docs/get-started/set_up_femu.md

# Set up the Fuchsia emulator (FEMU)

This document describes how to set up the Fuchsia emulator (FEMU).

## Prerequisites

To run FEMU, you must have

 * [Fuchsia source installed and environment variables created](/docs/get-started/get_fuchsia_source.md)
 * [Configured and built Fuchsia](/docs/get-started/build_fuchsia.md)

Note: When you configure Fuchsia for an emulator, use the `fx set`
command to set an emulator-specific board, either `qemu-x64` or `qemu-arm`.

## Configure network

For Fuchsia's ephemeral software to work with FEMU, you need to configure
an IPv6 network.

  * [Linux configuration](#linux-config)
  * [macOS configuration](#mac-config)

### Linux {#linux-config}

To enable networking in FEMU, run the following commands:

```sh
sudo ip tuntap add dev qemu mode tap user $USER
sudo ip link set qemu up
```

### macOS {#mac-config}

You need to install
[TunTap](http://tuntaposx.sourceforge.net/index.xhtml){:.external}, kernel
extensions that allow macOS to create virtual network interfaces.

To install TunTap on macOS:

1.  Install [Homebrew](https://brew.sh){:.external}:

    ```posix-terminal
    /bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"
    ```

1.  Install TunTap:

    ```posix-terminal
    brew cask install tuntap
    ```

The installation of TunTap may fail at first. In that case, do the following:

1.  Open `System Preferences`.
1.  Open `Security & Privacy` and select the`General` tab.
1.  Next to the `System software from developer "Mattias Nissler" was blocked
    from loading.` message, click **Allow** (see Apple's
    [User-Approved Kernel Extension Loading](https://developer.apple.com/library/archive/technotes/tn2459/_index.html){:.external}
    for details).
1.  Run the install command again:

    ```posix-terminal
    brew cask install tuntap
    ```

After installing TunTap, run the following command:

```posix-terminal
sudo chown $USER /dev/tap0
```

## Start FEMU

The most common way to run FEMU is with networking enabled, using the following command:

```posix-terminal
fx emu -N
```

Once you run the command, a separate window opens with the title "Android Emulator" where you
can run shell commands on your Fuchsia emulator, just like you would on a Fuchsia device.

Note: If you don't have access to the GUI in Linux, you will get an error and a suggestion to
run the emulator using `xvfb-run`. `xvfb-run fx emu` loads FEMU using a virtual framebuffer
and allows FEMU to work without a GUI. 

Note: If you need to reach the internet from FEMU, configure IP
forwarding and IPv4 support on the emulator TAP interface.

## Next steps

 *  For more options on running FEMU, see [Running the Fuchsia Emulator](/docs/development/run/femu.md).
 *  To learn more about how FEMU works, see the
    [Fuchsia emulator (FEMU) overview](/docs/concepts/emulator/index.md).
 *  To learn more about Fucshia device commands and Fuchsia workflows, see
    [Explore Fuchsia](/docs/get-started/explore_fuchsia.md).