From: Herbert Poetzl (herbert_at_13thfloor.at)
Date: Fri 24 Sep 2004 - 17:17:42 BST
On Fri, Sep 24, 2004 at 05:18:19PM +0200, Gilles wrote:
> > > E.g. I was wondering whether it is possible to simulate several subnets
> > > inside a single host (i.e. without resorting to a second nic!).
> > you do not need a separate nic to have a subnet on a
> > linux host,
> Several *different* subnets?
> How? To make things clearer, suppose that there is one subnet,
> partly physical, partly virtual (maybe this is not the right word),
> as follows:
> H1 (border firewall) has 2 nics:
> - 192.168.1.0 <---> (via dynamic IP/pppd) Internet
> - 192.168.2.20 <---> H2
> H2 (services) has 1 nic:
> - 192.168.2.10
> On H2:
> - vserver (apache): 192.168.2.55
> Can I create a second purely virtual net inside H2, say 192.168.3.0 ?
> [Where I would put e.g. a "mysql" vserver, with address 192.168.3.55.]
if you do not accept/route packets for the 192.168.3.0/24
you can assign those IPs to for example the dummy0 interface
(what interface doesn't matter actually) and use it on
the host only ...
> > but all communication on the same host
> > will happen via lo (see More Documentation on the
> > linux-vserver wiki), so you have to keep that in mind.
> Is it on
> Which document?
> > > If I remember correctly, "vmware" does that (as was already
> > > pointed out by someone else).
> > > So the question is: How to do it with vserver?
> > vmware and QEMU or Bochs use a separate kernel (similar
> > to that what UML does) and communicate via tun/tap
> > devices with the host, which adds some overhead but
> > provides separated 'interfaces' on the host ...
> Is it possible to have the same kind of communication between
possible yes, implemented no, because it doesn't
make much sense to feed network data through some
userspace pipe ...
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