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I have a Vagrant-provisioned CentOS guest on an Ubuntu host. Internet access from host is absolutely fine. But Internet access from guest often fails unless host is using VPN.

For example:

Host using standard network adapter, no VPN:

$ curl
curl: (6) Couldn't resolve host ''

Host using VPN:

$ curl
{ successful-json-payload }

Guest networking is NAT. VirtualBox GUI showing the correct host adapter.

I live in Thailand and VPN is US-based. Ideas?

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The error is telling you that DNS is not working. What name servers have you set in the guest, and can you ping them? – Paul Feb 17 '13 at 13:03
@Paul: Using Google DNS: and Yep, can ping them from the guest. But attempting to curl (from the guest) the standard assortment of reliable sites fails with curl: (6) Couldn't resolve host. And still, if I connect the host to my VPN, those curls all sail through smoothly. – David Weinraub Feb 17 '13 at 16:03
Strange, the dns must be getting bloked, or failing to NAT. Your question says "often fails", does that means it works without VPN sometimes? How about doing a tcpdump host <guest ip> and port 53 on the host to see if the DNS queries are making it out ok. – Paul Feb 17 '13 at 21:07
What happens if you do a "traceroute -n" ? This will tell us if you have a problem with outbound Internet connectivity or the DNS service. – davidgo Feb 17 '13 at 22:01
traceroute -n runs clean to completion. But traceroute to another ping-able (!) IP dies. @Paul: IP of guest is Ping from host to guest fails. tcpdump on host as suggested fails ("no suitable device found"). Thanks for all the ideas. Keep 'em coming! ;-) – David Weinraub Feb 18 '13 at 5:31

You might want to configure your vagrant according to the snippet below, might have something to do with it. It was driving me nuts too! do |config|
  # ...

  config.vm.customize ["modifyvm", :id, "--natdnshostresolver1", "on"]

source :

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That looks like an interesting idea. I'll try it out and get back to you. Thanks! ;-) – David Weinraub Mar 21 '13 at 9:33

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