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 changing UDP pakets (transparent) 
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Joined: 19 May 2015, 08:24
Posts: 1
A lighting console (eg GrandMA) is sending informations to stage lights using Ethernet.
The common protocol would be "ArtNet" from Artisic Licence, using a closed network (no internet access)
and UDP with port $1936. The lighting informations are inside the UDP data payload.

I need Carambola2 (with OpenWrt) with its 2 ethernet ports (LAN: eth0 and WAN: eth1) to be placed in the ethernet cable like:
ligthing console <-> eth0 ... eth1 <-> lighting equipement.

The carambola2 should work transparent as a router except for UDP pakets with UDP port $1936
(and additional filtering of data payload). These pakets need to be changed before the travel onwards...

I am NEW to Linux/OpenWrt - but I am confirm with programing (C, C++, Pascal, Assembler, Atmel mikrocontrollers...)

Where to start ???

I guess using iptables to redirect incoming UDP pakets for dest port $1936 to a C-app, wich analyses the data payload, does the changes (recalc checksums?) and sends the new datas.

What is the term for the hardware ethernet ports? "port" is a logic term - I guess "interface" is what I am searching for.

It would be possible to define the two ethernet ports like:
LAN (eth0) connects to lighting console (sender) and
WAN (eth1) connects to lighting equipment (reciever)

The other direction (lighting equipment answers the console) should be untouched.

Thank you very much...

PS: If any OpenWrt guru in south germany (Stuttgart) would like to spend some time... 246933

19 May 2015, 09:01
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