Provided by: nfdump_1.7.3-1build2_amd64 
NAME
nfcapd — flow collector for netflow version v1, v5/v7 v9 and ipfix
SYNOPSIS
nfcapd -w flowdir [-C config] [-z=<compress>] [-D] [-u userid] [-g groupid] [-S num] [-t interval]
[-P pidfile] [-p port] [-d device] [-I ident] [-b bindhost] [-f flowfile] [-4] [-6]
[-J mcastgroup] [-R repeater] [-A] [-B buffsize] [-n sourceparam] [-M multiflowdir] [-s rate]
[-i metricrate] [-m metricpath] [-e] [-x command] [-X extensionList] [-E] [-v] [-V]
DESCRIPTION
nfcapd reads netflow data from the network and stores the records into binary formatted files. It
accepts netflow v1, v5/v7, v9 and ipfix transparently. It is mostly compatible with a lot of other flow
implementations such as cflow, jflow, pflow and accepts a wide range of exporters including CISCO
Flexible Netflow (FNF), ASA firewalls and NAT devices for event logging. It has also support for a wide
range of different vendors and their implementation of netflow, such as Juniper, VMware, PaloAlto devices
and yaf. Sflow is a different technology. nfcapd supports a large number of netflow v9 and ipfix
elements according to the IANA assignments.
If you want to collect sflow data, please have a look at sfcapd which is also part of the nfdump tools.
nfcapd also accepts pre-processed records from its companion collector nfpcapd. nfcapd safes the flows
in an output file, which is automatically rotated at a given interval - typically every 5min. These
rotated output files are stored in the flowdir directory and are organized by timestamps. The output
files are named according to the time interval in the following format: nfcapd.YYYYMMddhhmm e.g.
nfcapd.202207110845 which contains flow data from July 11th 2022 08:45 onwards. If the rotation interval
is set to a time, smaller then 60s, the naming extends to seconds e.g. nfcapd.20220711084510.
nfcapd can run in auto-expire mode -e , which automatically expires old flow files, at the end of every
rotation interval. nfexpire(1) explains in more details how to setup flow expiration.
nfcapd can run any given command -x or shell script at the end of each rotation interval.
nfcapd can send universal flow metric information about the collected flow data (flow summary) to a UNIX
socket. Programs, such as nfinflux or nfexporter may be used to send the metric information to an
InfluxDB or to a Prometheus monitoring system.
The options are as follows:
-w flowdir
Set the flow directory to store the output files. If a sub hierarchy is specified with -S the
final directory is concatenated to flowdir/subdir.
-C config
Reads additional configuration parameters from config file. nfcapd tries to read the config file
from the install default path $prefix/etc/ which may be overwritten by the environment variable
NFCONF , which again is overwritten by this option -C. If -C none is specified, then no config
file is read, even if found in the search path.
-p portnum
Set the port number to listen. Default port is 9995
-d interface
Reads flow data from an erspan encoded datalink. All traffic sent to this interface is
interpreted as flow data stream.
-b bindhost
Specifies the hostname/IPv4/IPv6 address to bind for listening. This can be an IP address or a
hostname, resolving to a local IP address.
-4 Forces nfcapd to listen on IPv4 addresses only. Can be used together with -b if a hostname has
IPv4 and IPv6 addresses.
-6 Forces nfcapd to listen on IPv6 addresses only. Can be used together with -b if a hostname has
IPv4 and IPv6 addresses.
-J mcastgroup
Join the specified IPv4 or IPv6 multicast group for listening.
-R host[/port]
Enables the packet repeater. All incoming packets are sent additionally to another host and port.
host is either a valid IPv4/IPv6 address, or a symbolic hostname, which resolves to a valid IP
address. port may be omitted and defaults to 9995. Note: As IPv4/IPv6 are accepted the host/port
separator is '/'. Up to 8 additional repeaters my be defined. Use this method to daisy chain
collectors.
-A Sets source address spoofing mode for the repeater. The source address of the repeated packages
is set to the original IP address. This needs nfcapd to be started with root privileges. Please
note, that source spoofing may be blocked by firewalls or routers in your network.
-I ident
Sets ident as identification string for the current source. This string is written into the
output file to identify the source. Default is 'none'. If you have multiple sources, see option
-n below.
-n ident,IP,flowdir
Configures a netflow source identified by the string ident, IP flowdir If you have multiple
sources per collector, add multiple -n options. All exporters send the flows to the same port -p.
Do not mix single source configuration -I with multiple -n options.
