The nfdump tools collect and process netflow data on the command line.
Nfdump tools:
nfcapd     - netflow collector daemon
nfdump     - netflow dump
nfprofile  - netflow profiler - optional tool
nfreplay   - netflow replay
nfexpire   - expire old netflow data
nfanon     - netflow anonymisation
ft2nfdump  - read flow-tools format - optional tool
sfcapd     - sflow collector daemon - optional tool

Homepage:
http://nfdump.sourceforge.net/
