Não é possível fazer solicitações HTTP de saída da VM vagante

Não consigo me conectar à Internet a partir de uma máquina virtual Vagrant que eu configurei.

Por exemplo, na raiz, quando digito:

curl http://google.com

Falha com a mensagem:

curl: (6) Couldn't resolve host 'google.com'

Não tenho certeza se é uma configuração de firewall, embora, tanto quanto eu saiba, não criei nenhuma regra de firewall para a porta 80 ou qualquer outra porta.

Aqui está a seção relevante do meu arquivo Vagrant. Se houver outras informações que eu possa fornecer, entre em contato nos comentários:

Vagrant.configure("2") do |config|
  # All Vagrant configuration is done here. The most common configuration
  # options are documented and commented below. For a complete reference,
  # please see the online documentation at vagrantup.com.


  # Let Vagrant manage the hostname at boot
  config.vm.hostname = "devbox"

  # Create a forwarded port mapping which allows access to a specific port
  # within the machine from a port on the host machine. In the example below,
  # accessing "localhost:8080" will access port 80 on the guest machine.
  # config.vm.network :forwarded_port, guest: 80, host: 8080

  # Create a private network, which allows host-only access to the machine
  # using a specific IP.
  config.vm.network :private_network, ip: "10.0.0.10"

  # Create a public network, which generally matched to bridged network.
  # Bridged networks make the machine appear as another physical device on
  # your network.
  # config.vm.network :public_network

  # Create a public network with a given hardware address.  You can
  # configure your DHCP server (on your router) to assign a particular IP
  # address to the VM.  Update your hosts file accordingly.
  # config.vm.network :public_network, mac: "0a00251010101"

  # Share an additional folder to the guest VM. The first argument is
  # the path on the host to the actual folder. The second argument is
  # the path on the guest to mount the folder. And the optional third
  # argument is a set of non-required options.
  #config.vm.synced_folder "vagrant/logs", "/logs",
  #  owner: "root", group: "root"

  # Base box to use with Virtualbox provider
  config.vm.box = "debian-7.0.0-amd64-base"
  config.vm.box_url = "http:/mysite.com/debian-7.0.0-amd64-base.box"