Report information
The Basics
Id:
47957
Status:
open
Priority:
Medium/Medium
Queue:
dhcp-public
People
Owner:
Nobody in particular
Requestors:
Marc Dionne <marc.dionne@auristor.com>
Cc:
AdminCc:
BugTracker
Version Fixed:
(no value)
Version Found:
(no value)
Versions Affected:
(no value)
Versions Planned:
4.4.2
Priority:
(no value)
Severity:
(no value)
CVSS Score:
(no value)
CVE ID:
(no value)
Component:
(no value)
Area:
(no value)
Attachments
0001-dhcpv6-Map-device-aliases-to-parent-interface-for-Li.patch 0001-dhcpv6-Replace-device-aliases-with-parent-interface.patch
Dates
Created:Tue, 17 Jul 2018 10:40:06 -0400
Updated:Fri, 20 Jul 2018 10:55:28 -0400
Closed:Not set

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History
  Tue, 17 Jul 2018 10:40:06 -0400 Marc Dionne <marc.dionne@auristor.com> - Ticket created
Date: Tue, 17 Jul 2018 11:39:55 -0300
From: "Marc Dionne" <marc.dionne@auristor.com>
To: dhcp-bugs@isc.org
Subject: dhcpv6 may ignore requests when there are interface aliases

Hi, I run a dhcpv6 server (package dhcp-server-4.3.6-20.fc28.x86_64 from fedora, kernel 4.17.*) for the purpose of delegating prefixes to my wifi network (Google wifi). This worked fine until I added an interface alias on the server in order to add an additional ipv4 address; the server then failed to respond to SOLICIT packets. As the alias has no ipv6 address (for v6, the kernel keeps all the details with the parent interface and ignores aliases), the dhcp server ignores incoming requests if they are thought to have come in on the alias. Unfortunately, the pktinfo data attached to the packets identifies the alias as the incoming interface. See attached patch for a suggested fix that was verified to work on my network. If the interface identified by the pktinfo data is an alias, find the parent interface and use that instead. Note that independently of this workaround, it is possibly something that should be fixed in the kernel, as it doesn't seem right to identify an interface that doesn't have an ipv6 interface as the source of packets. Thanks, Marc
0001-dhcpv6-Replace-device-aliases-with-parent-interface.patch

Message body is not shown because sender requested not to inline it.

  Wed, 18 Jul 2018 16:08:59 -0400 Marc Dionne <marc.dionne@auristor.com> - Correspondence added
Date: Wed, 18 Jul 2018 17:08:53 -0300
From: "Marc Dionne" <marc.dionne@auristor.com>
Subject: Re: [ISC-Bugs #47957] AutoReply: dhcpv6 may ignore requests when there are interface aliases
To: dhcp-confidential@isc.org

On Tue, Jul 17, 2018 at 11:40 AM, DHCP Bugs via RT <dhcp-confidential@isc.org> wrote: > Greetings, > > This message was automatically generated to acknowledge receipt of > your recent email > "dhcpv6 may ignore requests when there are interface aliases", > and to let you know that we have opened a ticket for your request > (a summary of which appears below.) > > We do not need a further response from you at this time, but if you > do respond, please include in the Subject of your reply the ID > '[ISC-Bugs #47957]' > so that we can match up your reply with the ticket in our system. > > > Hi, > > I run a dhcpv6 server (package dhcp-server-4.3.6-20.fc28.x86_64 from > fedora, kernel 4.17.*) for the purpose of delegating prefixes to my > wifi network (Google wifi). This worked fine until I added an > interface alias on the server in order to add an additional ipv4 > address; the server then failed to respond to SOLICIT packets. > > As the alias has no ipv6 address (for v6, the kernel keeps all the > details with the parent interface and ignores aliases), the dhcp > server ignores incoming requests if they are thought to have come in > on the alias. Unfortunately, the pktinfo data attached to the packets > identifies the alias as the incoming interface. > > See attached patch for a suggested fix that was verified to work on my > network. If the interface identified by the pktinfo data is an alias, > find the parent interface and use that instead. > > Note that independently of this workaround, it is possibly something > that should be fixed in the kernel, as it doesn't seem right to > identify an interface that doesn't have an ipv6 interface as the > source of packets. > > Thanks, > Marc > > Having looked into it a bit further, this is really a dhcpd issue. I noticed that there is code to map alias names to the parent name, but it's inside a section that is only compiled for Solaris afaict. See attached patch for an alternate fix; not sure if this could have other side effects. Marc
0001-dhcpv6-Map-device-aliases-to-parent-interface-for-Li.patch

Message body is not shown because sender requested not to inline it.

Wed, 18 Jul 2018 16:09:00 -0400 The RT System itself - Status changed from 'new' to 'open'
Thu, 19 Jul 2018 07:43:57 -0400 Thomas Markwalder <tmark@isc.org> - Versions Planned 4.4.2 added
Thu, 19 Jul 2018 07:43:59 -0400 Thomas Markwalder <tmark@isc.org> - Queue changed from #8 to dhcp-public
  Fri, 20 Jul 2018 10:55:28 -0400 Thomas Markwalder <tmark@isc.org> - Correspondence added

Hello Marc: Thank you for reporting the matter and taking the time to construct and include a possible patch for it. We will look into it and if a change is warranted we'll try to include it in our next maintenance release, 4.4.2 (schedule TBD). Regardless of the outcome, we'll update you via this ticket with our decision. Again our thanks for your contribution. Our user community has always played a big role in the usefulness and quality of our software. Sincerely, Thomas Markwalder ISC Software Engineering