kplex is a multitransport software data multiplexer, working with
data conforming to the NMEA-0183 standard.

Kplex multiplexes data inputs from sources such as serial lines,
pseudo terminals and network interfaces and send to any (reasonable)
number of similar outputs.

kplex can perform filtering of inputs (so you only get the data you
want, or don't get the data you don't want from a given source) and
outputs (so you only send what you want where you want) and can
perform fine-grained failover so that for any given type of data,
you specify a priority order of the source you would like to take
it from.