Re: Advanced network configuration

[Ludovic Courtès]

Hi,

Alexey Abramov <levenson@mmer.org> skribis:

>> I would do that by having ‘networking’ depend on ‘firewall’ (say).
>>
>> Does that make sense?
>>
>> It’d be interesting to see whether we need something beyond this.
>
> But what if I just want to stop a firewall? Won't that trigger
> network to restart in that case?

Yes it will, you’re right.

>>> Applications have to be able to gracefully shutdown their network
>>> connections.  Is it the case right now, I don't know?
>>
>> What do you mean?
>
> If you run a simple VM with openssh, login there via ssh client and run
> 'herd power-off root' from the QEMU serial console, the VM will be
> shutdown, but your ssh connection won't know anything about it and the
> socket will be left in a ESTABLISHED state! By typing there system will
> keep trying to send data over there wire (Send-Q).
>
> root@delta ~# ss -ta -A all '( dport = :ssh )' dst 192.168.10.100/24
> Netid             State             Recv-Q             Send-Q                 
>         Local Address:Port                            Peer Address:Port       
>      Process             
> tcp               ESTAB             0                  288                    
>          192.168.10.1:48106                         192.168.10.100:ssh        
>                          
>
> There is no such a problem with shutdown command by the way. 

Hmm I see.

So I guess I don’t know what the correct solution would be, but it’d be
great to see what ideas you have and how systemd approaches these
issues.  Then, if needed, we can adjust the service model in the
Shepherd.

Thanks,
Ludo’.