** Changed in: network-manager
       Status: New => Invalid

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https://bugs.launchpad.net/bugs/1038541

Title:
  Network Manager copies IPv6 route cache entries to main routing table

Status in NetworkManager:
  Invalid
Status in “network-manager” package in Ubuntu:
  Confirmed

Bug description:
  Any time an IPv6 route lookup happens, the kernel generates a new
  routing cache entry and notifies userspace using a netlink "new route"
  message with the RTM_F_CLONED flag set on the route.

  Network Manager doesn't check for this flag, so it accepts it as a new
  real route and adds it to its internal route cache. Then, because the
  event triggers an interface update, it synchronizes its route cache
  with the kernel table, putting the cache entry in as a real host
  route.

  I think NM might also overwrite the next hop of the route based on its
  internal idea of the default route, but I'm not sure.

  This causes problems if you have interfaces not managed by
  NetworkManager, such as manually configured VPNs, since these host
  routes override the route entries that send traffic down those
  interfaces rather than to the default router.

  To reproduce:
  Ensure "Ignore automatically obtained routes" is unchecked in Edit Connection 
-> IPv6 -> Routes, because this blocks the last stage (copying the spurious 
route back to the kernel).
  Connect to an IPv6 network.
  run `ip -6 route` and observe no extra routes
  run `ip -6 route get 2600::`
  run `ip -6 route` again and observe the new static route to 2600:: via your 
default gateway

  Expected behavior:
  No changes to routing table due to a route lookup.

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