smartos_base64_191.json

{
  "brand": "joyent",
  "image_uuid": "cf7e2f40-9276-11e2-af9a-0bad2233fb0b",
  "max_physical_memory": 512,
  "quota": 20,
  "nics": [
    {
      "nic_tag": "admin",
      "ip": "dhcp",
      "primary": true
    }
  ]
}

Note that if you are using VirtualBox, you need to set your interface for the SmartOS global zone to both Bridged and Promiscuous (Allow All) modes.

On Mac OS, this works for wired interfaces, but not wireless...(ﾉಥ益ಥ）ﾉ ┻━┻