Re: [Qemu-devel] about DHCP server in qemu

[Jim C. Brown]

On Fri, Sep 30, 2005 at 01:50:47AM +0400, Brad Campbell wrote:
> >No. In fact, the server is set up to always return the same IP in response 
> >to
> >a request.
> err.. it works for me...

Yes, it seems that Fabrice has slipped in a few changes since I last looked at
the slirp code. :) The internal DHCP server can now support 16 dhcp clients.
That's for multiple clients within a single qemu guest though (think multiple
NICs here). I don't see any way for qemu guests to be able to ping each other
(for example) if they are both using user-net.

> Even if it worked like a full fledged DHCP server, there's no 
> >way to
> >connect multiple guests together. The best you can do is slirpvde.
> >
> This gives me 9 qemu sessions that all get different 10.x.x.x ip addresses 
> via dhcp
> 
> #!/bin/sh
> rm /tmp/qemu-irc-*
> for i in 1 2 3 4 5 6 7 8 9 ; do
> qemu-img create -b /tracks/lin.img -f qcow /tmp/qemu-irc-$i
> qemu -fda /tracks/floppy.img -hda /tmp/qemu-irc-$i -boot a -user-net 
> -macaddr C0:0F:FE:01:01:9$i -m32 &
> done
> 
> Regards,
> Brad

I find it suprising that this works. From the code in slirp/bootp.c it looks
like qemu's dhcp server will give out 10.0.2.15 first, then 10.0.2.16, and so
on (so it goes in sequential order). But thats within a single qemu session.
Theres no way for multiple user-net qemu guests to communicate (at least on
the ethernet level) so the guests should have the same ip address. Very strange.

-- 
Infinite complexity begets infinite beauty.
Infinite precision begets infinite perfection.