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I'm running Ubuntu 12.04 Server x86. Network connectivity is on eth2 for the host server (the 10ge card). I installed VirtualBox 4.2 using the downloadable deb package from VirtualBox's website. Then I installed phpvirtualbox.

I created a vm with a bridged network card and it can ping out (, I can ping it from my workstation (not the host machine) but it has no http connectivity. When I curl it times out.

We operate a private subnet and a public subnet that go into the same switch. The switch is plugged in to two upstream routers. Both the upstream routers have virtual ips set up as the gateways for these subnets. The routers perform source NAT for the private subnet. The VM host is on the private for security reasons (VPN connection is required for management of the virtual machines).

Should I see a bridge adapter on the host server when the VM starts? I don't see one.

On the host:

swiftfox@xenb:/etc/udev/rules.d$ ip route
default via dev eth2  metric 100 dev eth2  proto kernel  scope link  src

swiftfox@xenb:/etc/udev/rules.d$ sudo iptables -L -nv
Chain INPUT (policy ACCEPT 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination

Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination

Chain OUTPUT (policy ACCEPT 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination

On the guest:

default via dev eth0  metric 100 dev eth0 proto kernel scope link src

No rules in iptables

Here is a tcpdump run on the host server when the guest vm attempts curl

server tcpdump result

share|improve this question
There are different possibilities to connect a VM to the outside world. Which is used determines where to look for the problem. If you don't have any bridges then your VM is probably connected to either a host-only network or a NAT network. But NAT is not possible because you can ping the VM from the outside. So it's probably a Netfilter problem on the host. When you ask networking questions you should always provide the output of ip addr (on host and VM), ip route, and iptables -L -nv. – Hauke Laging May 22 '13 at 2:13
@hauke-laging sorry, I just included that info now. – Sean May 22 '13 at 2:22
You use public IP addresses for a VM behind a private IP LAN? Possible, of course, but strange somehow. No obvious problem. You should look at the traffic (on the host) when you run curl: tcpdump -i eth2 -n host – Hauke Laging May 22 '13 at 2:28
@hauke-laging I added a link to a tcpdump – Sean May 22 '13 at 2:35
That's an unusual problem at any rate. Add the output of tcpdump -i eth0 -n host` on the guest. – Hauke Laging May 22 '13 at 3:08

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