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nfcapd

NAME

nfcapd - netflow capture daemon

SYNOPSIS

nfcapd [options]

DESCRIPTION

nfcapd

is the netflow capture daemon of the nfdump tools. It reads netflow data from the network and stores it into files. The output file is automatically rotated and renamed every n minutes - typically 5 min - according the timestamp YYYYMMddhhmm of the interval e.g. nfcapd.200407110845 contains the data from July 11th 2004 08:45 onward.

Netflow version v5, v7 and v9 are transparently supported.

OPTIONS

-p portnum

Specifies the port number to listen. Default port is 9995

-b bindhost

Specifies the hostname/IPv4/IPv6 address to bind for listening. Can be an IP address or a hostname, resolving to an IP address attached to an interface. Defaults to any available IPv4 interface, if not specified.

-4

Forces nfcapd to listen on IPv4 addresses only. Can be used together with -b if a hostname has an IPv4 and IPv6 address record.

-6

Forces nfcapd to listen on IPv6 addresses only. Can be used together with -b if a hostname has an IPv4 and IPv6 address record.

-j MulticastGroup

Join the specified IPv4 or IPv6 multicast group for listening.

-R host[/port}

Enable packet repeater. Send all incoming packets to another host and port. host is either a valid IPv4/IPv6 address, or a valid symbolic hostname, which resolves to a IPv6 or IPv4 address. port may be ommited and defaults to port 9995. Note: Due to IPv4/IPv6 accepted addresses the port separator is '/'.

-l base_directory

Specifies the base directory to store the output files. Default is /var/tmp If a sub hierarchy is specified with -S the final directory is concatenated to base_directory/sub_hierarchy

-S <num>

Allows to specify an additional directory sub hierarchy to store the data files. The default is 0, no sub hierarchy, which means the files go directly in the base directory (-l). The base directory (-l) is concatenated with the specified sub hierarchy format to form the final data directory. The following hierarchies are defined:

 0 default     no hierachy 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

Specifies the time interval in seconds to rotate files. The default value is 300s ( 5min ).

-w

Align file rotation with next n minute ( specified by -t ) interval. Example: If interval is 5 min, sync at 0,5,10... wall clock minutes Default: no alignment.

-x cmd

Run command cmd at the end of every interval, when a new file becomes available. The following command expansion is available:

%f     Replaced by the file name e.g nfcapd.200407110845 inluding any


     sub hierachy. ( 2004/07/11/nfcapd.200407110845 )
%d     Replaced by the directory where the file is located.

%t     Replaced by the time ISO format e.g. 200407110845.

%u     Replaced by the UNIX time format.

%i     Replaced ident string given by -I

-e

Auto expire files at every cycle. max lifetime and max filesize are defined using nfexpire(1)

-P pidfile

Specify name of pidfile. Default is no pidfile.

-D

Daemon mode: fork to background and detach from terminal. Nfcapd terminates on signal TERM, INT and HUP.

-u userid

Change to the user userid as soon as possible. Only root is allowed to use this option.

-g groupid

Change to the group groupid as soon as possible. Only root is allowed use this option.

-I IdentString

Specifies an ident string, which describes the source e.g. the name of the router. This string is put into the stat record to identify the source. Default is 'none'.

-B bufflen

Specifies the socket input buffer length in bytes. For high volume traffic ( near GB traffic ) it is recommended to set this value as high as possible ( typically > 100k ), otherwise you risk to lose packets. The default is OS ( and kernel ) dependent.

-E

Print netflow records in nfdump raw format to stdout. This option is for debugging purpose only, to see how incoming netflow data is processed and stored.

-z

Compress flows. Use fast LZO1X-1 compression in output file.

-V

Print nfcapd version and exit.

-h

Print help text to stdout with all options and exit.

RETURN VALUE

Returns 0 on success, or 255 if initialization failed.

LOGGING

nfcapd logs to syslog with SYSLOG_FACILITY LOG_DAEMON For normal operation level 'warning' should be fine. More information is reported at level 'info' and 'debug'.

A small statistic about the collected flows, as well as errors are reported at the end of every interval to syslog with level 'info'.

EXAMPLES

nfcapd -z -w -D -l /netflow/spool/router1 -S "%Y/%m/%d/%H"

nfcapd -w -D -l /netflow/spool/router1 -p 23456 -B 128000 -I router1 -x '/path/nfprofile -p /to/profile/dir -s router1 -r %d/%f' -P /var/run/nfcapd/nfcapd.router1

NOTES

Even with netflow v9 support, not all defined elements are stored in the data files. Current version of nfdump supports the following fields:

NF9_LAST_SWITCHED
NF9_FIRST_SWITCHED
NF9_IN_BYTES
NF9_IN_PACKETS
NF9_FLOWS
NF9_IN_PROTOCOL
NF9_SRC_TOS
NF9_TCP_FLAGS
NF9_IPV4_SRC_ADDR
NF9_IPV6_SRC_ADDR
NF9_IPV4_DST_ADDR
NF9_IPV6_DST_ADDR
NF9_L4_SRC_PORT
NF9_L4_DST_PORT
NF9_INPUT_SNMP
NF9_OUTPUT_SNMP
NF9_SRC_AS
NF9_DST_AS

32 and 64 bit counters are supported for Bytes and Packets. More fields may be supported in future.

The format of the data files is netflow version independant.

Socket buffer: Setting the socket buffer size is system dependent. When starting up, nfcapd returns the number of bytes the buffer was actually set. This is done by reading back the buffer size and may differ from what you requested.

SEE ALSO

nfdump(1), nfprofile(1), nfreplay(1)

BUGS

I only found the second last bug. Please report the last one back to me.