[Lxc-users] veth interface not deleted?

[Jäkel, Guido]

>Quoting Jäkel, Guido (G.Jaekel at dnb.de):
>> Hi,
>>
>> I want to contribute an observation while playing around with my "empty plain vanilla" container template: The test cycle is to start it,
>>open an ssh terminal session to it, leave it idle and regular shut down the container.
>>
>> Now, if the containers eth0 is brought down by the shutdown, after end of the lxc process the corresponding veth is still there and the
>>idle ssh terminal client don't notices anything. This seems to hold for long times (, maybe endless if there is no traffic?). I'm not able to
>>rename the veth at this point; it's said to be busy.
>
>Yes, AIUI this is proper tcp behavior, and there's really nothing we can
>do about it.  The tcp sock has to be kept open so we can tell the other
>end to shutdown.

I completly  agree ... 


>> But if I do a keystroke in the terminal, after some short timeout the client quits with a broken connection message. Also, a short time the veth disappear.
>>
>>
>> By the other hand if I prevent inside the container by configuration that eth0 is driven down, then right at the termination of the lxc
>>process the ssh terminal quits and also, the veth disappears. Beside from the test, I noticed the similar effect on other "in-real-usage"-
>>containers with connection to listeners inside: The veth stays a while until theses inbounding connection have died.

... , but what causes this "helpful" effect? I guess that the open connection are reset, maybe by the stack as a result of closing the network namespace. But why this will happen only if the interface was left up (which is the anormal case)?