Multiple NAT router

[Marko Zec]

On Monday 24 July 2006 11:09, Brian Candler wrote:
> On Fri, Jul 21, 2006 at 11:13:47AM -0600, Brett Glass wrote:
> > I have an application in which I'd like a FreeBSD router to have
> > multiple, isolated LANS attached to it, each with the same address
> > space. The FreeBSD box would take the place of multiple NAT routers.
> >
> > For example, I might want to have three internal Ethernet
> > interfaces on the FreeBSD box. Each would be connected to a LAN
> > whose internal addresses are 192.168.0.0/24. The FreeBSD box would
> > do NAT for all of them, and of course they could not "see" one another.
>
> FreeBSD won't support this 'out of the box' - because of the problem that
> you identified of having multiple NICs all with the same address range
> assigned to them.
>
> There's a project called 'vimage' which adds a separate virtual forwarding
> table per jail. This might work for you, although all the natd's "outside"
> interfaces would need to sit on the same interface, and I don't know if it
> can do that.

Yes this should work with a virtualized stack - all the "outsied" interfaces 
in each jail / virtual stack could be simply bridged together using netgraph 
which is virtualization-agnostic, i.e. a global facility in the current 
implementation of "vimage".

Of course a significant problem might be that the stack virtualization patches 
exist only for FreeBSD 4.x, but there's a very good chance that a formal 
project aimed at bringing vimage into sync with 6.x and -CURRENT could start 
shortly...

Cheers,

Marko


> Otherwise - you can run multiple instances of FreeBSD under a virtual
> machine environment like Xen or VMware, and bridge all the 'outside'
> interfaces together onto the same NIC.
>
> Also - you may still end up with a separate outside IP per vimage or VM, so
> maybe then you need another NAT instance to NAT all of those onto a single
> IP address :-)
>
> Regards,
>
> Brian.
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