-M flowdir
Set the flow directory for dynamic allocated exporters. New exporters are dynamically added when
sending data. All exporters send netflow data to the same port and IP. For each dynamically
added source, a new sub directory is created under flowdir with the name of the IP address of the
exporter. All '.' and ':" in IP addresses are replaced be '-'. -D Set daemon mode: fork to
background and detach from terminal. nfcapd terminates on signal TERM, INT or HUP.
-P pidfile
Writes the running process ID into pidfilw. Use this option to integrate nfcapd in start/stop
files.
-u userid
Drop privileges of running process to user userid. nfcapd needs to be started as user root.
-g groupid
Drop privileges of running process to group groupid. nfcapd needs to be started as user root.
-B bufflen
Sets the network socket input buffer to bufflen bytes. For high volume traffic it is recommended
to raise this value to typically > 100k, otherwise you risk to lose packets. The default is OS
(and kernel) dependent.
-S num Adds an additional directory sub hierarchy to store the data files. The default is 0, no sub
hierarchy, which means all files go directly into flowdir. The flowdir is concatenated with the
specified sub hierarchy format to create the final data directory. The following hierarchies are
defined:
0 default no hierarchy levels
1 %Y/%m/%d year/month/day
2 %Y/%m/%d/%H year/month/day/hour
3 %Y/%W/%u year/week_of_year/day_of_week
4 %Y/%W/%u/%H year/week_of_year/day_of_week/hour
5 %Y/%j year/day-of-year
6 %Y/%j/%H year/day-of-year/hour
7 %Y-%m-%d year-month-day
8 %Y-%m-%d/%H year-month-day/hour
-t interval
Sets the time interval in seconds to rotate files. The default value is 300s ( 5min ). The
smallest available interval is 2s.
-s rate
Apply sampling rate rate to all netflow records, unless the sampling rate is announced by the
exporting device. In that case the announced sampling rate is applied. If rate is negative, this
will hard overwrite any device specific announced sampling rates. The sampling rate is used to
multiply the number of packets and bytes in a record. Please note, this may vary from other
volume counters such as SNMP etc.
-z Compress flow files with LZO1X-1 compression. Fastest compression.
-z=lzo Compress flow files with LZO1X-1 compression. Fastest compression.
-z=lz4 Compress flow files with LZ4 compression. Fast and efficient.
-z=bz2 Compress flow files with bz2 compression. Slow but most efficient. It is not recommended to use
bz2 in a real time capturing.
-e Sets auto-expire mode. At the end of every rotate interval -t nfcapd runs an expire cycle to
delete files according to max lifetime and max filesize as defined by nfexpire(1)
-x command
At the end of every -t interval and after the file rotate has completed, nfcapd runs the command
command. The string for command may contain the following place holders, which are expanded
before running:
%f File name of new data file including any sub hierarchy.
%d Top flowdir. The full path of the new file is: %d/%f
%t Time slot string in ISO format e.g. 201107110845.
%u Time slot string in UNIX time format.
%i Identification string ident string supplied by -I
-X extensionList
extensionList is a ',' separated list of extensions to be stored by nfcapd. The numbers
correspond to the extension list in nfxV3.h. By default extensions are added dynamically to store
all data sent by the exporter. If extensionList is given, only those elements matching the
extension are processed and stored. Usually this option is not needed, unless for specific
requirements.
-m metricpath
Enables the flow metric exporter. Flow metric information is sent to the UNIX socket metricpath
at the rate specified by -i This option may by used to export flow metric information to other
systems such as InfluxDB or Prometheus. Please note: The flow metric does not include the full
record. Only the flow statistics is sent.
-i metricrate
Sets the interval for the flow metric exporter. This interval may be different from the file
rotation interval t and is therefore independent from file rotation.
-v Increase verbose level by 1. The verbose level may be increased for debugging purpose up to 3.
-E Equal to -v -v -v. Print netflow records in block format to stdout. Please note, that not all
elements are printed, which are available in the flow record. To inspect all elements, use nfdump
-o raw This option is for debugging purpose only, to verify if incoming netflow data is processed
correctly.
-V Print nfcapd version and exit.
-h Print help text on stdout with all options and exit.
RETURN VALUES
nfcapd returns 0 on success and 255 if initialization failed.
SEE ALSO
https://www.iana.org/assignments/ipfix/ipfix.xhtml
https://www.cisco.com/en/US/technologies/tk648/tk362/technologies_white_paper09186a00800a3db9.html
nfdump(1) nfpcapd(1) sfcapd(1)
BUGS
No software without bugs! Please report any bugs back to me.
Debian $Mdocdate$ NFCAPD(1)