Re: hubport connectivity problems

[Eric Nichols (DirWiz)]

Many thanks to both for the info and the helpful advice.  On linux both 
solutions worked amazingly well.

I have a few pieces of feedback on the windows version fwiw.

Thomas's solution of using socket worked on windows except the window's 
firewall wanted to build in some exceptions.  The quick fix was to use:
listen=127.0.0.1:1234

lacsaP the mcast stuff on windows errored:
can't bind ip=239.192.168.1 to socket unknown error

I did a bit of googling and found a possible issue with windows and 
mcast: 
https://serverfault.com/questions/1002977/cannot-create-qemu-socket-networking-in-windows-host-using-multicast-fails-with

It would be wonderful to re-imagine hubport as a virtual switch across 
multiple running VM's and handle all this socket/mcast complexity 
internally and away from the OS.  Bonus points if you could merge this 
new idea for hubport with SLIRP!

Many thanks again!
Eric


On 3/28/23 6:05 AM, lacsaP Patatetom wrote:
> Le mar. 28 mars 2023 à 09:36, Thomas Huth <thuth@redhat.com> a écrit :
> > 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
> hi, if you need more than 2 guests, you can start virtual machines
> connected on the same virtual network bus :
>
> qemu \
>    -drive file=hd1.img,media=disk \
>    -nic socket,mac=52:54:00:11:11:11,mcast=239.192.168.1:1101
> qemu \
>    -drive file=hd2.img,media=disk \
>    -nic socket,mac=52:54:00:22:22:22,mcast=239.192.168.1:1101
> qemu \
>    -drive file=hd3.img,media=disk \
>    -nic socket,mac=52:54:00:33:33:33,mcast=239.192.168.1:1101
>
> regards, lacsaP.