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NFANON(1) General Commands Manual NFANON(1)

NAME

nfanonanonymize the IP addresses

SYNOPSIS

nfanon -r path [-w nffile] -K key [-C config] [-s] [-d] [-q] [-t num] [-v level] [-W] [-h]

DESCRIPTION

nfanon anonymizes all IP addresses ( src, dst, next hop, router IP etc. ) in the netflow records using the CryptoPAn (Cryptography-based Prefix-preserving Anonymization) module. The key -K is used to initialize the Rijndael cipher. The key is either a 32 character string, or a 64 hex digit string starting with 0x. See https://en.wikipedia.org/wiki/Crypto-PAn for more information on CryptoPAn.

The source specified by argument -r path may point to a single nfdump file or to a directory containing many nfdump files. All files in a directory are processed recursively.

If the output argument -w nffile is given, all anonymized records are written into that single file, even if the source is a directory. If no argument -w is specified, nfanon overwrites the original source file with the anonymized flow records. If the source is a directory, each flow file is anonymized respectively.

The options are as follows:

path
Path to read flow files to anonymize. Path may point to a single file or a directory containing many flow files.
nffile
File name to write anonymized flow records to. If this argument is missing, the source file name is taken, which means the original file is overwritten.
key
key is either a 32 character string, or a 64 char hex string starting with 0x. This key is used to initialize the anonymizer.
level
Set verbose level. A verbose level of 0 disables the activity spinner.
num
Set the number of worker threads. The default depends on the number of cores online. The value must not exceed the number of online CPU cores.

Worker threads are used to anonymize flow records in parallel.

config
Read configuration from config; use to suppress configuration-file loading.
Preserve source addresses rather than anonymising them.
Preserve destination addresses rather than anonymising them.
Deprecated compatibility option; it is rejected. Use -v -0 for quiet logging.
num
Legacy alias for -W num.
Print help text to stdout and exit.

EXIT STATUS

nfanon returns 0 on success and 255 otherwise.

EXAMPLES

To create a random 64 character hex string you may use the following command:

% xxd -u -l 32 -p -c 64 /dev/urandom

Use the resulting output as key, prepended with 0x as -K argument.

Or

% openssl rand -hex 16

and use this output as argument for -K

SEE ALSO

nfdump(1)

September 22, 2026 Linux 6.12.0-160000.37-default