Yamaban wrote:
On Thu, 10 Dec 2015 16:00, m.roth@... 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.
My first thought upon reading this was: Well, let's block / drop the irritating packets via firewall / iptables.
Is the source of these packets allowed to contact your box at all?
Yes. Btw, this is a box in a datacenter, hardwired. It's getting its IP, both 4 and 6 via dhcp from another of our servers in that rack.
- No : then block it fully, ipv4 and ipv6
- Yes: block all dhcpv4 / dhcpv6 / radv traffic to and from this source. or even more aggressive: first block this box, second only open the minimum required ports to that box.
IMHO, Networkmanager(and its underlaying helpers) should be much more carefull in handling Router / DHCP stuff. It's biggest niggle for me is a missing white- and black-list for (dis-)allowed routers / dhcp-servers.
Is this the "Right(tm)" thing to do? Dunno, but that would be my gut-telling.
The other admin I work with was working on it, and it seems to be good. However, since he restarted the network, I do find this in the logs: Dec 10 16:06:01 <server> dhclient[96610]: PRC: Renewing lease on ens3f0. Dec 10 16:06:01 <server> dhclient[96610]: XMT: Renew on ens3f0, interval 10900ms. Dec 10 16:06:01 <server> dhclient[96610]: RCV: Reply message on ens3f0 from fe80::: 222:64ff:fef6:d30c. Dec 10 16:06:01 <server> dhclient[96610]: IA_NA status code NoBinding: "Who are you? Do I know you?" Dec 10 16:06:01 <server> dhclient[96610]: XMT: Request on ens3f0, interval 910ms. Dec 10 16:06:01 <server> dhclient[96610]: RCV: Reply message on ens3f0 from fe80:::<addr> Dec 10 16:06:01 <server> dhclient[96610]: IA_NA status code Success: "Assigned fixx ed address." Dec 10 16:06:01 <server> NetworkManager[96668]: <warn> (pid 96610) unhandled DHCP event for interface ens3f0
Oh, yes, not sure who the 222: address is, but the one I've replaced with <addr> is not merely a valid one, it's the server running dibbler.
So, I'm not sure what the "unhandled DHCP event is.
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