We have LUA support for processing/filtering NetFlow flows
It supported only for NetFlow v5 and sFLOW at this moment and enabled by default.
Please be aware! In Ubuntu 14.04 lua-json 1.3.1 is buggy and should be upgraded to 1.3.2.
Fast fix for lua-json for Ubuntu 14.04:
wget https://raw.githubusercontent.com/harningt/luajson/1.3.3/lua/json/decode/util.lua -O/usr/share/lua/5.1/json/decode/util.lua
wget https://raw.githubusercontent.com/harningt/luajson/1.3.3/lua/json/decode/strings.lua -O/usr/share/lua/5.1/json/decode/strings.lua