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Subject: Re: [Qemu-devel] about DHCP server in qemu
From: "John R. Hogerhuis" <jhoger@pobox.com>
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Date: Fri, 30 Sep 2005 11:28:53 -0700
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To: qemu-devel@nongnu.org

On Fri, 2005-09-30 at 09:10 -0400, Jim C. Brown wrote:
> On Fri, Sep 30, 2005 at 10:17:04AM +0200, octane indice wrote:
> > > 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.
> > > 
> > it would be good to get that working :)
> > 
> 
> Alas, that is so difficult it is nearly impossible.
> 

Nearly? Oh come on... you know it ain't possible, period.

Ping (ICMP) operates at the IP level. An unprivileged socket, which is
what user-net (slirp) uses can only send/receive packets at the ported
protocols level, which means UDP or TCP.

Of course, why ping? If all you need to do is validate connectivity,
find some ported protocol service to connect to in order to validate
connectivity.

If non-ported protocols like ICMP must be supported use tun/tap.

-- John.