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Re: KVM network weirdness

On 2018-10-11 01:12 AM, Gary Dale wrote:
I'm running an AMD64 server using Debian/Stretch.

I've just created a new Windows 7 VM using the Virtual Machine Manager GUI, starting with 2 IDE CD-ROMs so that I could install with virtio disk drivers for the qcow2 image.

The install went smoothly but when it finished, it didn't have network connectivity. I replaced the NIC with a virtio driver (it had been RealTek 8139) but that didn't help. The problem was that it wasn't getting a DHCP address from my router.

I logged into my router and noted that the router had a connection to it but showed it as self-assigned - one of the 169. addresses that Windows uses when it can't get one from DHCP. When I manually set the address, it also shows on the router but this time I get network access. I was able to activate windows and download almost 200 updates.

What I can't do is connect to the domain. I have Samba 4 running on the same server as the VMs. I have 3 other Windows VMs (XP, XP64 and Windows 10) running on the same server and they have all joined the domain (years ago). but for some reason I can't get this one to join. Windows can't contact the domain.

In the network setup, I did add the WINS server's IP address in the advanced settings. That didn't help.

My other virtual machines use all use DHCP, but as I mentioned, it doesn't seem to want to work on this one.

I also recently set up a real Windows 7 machine and added it to a different Samb4 domain without any problems (once I got the network driver working). And I recently re-added to other machines (one virtual, one real) to the that same network. I did notice that Windows seems to prefer DHCP reservation over static addresses in that domain, so perhaps I'm missing a network setting.

Any ideas?

Further to above, I have been looking at my hypervisor's networking. My Windows 10 VM, for example, uses DHCP to get its IP address. This works fine. However the same setup doesn't work on my Windows 7 VM. Both NICs are linked to br0.

When I check my hypervisor's configuration, I see my physical NIC and br0 as expected but I also see virbr0 which is on a different subnet (IP address I note this is supposed to be normal - something to do with how virt-manager handles the guest's networking.

I therefore changed my hypervisor's networking to dhcp reservation and removed the manual bridging (br0). After also changing the VM NICs to use virbr0 instead of br0, I was able to get the Windows 7 VM to use DHCP. All the Windows VMs now get addresses in the 192.168.122.x range. They have both Internet access and access to samba shares on the hvpervisor.

Since I can't log in with a domain account, I have to connect to network shares using "different credentials" in the form <domain name>\<domain user name>. This works, which indicates the domain controller is reachable.

However I am still unable to join the VM to the domain. When I go through the Windows "join a domain" process, I get an "An Active Directory Domain Controller (AD DC) for the domain ... cannot be contacted" error.

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