I am looking for a C++ library set to develop my own C++ daemon in Linux for collecting NetFlow information. Does anyone know of an open source one or a library set that is available?
Many thanks
Have you tried Googling? There are plenty of daemons for NetFlow available, for Linux and BSD flavors:
For a stand-alone library, you can try "libipfix". It implements the newer IETF IPFIX protocol, but also understands Netflow v9 (on which IPFIX is based). But I don't think it can process older Netflow versions (v1 and v5 are common), so this is probably only useful if your Netflow-exporting devices support Netflow v9.
FWIW - take a look also at http://code.google.com/p/flowd/ - it's small and BSD-licensed, so you should be able to tweak it according to your needs. (I'm not affiliated with it at all, just used a few times, and liked the tiny footprint).
"Vermont" is an open source modular Ipfix/Netflow probe/aggregator/collector application written in C++. It can be configured in a wide variety of ways to collect and process flow related information. It has reasonable documentation with examples detailing how to combine it's modules.