[CentOS] CentOS 7, NetworkMangler, and ipv6

[James Hogarth]

On 10 December 2015 at 15:00, <m.roth at 5-cent.us> wrote:

> We've started having a problem with a CentOS 7 server. It looses its IPv6
> address, if I understand this issue correctly. We can get in, if we do ssh
> -4, though.
>
> In the logs, I'm seeing this about twice an hour:
> <warn>  (pid 98466) unhandled DHCP event for interface ens3f0
>
> Now, in googling, I get very few hits putting quotes around "unhanded dhcp
> exception" - in fact, the only one I found that seemed to talk about it
> was from someone's slackware box, where there was some sort of
> configuration, perhaps similar to ifcfg-<if>, and they were telling that
> person to remove it, because it conflicted with what Networkmanager was
> trying to do, leaving it in a confused state.
>
> Any thoughts?
>
>
>

Well there's not much to go on here so you're going to have to provide more
detail ...

Does the system lose all ipv6 connectivity (is the fe80:: address
uncontactable for instance)

Does ip addr sh still show the expected global IPv6 address and it's just
not responding?

Are you using a static ipv6, dhcp ipv6 or SLAAC ipv6 configuration?

Does nmcli c sh <conn-name> still have NM thinking there is an address or
does that show it as gone as well?

Start with those in mind as initial questions for diagnostics...