopping the wireshark.

Setting things manually works the same as working with SLIP connectivity
in QEMU.

If you want to connect two Zephyr instances together, you can do it like this:

Create two Zephyr config files prj1.conf and prj2.conf. You can use
:zephyr_file:`samples/net/eth_native_posix/prj.conf` as a base.

Set prj1.conf IP address configuration like this:

.. code-block:: console

    CONFIG_NET_CONFIG_MY_IPV6_ADDR="2001:db8:100::1"
    CONFIG_NET_CONFIG_PEER_IPV6_ADDR="2001:db8:100::2"
    CONFIG_NET_CONFIG_MY_IPV4_ADDR="198.51.100.1"
    CONFIG_NET_CONFIG_PEER_IPV4_ADDR="198.51.100.2"
    CONFIG_NET_CONFIG_MY_IPV4_GW="203.0.113.1"
    CONFIG_ETH_NATIVE_POSIX_RANDOM_MAC=n
    CONFIG_ETH_NATIVE_POSIX_MAC_ADDR="00:00:5e:00:53:64"
    CONFIG_ETH_NATIVE_POSIX_SETUP_SCRIPT="echo"
    CONFIG_ETH_NATIVE_POSIX_DRV_NAME="zeth.1"

Set prj2.conf IP address configuration like this:

.. code-block:: console

    CONFIG_NET_CONFIG_MY_IPV6_ADDR="2001:db8:200::1"
    CONFIG_NET_CONFIG_PEER_IPV6_ADDR="2001:db8:200::2"
    CONFIG_NET_CONFIG_MY_IPV4_ADDR="203.0.113.1"
    CONFIG_NET_CONFIG_PEER_IPV4_ADDR="203.0.113.2"
    CONFIG_NET_CONFIG_MY_IPV4_GW="198.51.100.1"
    CONFIG_ETH_NATIVE_POSIX_RANDOM_MAC=n
    CONFIG_ETH_NATIVE_POSIX_MAC_ADDR="00:00:5e:00:53:c8"
    CONFIG_ETH_NATIVE_POSIX_SETUP_SCRIPT="echo"
    CONFIG_ETH_NATIVE_POSIX_DRV_NAME="zeth.2"

Then compile and run two Zephyr instances
(if ``sudo --preserve-env=ZEPHYR_BASE`` gives an error,
just use ``sudo --preserve-env`` instead):

.. code-block:: console

    cmake -DCONF_FILE=prj1.conf -DBOARD=native_posix -Bbuild1/native_posix .
    make -s -C build1/native_posix
    sudo --preserve-env=ZEPHYR_BASE make -s -C build1/native_posix run

.. code-block:: console

    cmake -DCONF_FILE=prj2.conf -DBOARD=native_posix -Bbuild2/native_posix .
    make -s -C build2/native_posix
    sudo --preserve-env=ZEPHYR_BASE make -s -C build2/native_posix run

Bridge the two Zephyr instances together:

.. code-block:: console

    sudo brctl addbr zeth-br
    sudo brctl addif zeth-br zeth.1
    sudo brctl addif zeth-br zeth.2
    sudo ifconfig zeth-br up

After this, you are able to ping device 1 from device 2 in net-shell:

.. code-block:: console

    # In device 1
    net ping 2001:db8:200::1
    net ping 203.0.113.1

.. code-block:: console

    # In device 2
    net ping 2001:db8:100::1
    net ping 198.51.100.1

Note that in this setup you cannot access these two Zephyr devices from
your host. If you want to do that, then you could create a new network
interface with proper IP addresses and add that interface to the Zephyr
bridge.

.. _`net-tools`: https://github.com/zephyrproject-rtos/net-tools