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

[Thiago Martins]

Guys, sorry if I was rude before... Too much things happening at the
same time today...    :-P

I just installed a PFSense 2.1 with IPv6 and, for my surprise, Debian
and Ubuntu Server are the only two operating systems that doesn't work
"out-of-the-box" in a IPv6-Only network...

Ubuntu Desktop, Windows 7, Mac, are okay in a IPv6-Only env... Debian
and Ubuntu (during the installation process, and even after) doesn't.


I mean, I tried to Install Ubuntu using the following scenarios:


1- SLAAC Unmanaged (no RDNSS) - Ubuntu Server have IPv6 addr without DNS resolution, of course (expected) - connectivity okay;

2- SLAAC Unmanaged + RDNSS - Ubuntu Server have IPv6 but no DNS name
resolution (i.e. it ignore RDNSS entries from RadvD) - connectivity
okay;

3- SLAAC Managed + DHCPv6 Statefull - Ubuntu Server (or Debian) get its
IPv6 addr, DNS servers too but, the connectivity only starts after
"ping6 my_ipv6_gateway" - NO CONNECTIVITY UNTIL PING6 GATEWAY!!


So, I'm seeing that there is no option to install Ubuntu (or Debian) in a IPv6-Only network without suffering some issues (that can be fixed after install, I know, but it is annoying). Also, we need a IPv6-Enabled NTP server too...    =P

I'm okay with SLAAC-Only deployments but, huge organizations seems to
require DHCPv6 for getting more info about its network services
automatically and SLAAC doesn't provides it (not designed for it)...

As I said, my IPv6 router is a brand new PFSense 2.1 with "RadvD +
DHCPv6 (on LAN)" and it is working fine, since I have more machines here
working smoothly with IPv6 from behind it. For each scenario above, I've
reconfigured PFSense to match it (Managed - Unmanaged / with - without
DHCPv6).

NOTE: There is no IPv4 on this enviroment.

Best!
Thiago

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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
Status in “ifupdown” source package in Precise:
  Triaged

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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