# fastd > VPN daemon. > Works on Layer 2 or Layer 3, supports different encryption methods, used by Freifunk. > See also: `ivpn`, `mozillavpn`, `mullvad`, `warp-cli`. > More information: . - Start `fastd` with a specific configuration file: `fastd {{[-c|--config]}} {{path/to/fastd.conf}}` - Start a Layer 3 VPN with an MTU of 1400, loading the rest of the configuration parameters from a file: `fastd {{[-m|--mode]}} {{tap}} {{[-M|--mtu]}} {{1400}} {{[-c|--config]}} {{path/to/fastd.conf}}` - Validate a configuration file: `fastd --verify-config {{[-c|--config]}} {{path/to/fastd.conf}}` - Generate a new keypair: `fastd --generate-key` - Show the public key to a private key in a configuration file: `fastd --show-key {{[-c|--config]}} {{path/to/fastd.conf}}` - Show the current version: `fastd {{[-v|--version]}}`