[Bug 1070154] [NEW] if-up turns off accept_ra when using stateful DHCP

[David Burns]

Public bug reported:

When using "inet6 dhcp" in /etc/network/interfaces, ifup always sets

    sysctl net.ipv6.conf.%iface/.//%.accept_ra=0

This seems to assume that DHCP will always be able to provide a default
route, which is not always true (This was forbidden in the DHCPv6 RFC)
or desirable (The IPv6 routers sending RAs might have more up to date
information about their own availability than the DHCPv6 server.

There should be an option which uses stateful DHCP to get an IPv6
address, but which still uses RA to find routers.  I think that it's
most intuitive that this be called "DHCP" and leave "auto" for the
stateless variety.  If accept_ra needed to be turned off, I think that
this would better be done by dhclient, since that daemon would know if
it received and installed a default route.

** Affects: ifupdown (Ubuntu)
     Importance: Undecided
         Status: New


** Tags: dhcp ifup ipv6

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https://bugs.launchpad.net/bugs/1070154

Title:
  if-up turns off accept_ra when using stateful DHCP

Status in “ifupdown” package in Ubuntu:
  New

Bug description:
  When using "inet6 dhcp" in /etc/network/interfaces, ifup always sets

      sysctl net.ipv6.conf.%iface/.//%.accept_ra=0

  This seems to assume that DHCP will always be able to provide a
  default route, which is not always true (This was forbidden in the
  DHCPv6 RFC) or desirable (The IPv6 routers sending RAs might have more
  up to date information about their own availability than the DHCPv6
  server.

  There should be an option which uses stateful DHCP to get an IPv6
  address, but which still uses RA to find routers.  I think that it's
  most intuitive that this be called "DHCP" and leave "auto" for the
  stateless variety.  If accept_ra needed to be turned off, I think that
  this would better be done by dhclient, since that daemon would know if
  it received and installed a default route.

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