[c-nsp] Identifying IGP passive interfaces via SNMP

[Kevin Graham]

Does anyone know of a way to identify passive (either OSPF or EIGRP
being my interest) interfaces via SNMP? With OSPF-MIB restricting
ospfIfHelloInterval to a lower bound of 1s, a '0' hello interval
isn't possible, and I believe EIGRP has a similar limitation.

I'd like to have a stateless/config-less 'missing neighbors'
monitoring check that would simply ensure that every non-passive
interface has at least one adjacency. The only case that this
wouldn't address out of the box would be a fault-partitioned
multi-access link of 4 or more routers, which in my case is <5%
of links.

Alternatively, how do others address this? (With GRE-in-IPSec not
supporting keepalives, the cop-out solution of just watching link
state isn't an option).