# fastd > VPN daemon. > Works on Layer 2 or Layer 3, supports different encryption methods, used by Freifunk. > More information: . - Start fastd with a specific configuration file: `fastd --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 --mode {{tap}} --mtu {{1400}} --config {{path/to/fastd.conf}}` - Validate a configuration file: `fastd --verify-config --config {{path/to/fastd.conf}}` - Generate a new key: `fastd --generate-key` - Show the public key to a private key in a configuration file: `fastd --show-key --config {{path/to/fastd.conf}}` - Show the current version:: `fastd -v`