OSPF v3 support in check_ospf_nbr
The check_ospf_nbr plugin should support checking OSPF v3 neighbours in addition to v2 neighbours, and it should be possible to check both OSPF v2 and v3 at the same time. I.e, all three of
check_ospf_nbr -2 -N 1.2.3.4
check_ospf_nbr -3 -N 1.2.3.4
check_ospf_nbr -2 -3 -N 1.2.3.4
should be work, and the latter would check that there is adjacencies with router 1.2.3.4 both for both v2 and v3, and signal an error if either is missing.
We will probably need to extract a MIB file for OSPFv3 from RFC 5643 and ship it together with the plugin, as it seems difficult to find one on the internets, and none seem to be packaged for RHEL/EPEL.