Re: static interface shuts down on disconnect

[Pavel Simerda <psimerda redhat com>]

----- Original Message -----
> From: "Simon Bazley" <simon bazley themartingale com>
> To: "Ritesh Khadgaray" <khadgaray gmail com>
> Cc: "network manager" <networkmanager-list gnome org>
> Sent: Saturday, December 7, 2013 11:01:13 PM
> Subject: Re: static interface shuts down on disconnect
>
> That's not really helpful,

The feature you are requesting has been implemented:

http://cgit.freedesktop.org/NetworkManager/NetworkManager/log/?id=17e91fd46aca2f99f8231d9e9d9916bb110b1be9&qt=grep&q=ignore-carrier

I don't know if it's present in any of the stable updates but it will get to the 0.9.10 release.

> as I need the (database) services on this machine,
> to be used by other machines (so loopback isn't an option), when the cable
> is plugged in.

You aren't the first person to ask for this feature often needed on servers.

> I can understand this being the default behaviour on a desktop,

Yes, it is.

> but this is really not acceptable behaviour on a server

People, please don't repeat this nonsense all over the time. It's perfectly acceptable in many to clear the 
configuration upon cable disconnection. In *some* cases it's unacceptable but that doesn't have much to do 
with the server/desktop/laptop/whatever difference. In this case the "default" behavior will always be a wild 
guess that many will criticise.

You just need to wait for a version of NetworkManager that supports ignore-carrier and set it up to your 
needs without too much rumbling about the defaults.

> (the act of accidentally unpluging a cable kills services that don't need to use the cable).

That indeed suggests your configuration is wrong if your local services rely on addresses assigned to 
external interfaces. I most often solve this by proper network configuration and by only internally using 
addresses assigned to the loopback (or very rarely dummy) interface, whether it's a loopback address or a 
global address assigned to the loopback device.

Next time, when you want to make the address multi-homed, you'll need to do something like that anyway. 

> If there
> really is no way to turn this off, then NetworkManager isn't really suitable
> for servers,

I can't undestand why people all the time assume that their pet peeves or their workarounds to 
misconfiguration of their systems apply to just everyone else out there. You are deploying a bad 
configuration that will bite you sooner or later anyway. You want to turn off carrier detection to work 
around your misconfiguration,
fine.

Actually there are other people who want to use the same technique to work around their own issues, whether 
similar or entirely different. There is demand for such a workaround. It's implemented in NetworkManager git 
master. That's all for now.

> and that seems an unlikely intention.

Just as unlikely as using NetworkManager for servers, until very recently. For 0.9.10, there are many 
features to solve specific needs of huge number of people using NetworkManager on servers, for the not so 
huge number of people using their wifi enabled laptops as experimental servers, and many others. Don't expect 
quirks and workarounds requested by server administrators until then.

Pavel

> Simon
>
> On 07/12/13 11:11, Ritesh Khadgaray wrote:
>
>
>
>
> Hi
>
> On 6 Dec 2013 00:47, "Simon Bazley" < simon bazley themartingale com > wrote:
> > Hi,
> >
> > I've got a server which is running several databases and web services,
> > which is connected to both public and private networks, via different
> > physical network ports.
> >
> > All of the services communicate with each other using the private IP
> > 10.0.0.18 which is bound to the static ip address of the private
> > connection (on eth1). This server is self contained, so the private
> > connection is purely so that other private computers can also access the
> > databases contained on the machine.
> >
> > However, when I physically unplug the cable from the private network eth1
> > goes down, and looses it's IP address, hence all the services on that
> > machine stop being able to communicate with each other.
> >
> > How do I tell NetworkManager, not to shut down that interface on physical
> > disconnect? It should be up, all the time. All physical interfaces on that
> > machine should be up all the time.
> >
> > Simon
> > _______________________________________________
>
> Afaik, this is the expected behaviour. I would suggest your apps to use
> 127.0.0.1 to talk to each other.
>
> Cheers
> T
>
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