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preferred_ranges

preferred_ranges sets the priority order for underlay IP addresses. Two hosts on the same LAN would likely benefit from having their tunnels use the LAN IP addresses rather than the public IP addresses the lighthouse may have learned for them. preferred_ranges accepts a list of CIDR ranges admitted as a set of preferred ranges of IP addresses.

An underlay network is the network that a nebula overlay network maps onto. It is the LAN network that a host is connected to in addition to the wider internet.

How nebula orders underlay IP addresses it learns about​

Ordered from highest to lowest priority:

  1. IP address is in preferred_ranges set and is ipv6
  2. IP address is in preferred_ranges set and is public ipv4
  3. IP address is in preferred_ranges set and is private ipv4
  4. IP address is ipv6
  5. IP address is public ipv4
  6. IP address is private ipv4
  7. Route is via a relay (experimental)

To set up a host that prefers local network 172.16.0.0/24 first, then ipv6 then public ipv4 then private ipv4, specify:

preferred_ranges: ['172.16.0.0/24']

This would add the network range 172.16.0.0/24 to the preferred_ranges set, which nebula will use to influence its ranking of options for underlay connections. If multiple types of ranges are specified, such as a private ipv4 range and an ipv6 range, they will be sorted as shown above. So, the ipv6 would be given priority, no matter its position in the preferred_ranges set.

info

The previous option local_range only allowed definition of a single range and has been deprecated and replaced by preferred_ranges.