This adds a configuration flag to skip kernel (sysctl) setup on daemon
startup. This can be useful if running in, e.g., a container environment
where setting sysctls are not allowed.
Signed-off-by: Toke Høiland-Jørgensen <toke@toke.dk>

This reworks the sysctl handling to only write a sysctl if it is not
already the desired value. In addition, the Linux sysctl knobs are now
stored in a lookup table which is looped through, to avoid code
duplication in the setup routine.
Signed-off-by: Toke Høiland-Jørgensen <toke@toke.dk>

There is no equivalent config-file option, since I'm worried about config
files being copied between nodes.

This patch fix the non-disambiguation behaviour: we were looking to
disambiguation entries to remove or replace, which is a complete non-sense,
since there should not being disambiguation entries.

Sigh.

This is simpler and avoids issues with changing router-ids.

This increases the chances for a stable router-id in case the set of
interfaces changes.

This fixes compilation under musl.

This fixes compilation under musl.

Based on the kernel version, can be overridden explicitly.

Prefixes are counted in bits, not in bytes.  It is safe to compare all
16 bytes, since prefixes are always normalised -- they have zeroes beyond
the prefix length, see mask_prefix.  Alternatively, we could use
prefix_cmp.

Was used in the first version of the disambiguation.c algorithm.

This reverts commit 9edf0a14.