Subject: Re: [vserver] Automatic gratuitous ARP on startup
From: Christian Balzer <chibi@gol.com>
Date: Thu, 18 Aug 2011 16:17:52 +0900

On Thu, 18 Aug 2011 00:53:53 -0500 Michael S. Zick wrote:

> On Thu August 18 2011, Christian Balzer wrote:
> > 
> > Hello,
> > 
> > Anyways, I would love to issue a gratuitous ARP (arping) when a vserver
> > comes up, using the normal vserver-util framework. My hope is to find
> > something akin to the "up do-stuff" ability of /etc/network/interfaces
> > control file for ifup/ifdown. 
> >
> 
> Those should be called at the expected times, if that guest context
> has an "init system" that uses them.
> 
I was under the impression that things like the network interfaces and
hostname amongst many others are very much NOT under the control or
influence of the guest. 
Unsurprisingly the interfaces file is empty of any actual contents on my
Debian Squeeze guests. Also, I don't want this done inside the guest if
possible, see below.

> Since each guest has its own "init system", often specified when you
> first build the context, each guest might be running a different sort
> of "init system".  Possibly one without any scripting at all.
> 
> And of course, the host has its own "init system", including scripting
> hooks and scripting which starts the guests.
> 
This is what I am looking for, where are those hooks? Something based on a
config file entry, not hacking any util-vserver scripts. 
The happy flower page gives me no hints to any hooks in the context of
network startup.

> With that in mind, couldn't you just run arp/arping/arpwatch when
> desired in each guest's start-up files as appropriate?  
> Presuming your guests where built to use start-up files.
> 
I'd rather not. Never mind that the guests aren't likely to be uniform
(different distributions/releases), making sure that each guest has such a
startup script installed and that it stays that way in the course of
upgrades or sheer user incompetency is too much of a PITA.

Regards,

Christian
-- 
Christian Balzer        Network/Systems Engineer                
chibi@gol.com   	Global OnLine Japan/Fusion Communications
http://www.gol.com/