[Bug 1013597] Re: No default route for stateful DHCPv6

Ray Soucy rps at maine.edu
Fri Sep 21 18:48:28 UTC 2012


Can we change the status of this bug so it doesn't show up as "Fix
Released"

It needs more attention.

> Ok, found new conf parameters for dhcp stanza accept_ra and 
> autoconf - that solves RA issue. Still investigating release.

I tried adding the "accept_ra 1" option to /etc/network/interfaces and
it was ignored by ifupdown:

iface eth0 inet6 dhcp
    accept_ra 1

The accept_ra option should default to 1 not 0
Also, the dhclient release bug is annoying as well.  The workarounds in the description don't seem to work completely either (dhclient doesn't like seeing the interface bounce while it's making a request).

I have ifupdown listed as package version 0.7~beta2ubuntu8 for amd64

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https://bugs.launchpad.net/bugs/1013597

Title:
  No default route for stateful DHCPv6

Status in “ifupdown” package in Ubuntu:
  Fix Released

Bug description:
  The default route cannot be provided via DHCPv6, it must be obtained
  from router advertisements. However, when using the dhcp method for
  inet6 in /etc/network/interfaces (e.g. "iface eth0 inet6 dhcp"), ifup
  will set net.ipv6.conf.<IFACE>.accept_ra=0, resulting in no default
  route for IPv6. Instead, it should explicitly set accept_ra=1.

  A workaround is to set it in a post-up script. However, Linux
  apparently only sends router solicitations when the interface is
  brought up, so if unsolicited RA:s are infrequent the host will be
  without a default route until the next RA.

  Another problem is that when bringing the interface down on dual-stack
  hosts, there will be a long timeout. This is because bringing down
  IPv4 also brings the interface link down, and afterwards dhclient
  cannot release the DHCPv6 lease due to the link being down ("RTNETLINK
  answers: Cannot assign requested address"). The workaround is to bring
  the link back up before bringing IPv6 down.

  So the workarounds (which obviously should not be needed) for a dual-
  stack dhcp client look like this:

  iface eth0 inet dhcp
  iface eth0 inet6 dhcp
      up sysctl net.ipv6.conf.$IFACE.accept_ra=1
      pre-down ip link set dev $IFACE up

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