Packer virtualbox-iso ssh-timeout

packer-vbox-ssh-timeout

$ packer build xxx.json
...
==> virtualbox-iso: Creating virtual machine...
==> virtualbox-iso: Creating hard drive...
==> virtualbox-iso: Creating forwarded port mapping for SSH (host port 4391)
==> virtualbox-iso: Starting the virtual machine...
==> virtualbox-iso: Waiting 10s for boot...
==> virtualbox-iso: Typing the boot command...
==> virtualbox-iso: Waiting for SSH to become available...
==> virtualbox-iso: Timeout waiting for SSH.
==> virtualbox-iso: Unregistering and deleting virtual machine...
==> virtualbox-iso: Deleting output directory...
Build 'virtualbox-iso' errored: Timeout waiting for SSH.