Right now flow tables use a set of devices to select the table structure.
It Would Be Nice™ to be able to specify at least one group ID(s) either
as a replacement for devices= or in addition to it, that would select
the candidate devices.
With a group id selector dynamic interfaces (ppp, ppoe, or the *.staN
interfaces created by hostapd on a 4addr segment) can come and go
without having to reload or update the set of active rules.
The structure of the running table doesn't change since each active
entry is still interface-to-interface, but the table building logic in
the accept stanza would include the group number check when needed.
