Having issues with Avast Firewall

[dotmh]

Hi Guys,

I am running an Ubuntu Server 11.04 as a virtual machine on a windows 7 Host.

Because I needed it to have its own IP on my Network , I had to use a Bridged Network connection. This causes me an issue though that my Avast Firewall on my Windows host wont let the virtual instance connect to the internet. I of course need to use the internet to allow me to run everything from basic updates , to adding ruby and install other applications.

I was wondering if anyone knows how to "OK" the virtual machine to connect the internet. I have for the moment disabled the firewall but for security reasons I don't want this to stay like this. I have tried searching Google for a solution but haven't be unable to find a solution.

I would be very grateful for an help and instance , if you guys could just point me in the right direction that would be great.

Kind Regards

[Sasquatch]

When the firewall blocks VB, it should register it in the log. Have you also tried to put VB in the safe applications list, along with the subsequent vboxsvc process?

[dotmh]

Hi,

I have looked through the logs and I can't see anything going from the local IP address of the Virtual Box.

Does anyone know what IP address the firewall will register when using the bridged setting. The server has an IFCONFIG ip address of 198.*.*.8 which is in keeping with what my router is telling me. I have tried allowing all connections from a local network connection but still no result.

I have also allowed Virtual Box to do whatever connection it wants.

Thanks

[BillG]

This sort of problem crops up from time to time and is not easy to fix. In theory the firewall on the host should have no effect on traffic going to or from the guest. The filter driver (which works in conjunction with the NIC driver) separates the traffic at the hardware level using the MAC addresses of the physical and virtual NICs. Traffic addressed to the MAC of the vm's NIC should never be seen by the IP stack in the host OS (and vice versa).

Since it shouldn't happen I can't think of any setting in the firewall which is going to help you. The firewall in the host should not be aware of any traffic going to the guest. It looks like the firewall software is somehow working with the NIC driver to see deeper into the network traffic and is intefering with the filter driver. You would probably need to use a low level network monitor to see what is really happening.

Does the same thing happen with the Windows firewall?

[Sasquatch]

BillG, you got close there. Firewalls these days put a driver on the NIC too, just like VB does. These two can conflict sometimes, causing Bridged to not work or even get installed properly. The firewall might actually drop traffic not destined for the Host that's receiving on the NIC. E.g. it looks for MAC address A that's on the physical NIC, but the VM has MAC address B, it will send that as identifier on the network, which then returns data to that MAC address. The firewall sees a packet destined for the NIC, but not for it's MAC address it is listening on and drops the packet silently.

dotmh:
Take a look at the VirtualBox FAQ, there are some security software noted there that are known to conflict with VB. It's list not complete, there are far too few reports here and we can't test every software and version.

[dotmh]

Hi ,

Cheers for the help, looks like I will have to ether keep the firewall turned off when using my Virtual Server , or change my Firewall software.

I have contacted Avast to see if they know of a solution , though because this is an unusual situation , I don't expect that many of the customers will want to use virtual box with bridged network I am not sure that they will be able to help.

I may just end up waiting for my avast subscription to expire and then by getting a firewall that is more virtual box friendly.

If they do provide me with a solution , I will post it so anyone else that needs it can use it.

[BillG]

You could always install a second NIC in the host and use it exclusively for bridged networking to the guest(s). You could then disable the filter driver (VirtualBox Bridged Networking Driver) on the NIC which your firewall uses.