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Native Posix Ethernet


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: samples/net/eth_native_posix.

Building And Running

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

west build -b native_posix samples/net/eth_native_posix -- -DCONF_FILE=<config file to use>

Normally one needs extra privileges to create and configure the TAP device in the host system. If the user has set the :kconfig:`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:

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:`CONFIG_ETH_NATIVE_POSIX_STARTUP_AUTOMATIC` option is not enabled (this is the default), then the user should execute the 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 requires root access, afterwards Zephyr process can be run as a non-root user.

You can run the script like this:

cd net-tools
sudo ./


sudo ./ --config ./zeth-vlan.conf

See also other command line options by typing --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 samples/net/eth_native_posix/prj.conf as a base.

Set prj1.conf IP address configuration like this:


Set prj2.conf IP address configuration like this:


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

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
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:

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:

# In device 1
net ping 2001:db8:200::1
net ping
# In device 2
net ping 2001:db8:100::1
net ping

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.