Lars Noodén via Dng wrote on 12/8/19 9:14 pm:

> On 8/12/19 1:42 PM, Ralph Ronnquist via Dng wrote:
>> Lars Noodén via Dng wrote on 12/8/19 8:07 pm:
>>> [snip]
>>>         -net user,hostfwd=tcp::2222-:22 \
>>>         -net user,hostfwd=tcp::8880-:80 \
>>>         -net user,hostfwd=tcp::4443-:443 \
>>>         -net nic,model=virtio \
>>> [snip]

>>
>> Won't those declaration set up multiple concurrent backends for the
>> single guest NIC ? Shouldn't you rather join up all redirections into a
>> single backend parameter? I can imagine that multple backends could well
>> compete rather than collaborate (though to end up crashing is a bit
>> insensitive). This is of course pure guess work...
>>
>> Ralph.
>
> Thanks. That was it. I am rather sure that invoking it the way shown
> above /used/ to work even if it now causes qemu to crash: Multiple old
> shell scripts I have from 2017 have that style of options, and worked,
> but I'm not sure for which version of qemu they last ran on.
>
> Definitely, putting forwarding all under one option keeps it from
> crashing. The qemu manual page does not warn against using multiple
> "-net user," options though it explicitly says that hostfwd can be used
> multiple times. I guess the right way is now like this:
>

>     -net user,hostfwd=tcp::2222-:22,hostfwd=tcp::8880-:80,...

>
> The behavior has changed. I wonder if this is a bug in qemu?

Well, a slightly irrelevant, and perhaps well known observation: I have
come to think that the most flexible networking for my local VM's is the
"vde mode". It does need a small amount of initial plumbing, with a
(single) supporting tap, and then either a bridge or routing plus local
dhcp. This ends up with a networking "portal" through a (shared) socket
that the qemu processes happily connect to.

With that, I can bring up my VM's willy-nilly, together or in isolation,
all running as non-root user, and presented to the host (and on the
network) as full featured machines without additional sysadmin; just
like "user mode", but without its limitations. And faster, I believe.

Ralph.