Introduce a verbose output mode to pflowctl, and expose the status of
the socket to userspace. This can be helpful in debugging configuration
errors.
Sponsored by: Rubicon Communications, LLC ("Netgate")
pflow is a pseudo device to export flow accounting data over UDP.
It's compatible with netflow version 5 and IPFIX (10).
The data is extracted from the pf state table. States are exported once
they are removed.
Reviewed by: melifaro
Obtained from: OpenBSD
Sponsored by: Rubicon Communications, LLC ("Netgate")
Differential Revision: https://reviews.freebsd.org/D43106
