RE: Need to send the dhclient6 to background in Centos 8

[Jorge Perez Higuera <joperez arsys es>]

So that is not working here. The machine gets the Ipv4 address quickly and the dhclient ipv6 process starts 
getting an ip. 30 seconds later the NetworkManager-wait-online service waits until it fails. 
If I create an ipv6 reservation in the dhcp server the machine boots good with bot ipv4 and ipv6 addresses

The network setup is correct in this environment:
NAME="whatever"
TYPE=Ethernet
DEVICE=<interface>
ONBOOT=yes
BOOTPROTO=dhcp
IPV6INIT=yes
IPV6_AUTOCONF=no
IPV6_FAILURE_FATAL=no  (inverse "may fail" meaning)
DHCPV6C=yes
DHCPV6_DUID=ll


-----Mensaje original-----
De: Thomas Haller [mailto:thaller redhat com] 
Enviado el: martes, 8 de octubre de 2019 18:05
Para: Jorge Perez Higuera; networkmanager-list gnome org
Asunto: Re: Need to send the dhclient6 to background in Centos 8

On Tue, 2019-10-08 at 15:10 +0000, Jorge Perez Higuera via networkmanager-list wrote:
> If the dhcp server does not send an ipv6 lease IP, dhclient ipv6 
> process tries to get that ip during 30 seconds. That causes (i can see 
> that via systemd-analyze blame) the startup of the  
> NetworkManager-wait-online service is delayed, delaying the 
> network-online.target I have services depending of this target and 
> that delay causes some troubles to me.

Hi,


DHCPv6 is only done if either

- "ipv6.method=dhcp" is configured in the profile

- "ipv6.method=auto" is configured in the profile, and the IPv6 router in your network sets the managed flag 
in its router advertisements, to indicate to use DHCPv6.


It seems better to fix your configuration and/or networking setup.

Also, if you configure ipv6.may-fail=yes and the device gets a IPv4 address, then the entire device is 
considered active (and no longer blocks NetworkManager-wait-online). So, if you care about IPv6, you maybe 
want to set ipv6.may-fail=no.


best,
Thomas


> -----Mensaje original-----
> De: Thomas Haller [mailto:thaller redhat com] Enviado el: martes, 8 de 
> octubre de 2019 14:00
> Para: Jorge Perez Higuera; networkmanager-list gnome org
> Asunto: Re: Need to send the dhclient6 to background in Centos 8
>
> On Tue, 2019-10-08 at 11:37 +0000, Jorge Perez Higuera via 
> networkmanager-list wrote:
> > Hi all. I need some help
> >  
> > I need to send the dhclient ipv6 process to background (I use
> > dhcp=dhclient)
> > I know it can be done passing the –nw parameter via dhclient but i 
> > don’t know how to pass this to dhclient via NetworkManager Also in 
> > Centos 8 it start in foreground (-d parameter)
> >  
> > Is there any way to do this?
> > Is is posible via internal client?
> >  
> > NetworkManager 1.14.0
> > Centos 8
> >  
> > Thank you
>
> Hi,
>
> when NetworkManager uses dhclient as its DHCP plugin, then the process 
> is controlled by NetworkManager. In that case, NetworkManager will 
> always spawn the process in the background. That is regardless whether 
> NetworkManager itself is in the background or not). Anyway, the way 
> NetworkManager spawns this process is of little concern to the user.
>
> In fact, when using NetworkManager you usually would be not concerned 
> with dhclient at all. The process is for the most part an 
> implementation detail of how NetworkManager does DHCP.
>
> Which problem are you trying to solve?
>
> best,
> Thomas
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