From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1MPuz5-0003gv-60 for qemu-devel@nongnu.org; Sun, 12 Jul 2009 05:04:35 -0400 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1MPuz0-0003TQ-Sm for qemu-devel@nongnu.org; Sun, 12 Jul 2009 05:04:34 -0400 Received: from [199.232.76.173] (port=41234 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1MPuz0-0003Su-Kp for qemu-devel@nongnu.org; Sun, 12 Jul 2009 05:04:30 -0400 Received: from mx2.redhat.com ([66.187.237.31]:44487) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1MPuyz-0004mt-U5 for qemu-devel@nongnu.org; Sun, 12 Jul 2009 05:04:30 -0400 Date: Sun, 12 Jul 2009 10:02:20 +0100 From: "Richard W.M. Jones" Subject: Re: [Qemu-devel] bidirectional data exchange between guest and host without network Message-ID: <20090712090220.GA17003@amd.home.annexia.org> References: <59673.89.3.148.243.1246956346.squirrel@webmail.aql.fr> <20090707090213.GB5690@shareable.org> <53352.89.3.148.243.1246972290.squirrel@webmail.aql.fr> <20090707141204.GL15751@csclub.uwaterloo.ca> <20090707143925.GA14392@shareable.org> <42816.89.3.148.243.1247047400.squirrel@webmail.aql.fr> <20090708135722.GB21508@shareable.org> <42331.89.3.148.243.1247125873.squirrel@webmail.aql.fr> <20090711000400.GG30322@shareable.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090711000400.GG30322@shareable.org> List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Jamie Lokier Cc: Lennart Sorensen , Anthony Lannuzel , qemu-devel@nongnu.org, Paul Brook On Sat, Jul 11, 2009 at 01:04:00AM +0100, Jamie Lokier wrote: > Anthony Lannuzel wrote: > > > Can you not create _another_ network device and use that? > > > QEMU lets you create lots of network devices. > > > > No, I do not want the guest to be able to communicate with the host > > network, so that is not an option. > > So create a network device that is only used for the private > communication, and isolate from the rest of the host network with > firewall rules. > > I'll admit that can be a lot of work, if the host has a complex > network, or a dynamic one where IP addresses are unpredictable. This is precisely the reason why vmchannel is a good thing. There is no IPv4 address you can give to the new interface which won't have the potential to conflict with some other IPv4 address already in use. Extra network devices require special handling in firewall rules and changes to the configuration of every network daemon in the system. If you don't add an extra network device to the guest, then you rely on the host and guest being on the same network, which is not always true. While it's possible to configure the guest specially to avoid this, that doesn't look much like our promise to run any vanilla guest as a virtual machine. Rich. -- Richard Jones, Emerging Technologies, Red Hat http://et.redhat.com/~rjones virt-top is 'top' for virtual machines. Tiny program with many powerful monitoring features, net stats, disk stats, logging, etc. http://et.redhat.com/~rjones/virt-top