Bug 1334050 - Cannot prevent NetworkManager from using DHCPv6
Summary: Cannot prevent NetworkManager from using DHCPv6
Keywords:
Status: CLOSED EOL
Alias: None
Product: Fedora
Classification: Fedora
Component: NetworkManager
Version: 23
Hardware: x86_64
OS: Linux
unspecified
low
Target Milestone: ---
Assignee: Lubomir Rintel
QA Contact: Fedora Extras Quality Assurance
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2016-05-07 16:29 UTC by Frank Ansari
Modified: 2016-12-20 20:23 UTC (History)
6 users (show)

Fixed In Version:
Clone Of:
Environment:
Last Closed: 2016-12-20 20:23:29 UTC
Type: Bug
Embargoed:


Attachments (Terms of Use)
logfile from NetworkManager (3.17 KB, text/plain)
2016-05-07 16:29 UTC, Frank Ansari
no flags Details
ifcfg-enp4s0 (318 bytes, text/plain)
2016-05-07 17:04 UTC, Frank Ansari
no flags Details
logfiile from NetworkManager with debug level (341.18 KB, text/x-vhdl)
2016-05-14 16:31 UTC, Frank Ansari
no flags Details

Description Frank Ansari 2016-05-07 16:29:45 UTC
Created attachment 1154878 [details]
logfile from NetworkManager

Description of problem:
The boot process is delayed by a hanging DHCPv6 transaction.

Version-Release number of selected component (if applicable):
1.0.12

How reproducible:
Booting the PC

Steps to Reproduce:
1.
2.
3.

Actual results:
DHCPv6 request timed out.


Expected results:
NetworkManager should not use DHCPv6 or there should be an option to disable it.


Additional info:
I moved /usr/sbin/dhclient and the boot process worked without delay. IPv6 does not need DHCP.

How can I disable DHCPv6 for a certain interface without removing /usr/sbin/dhclient? Is there a configuration option for NetworkManager or in the dhclient?

Comment 1 Frank Ansari 2016-05-07 17:04:23 UTC
Created attachment 1154879 [details]
ifcfg-enp4s0

Comment 2 Beniamino Galvani 2016-05-12 16:42:16 UTC
(In reply to Frank Ansari from comment #0)
> Expected results:
> NetworkManager should not use DHCPv6 or there should be an option to disable
> it.

Here probably NM is starting DHCPv6 because the router advertisement received from the router says to do so.

How should be IPv6 addresses configured in your network, SLAAC, or DHCPv6?

Can you increase the logging level of NM and attach the logs (actually only the part related to router advertisement is needed).

> Additional info:
> I moved /usr/sbin/dhclient and the boot process worked without delay. IPv6
> does not need DHCP.

This sounds strange, as soon as IPv4 configuration completes, the connection should go up (provided that ipv6.may-fail is set to yes). Indeed, in the attached log the connection is started at 18:16:01 and completes at 18:16:07, without waiting for DHCPv6 to timeout.

Comment 3 Frank Ansari 2016-05-14 16:31:20 UTC
Created attachment 1157507 [details]
logfiile from NetworkManager with debug level

Comment 4 Frank Ansari 2016-05-14 16:41:26 UTC
I use SLAAC. My cable box (CH7485E from Telecolumbus) has a DHCPv6 server which I cannot disable. I have put this to "stateless" now.

Also please note that I have two NICs in my PC. One for IPv4 with static IP and one for IPv6 with SLAAC.

Also I have removed everything from /var/lib/NetworkManager and disbled firewalld for testing.

But the problem still remains. I always get this timeout.

Comment 5 Beniamino Galvani 2016-05-20 15:58:20 UTC
 May 14 18:04:40 : XMT: Info-Request on enp4s0, interval 27840ms.
 May 14 18:04:40 : RCV: Reply message on enp4s0 from fe80::de53:7cff:feae:157.
 May 14 18:04:40 : Response without a server identifier received.
 May 14 18:04:40 : Invalid Reply - rejecting.

The DHCPv6 server is broken and sends a Reply message without the Server Identifier option. This is not compliant to RFC 3315:

   The server MUST include a Server Identifier option containing the
   server's DUID and the Client Identifier option from the Request
   message in the Reply message.

If the router advertisement messages tell NM to use DHCPv6, NM will do it and I'm not aware of ways to disable this behavior. But I think this is really an issue that should be fixed on the router side.

Comment 6 Frank Ansari 2016-05-21 10:35:17 UTC
In this case I see no possibilty to fix it for me. I cannot change the firmware of the CH7485E cable box.

Comment 7 Fedora End Of Life 2016-11-25 08:58:17 UTC
This message is a reminder that Fedora 23 is nearing its end of life.
Approximately 4 (four) weeks from now Fedora will stop maintaining
and issuing updates for Fedora 23. It is Fedora's policy to close all
bug reports from releases that are no longer maintained. At that time
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Comment 8 Fedora End Of Life 2016-12-20 20:23:29 UTC
Fedora 23 changed to end-of-life (EOL) status on 2016-12-20. Fedora 23 is
no longer maintained, which means that it will not receive any further
security or bug fix updates. As a result we are closing this bug.

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