Added * New API action: SendCtrlAltDel, used to initiate a graceful shutdown, if the guest has driver support for i8042 and AT Keyboard. See [the docs](docs/api_requests/actions.md#sendctrlaltdel) for details. * New metric counting the number of egress packets with a spoofed MAC: `net.tx_spoofed_mac_count`. * New API call: `PATCH /network-interfaces/`, used to update the rate limiters on a network interface, after the start of a microVM. Changed * Added missing `vmm_version` field to the InstanceInfo API swagger definition, and marked several other mandatory fields as such. * New default command line for guest kernel: `reboot=k panic=1 pci=off nomodules 8250.nr_uarts=0 i8042.noaux i8042.nomux i8042.nopnp i8042.dumbkbd`. Fixed * virtio-blk: VIRTIO_BLK_T_FLUSH now working as expected. * Vsock devices can be attached when starting Firecracker using the jailer. * Vsock devices work properly when seccomp filtering is enabled.