nprobe --collector-port 2055 --collector 127.0.0.1:2055 -V 9
In proxy mode it is possible to convert from/to IPFIX/NetFlow v5/v9 in order to smoothly upgrade to newer NetFlow protocol versions while capitalizing on previous protocol versions. So you can for instance convert flows coming from your v5 router into IPFIX and vice-versa. Note that with some combinations (e.g. from v9 to v5) you might lose some flow information.