Subject: Re: [vserver] Best way for private networking between guests
From: Fiedler Roman <Roman.Fiedler@ait.ac.at>
Date: Thu, 18 Apr 2013 11:10:42 +0000

 Thu, 18 Apr 2013 11:10:42 +0000
> -----Ursprüngliche Nachricht-----
> Von: Gordan Bobic [mailto:gordan@bobich.net]
> 
> On 18/04/2013 11:15, Laurens Vets wrote:
> > Hello list,
> >
> > I was wondering what the best way is to configure a private network
> > between guests. Would it be best to use a dummy device on the host or
> > just an alias on the loopback interface in the guests?
> 
> Last I tried, loopback comms between the guests didn't work. I'm using a
> dummy interface for private comms between the guests.

I do not use dummy interfaces but combination of loopback and iptables.

The basic idea: the 127/8 is handled differently in the kernel, so I bind 169.254/16
IPs to lo. All internal traffic between guests works fine, just for external traffic,
one has to NAT ext IPs to internals (which is quite OK in our setting since not all
vservers are externally accessible anyhow and different ports on one external IP may
go to different guests.) My flags are "~single_ip,lback_remap"

I tried different approaches before, but that has been the most robust for me so far.

Roman