To make an SSH connection to a Fuchsia device, some ffx commands (such as ffx target show and ffx log) require Fuchsia-specific SSH keys to be present on the host machine.
Note: With the version 9.20220727.0.1 or higher, some ffx commands (such as ffx target flash and ffx emu start) will automatically generate Fuchsia-specific SSH keys on the host machine if they are not found in the $HOME/.ssh directory. (To check the ffx version on your host machine, run ffx sdk version.)
During development, one or more public SSH keys (listed in fuchsia_authorized_keys) are loaded to a Fuchsia device, typically when a new Fuchsia image is flashed to the device. Once the device is loaded with these public SSH keys, the ffx commands (running from the host machine where a matching private SSH key is stored) can establish an SSH connection to the device.
By default, Fuchsia-specific SSH keys are stored in the $HOME/.ssh directory of the host machine, as shown below:
$HOME/.ssh/fuchsia_ed25519 $HOME/.ssh/fuchsia_authorized_keys
These files are created by ffx if they do not exist.
Note: These keys are not password protected. Don't use these keys for non-development devices.
These files contain the following:
fuchsia_ed25519: A private SSH key. The content of this file must not be revealed or shared.fuchsia_authorized_keys: A list of one or more authorized public SSH keys.The fuchsia_authorized_keys file must include the public SSH key for fuchsia_ed25519. During the flashing process, the fuchsia_authorized_keys file gets uploaded from the host machine to the Fuchsia device.
If you have multiple development machines, it's recommended that the Fuchsia SSH keys are synchronized across your development machines. This may require you to copy the existing Fuchsia SSH keys files from one machine to another.