Re: [Qemu-devel] Making qemu use 10.0.3.x not 10.0.2.x

["andrzej zaborowski" <balrogg@gmail.com>]

On 05/02/2008, Ian Jackson <Ian.Jackson@eu.citrix.com> wrote:
> Andreas Schwab writes ("Re: [Qemu-devel] Making qemu use 10.0.3.x not 10.0.2.x"):
> > Samuel Thibault <samuel.thibault@eu.citrix.com> writes:
> > > Mmm, actually, shouldn't qemu use a more "private" network like a
> > > RFC1918 172.16.0.0/12 network?
> >
> > In which way is 172.16.0.0/12 more "private" than 10.0.0.0/8?
>
> It isn't.  There is no particular reason to choose one rather than
> another so in that sense I disagree with Samuel.
>
> However, there are two things wrong with the current qemu
> arrangements.  The first is that the range isn't configurable without
> recompiling.  I agree with Johannes Schindelin that it should be.
>
> The second is that addresses chosen from RFC1918 space should be
> chosen randomly.  Quoting the RFC:

That would break all the simplicity that user-net brings. If you want
anything more complex, don't use user-net. The idea is that you don't
even have to have dhcp in the guest.

This rfc talks about organisations and networks that are real, not
about the network inside qemu which doesn't have connectivity with
another qemu network. But even on real networks static IPs usually
simplify more than they break. (For example hardware that by default
assumes that 192.168.0.1 is the gateway and if that's the case, works
without configuration).

I don't think an option to change the default 10.0.2.x addresses for
usernet would be of much use either. A person looking up the option in
the manuals can in the same time figure out how to set up non-user-net
networking, or simply recompile. And the person will only look for it
once they find out about the ip collision (most people won't).

Regards