Subject: Re: [vserver] Network isolation and VServer
From: Jon Bendtsen <jon.bendtsen@laerdal.dk>
Date: Wed, 24 Oct 2007 13:14:36 +0200

On Oct 23, 2007, at 4:46 AM, Daniel Risacher wrote:

> My apologies in advance if this is re-opening old wounds.
>
> I recently set up VServer (mainly so I could run Zimbra w/ less pain)
> and I found that the network isolation did not work the way I
> (perhaps naively?) expected it to.  (Mainly re: binding to TCP ports
> and IPADDR_ANY.)
>
> I write this message to (1) determine whether my understanding of
> VServer's functionality is correct, and possibly (2) suggest potential
> improvements for discussion.
>
> How I think it DOES work
> ------------------------
>
> * Host processes that bind to IPADDR_ANY can recieve connections to  
> any
>   host or guest address

I think that just about the only process the Host system should run is
SSH for remote management. Anything else should be in a vserver
guest.


> * Guest processes that bund to IPADDR_ANY show as having been bound to
>   the guest primary IP address, but can receive connections to the
>   localhost address that come from the same guest.

i dont understand
	"but can receive connections to the
   localhost address that come from the same guest"


> * Bind attempts to IPADDR_ANY from the host will fail if a guest is
>   already listening on that port
>
> * Bind attempts to IPADDR_ANY from a guest will fail if the host is
>   already listening to IPADDR_ANY on that port

The guest will also fail even if it uses it's own ip address and the  
host
has already bound to IPADDR_ANY


> * Connection attempts to "localhost" from a guest can be answered by
>   the host.
>
> How I think it SHOULD work
> --------------------------
>
> I start from the general assumption that a virtual machine should seem
> like an isolated, independent machine as much as possible.  It seems
> to be a desirable goal to minimize the amount of application-level
> configuration tomfoolery that is required.  Based on this...

To my understanding there is a difference between the stable and  
development
series.



JonB