Eibd provides over a TCP/IP and/or unix domain sockets access to the
EIB/KNX-bus using a simple protocol. It provides access at layer 4 as
well as to high level mangement function. Multiple concurrent users
are supported. A special bus monitor mode call vBusmonitor is
implemented, which delivers all traffic, which eibd passes, but not
disturbs send activities.

Additionally, eibd can act as limited EIBnet/IP Tunneling and/or Routing
Server. The limitation is, that only one KNX address can be used as source
address of EIBnet/IP Clients. This address is shared between multiple
possible routing or tunneling connections. To the EIBnet/IP client,
the address 0.0.0 is used, to the EIB/KNX bus the address of the interface
device is used. eibd maps between these addresses (like NAT for TCP/IP).

Enabling the EIBnet/IP Server disables the normal bus monitor function
(vBusmonitor still works). It supports all interfaces supported by eibd.
In an experiment, the ETS read successfully the device infos over
EIBnet/IP Tunneling to a chain of some eibds connected through
EIBnet/IP Tunneling and a TPUART at the last. 

https://www.auto.tuwien.ac.at/~mkoegler/index.php/eibd