Re: hubport connectivity problems

[Thomas Huth]

On 27/03/2023 21.52, Eric Nichols (DirWiz) via wrote:
> Long time user, first time poster...
>
> My setup is simple.  Debian host running qemu 7.2.0 and 2 guest (Windows 
> 2010 workstation & 2022 server).  My goal is to setup a private guest only 
> network (no connection to host) with hubport.
>
> Based on the docs I've tried:
> -netdev hubport,hubid=0,id=hub0 -device virtio-net-pci,netdev=hub0
>
> There is also the second option of:
> -nic hubport,hubid=0,model=virtio-net-pci
>
> And also small mention that a hubport 0 will be setup if you just use a 
> virtual adapter and don't connect it to anything:
> -net nic,model=virtio-net-pci,macaddr=52:54:00:00:00:03
>
> I did static IPs on both of the guests but can't ping or connect over TCP.
> Any ideas?

hubport basically emulates a hub *within* one instance of QEMU. Hubport 
alone does not connect to any other QEMU (i.e. guest) instance. It's mostly 
a legacy concept from the early days of QEMU - and unless you want to 
connect multiple NICs of one guest together, you likely don't need it. (see 
also https://www.qemu.org/2018/05/31/nic-parameter/ for some more information).

If you want to connect two local guests via a local network, you could have 
a look at the "-netdev socket" option. For example, start one QEMU with 
"-nic socket,model=virtio-net-pci,id=net0,listen=:1234" and the other QEMU 
with "-nic socket,model=virtio-net-pci,id=net1,connect=:1234" and you should 
be able to see the network traffic of one guest on the interface of the 
other and vice versa.

 HTH,
  Thomas