[XEN-UBUNTU] Strange behaviour of Virtual Machine bridged network

Hello!

--- System Compositiotn ---
I am running two Virtual Machines over the XEN hypervisor both with Ubuntu Utopic 14.10:

• VM A has an armhf optimized lightweight version of the OS.
• VM B has the Linaro-Developer version. http://releases.linaro.org/15.01/ubuntu/utopic-images/developer/
• The Dom0 has the same configuration of VM B.

--- Problem Description ---
All the machines are connected via a bridged network (xenbr0), held by Dom0. The network seems to work properly, and everything works for Dom0. But when I try to run an apt-get update or a wget //something// on one of the VMs, they fail and get stuck. This is what I got from BOTH the VM:

• apt-get update problem:

• wget problem:

--- Troubleshooting ---
First of all I checked the connectivity on all the machines and the network configuration they have to ensure the correct set up of the bridged network.

• Dom0 etc/network/interfaces

• Dom0 network checking:

Everything seems OK as the bridge exists ad two virtual interfaces are connected to it. On the VMs side I have:

• VMs etc/network/interfaces

Code:

---

# interfaces(5) file used by ifup(8) and ifdown(8)
# Include files from /etc/network/interfaces.d:
source-directory /etc/network/interfaces.d

auto lo
iface lo inet loopback

auto eth0
iface eth0 inet dhcp

---

• VMs network checking:

Code:

---

root@DomU-Ubuntu2:/etc/network# ifconfig
eth0      Link encap:Ethernet  HWaddr 00:16:3e:50:29:c4 
          inet addr:192.168.0.36  Bcast:192.168.0.255  Mask:255.255.255.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:24555 errors:0 dropped:2 overruns:0 frame:0
          TX packets:1392 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:2257768 (2.2 MB)  TX bytes:140028 (140.0 KB)

lo        Link encap:Local Loopback 
          inet addr:127.0.0.1  Mask:255.0.0.0
          UP LOOPBACK RUNNING  MTU:65536  Metric:1
          RX packets:13 errors:0 dropped:0 overruns:0 frame:0
          TX packets:13 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:1232 (1.2 KB)  TX bytes:1232 (1.2 KB)

---

Obviously they differ for MAC and IP address. Anyway, as the network seemed to be up correctly, I tried to ping all the devices in my home LAN from the VMs and Dom0 and everything went good. I than tried to ping the internet (google.com) from the VMs and Dom0 and everything was OK. As the network seemed to work properly I first went to look at the apt sources of the VMs and they only contained:

Code:

---

deb http://ports.ubuntu.com/ubuntu-ports/ utopic main universe
deb-src http://ports.ubuntu.com/ubuntu-ports/ utopic main universe

---

Which are the repos for these kind of distros I am using. Anyway, to try things out I added some of the official repos to the list, by using: http://repogen.simplylinux.ch/

• VMs etc/apt/sources.list

After I changed the list, nothing changed in the command output, so I tried to ping these servers, trying to figure out if I could establish a connection with them. I than used the ping command on ports.ubuntu.com and on it.archive.ubuntu.com, receiving back responses from both of them. So I changed my target and went to check the DNS servers for the VMs. I found these files empty or with the gateway address, so i changed them into:

• VMs etc/resolv.conf
  

by modifying the /etc/resolvconf/resolv.conf.d/base file and cleaning up all the others (tail, head and original) which contained nothing anyway. After this last modification, nothing seems to be changed.

I have not tried any other commands yet, but I suspect that the background problem is related to those I have described above. Now I don't know what I can do more to have things working. Any suggestion would be greatly appreciated!