flow-fanout (1) - Linux Manuals

flow-fanout: Fanout (replicate) flow exports to many destinations.


flow-fanout - Fanout (replicate) flow exports to many destinations.


flow-fanout [ -h ] [ -A AS0_substitution ] [ -d debug_level ] [ -f filter_fname ] [ -F filter_definition ] [ -m privacy_mask ] [ -p pidfile ] [ -s ] [ -S stat_interval ] [ -V pdu_version ] [ -x xmit_delay ] localip/remoteip/port localip/remoteip/port...


The flow-fanout utility will replicate flows arriving on localip/remoteip/port to destination(s) specified by localip/remoteip/port.

Flows processed by multiple exporters will be mixed into a single output stream. This functionality appeared to support Cisco Catalyst exports and may have other uses.

A SIGQUIT or SIGTERM signal will cause flow-fanout to exit.


-A AS0_substitution
Cisco's NetFlow exports represent the local autonomous system as 0 instead of the real value. This option can be used to replace the 0 in the export with the a configured value. Unfortunately under certain configurations AS 0 can also represent a cache miss or non forwarded traffic so use with caution.
-d debug_level
Enable debugging.
-f filter_fname
Filter list filename. Defaults to /etc/flow-tools/cfg/filter.
-F filter_definition
Select the active definition. Defaults to default.
Display help.
-m privacy_mask
Apply privacy_mask to the source and destination IP address of flows. For example a privacy_mask of would convert flows with source/destination IP addresses and to and respectively.
-p pidfile
Configure the process ID file. Use - to disable pid file creation.
Spoof the source IP address. If the IP address is 0 then it is replaced with the exporter source IP.
-S stat_interval
When configured flow-fanout will emit a timestamped message on stderr every stat_interval minutes indicating counters such as the number of flows received, packets processed, and lost flows.
-V pdu_version
Use pdu_version format output.

    1    NetFlow version 1 (No sequence numbers, AS, or mask)
    5    NetFlow version 5
    6    NetFlow version 6 (5+ Encapsulation size)
    7    NetFlow version 7 (Catalyst switches)
    8.1  NetFlow AS Aggregation
    8.2  NetFlow Proto Port Aggregation
    8.3  NetFlow Source Prefix Aggregation
    8.4  NetFlow Destination Prefix Aggregation
    8.5  NetFlow Prefix Aggregation
    8.6  NetFlow Destination (Catalyst switches)
    8.7  NetFlow Source Destination (Catalyst switches)
    8.8  NetFlow Full Flow (Catalyst switches)
    8.9  NetFlow ToS AS Aggregation
    8.10 NetFlow ToS Proto Port Aggregation
    8.11 NetFlow ToS Source Prefix Aggregation
    8.12 NetFlow ToS Destination Prefix Aggregation
    8.13 NetFlow ToS Prefix Aggregation
    8.14 NetFlow ToS Prefix Port Aggregation
    1005 Flow-Tools tagged version 5
-x xmit_delay
Configure a microsecond transmit delay between packets. This may be necessary in some configurations to prevent a transmit buffer overrun.


Replicate flows arriving to local IP address from the router exporting with IP address on port 9500 to localhost port 9500 and port 9200. The exports sent to will be sent with a source IP address of which must be a valid local IP address.

flow-fanout 0/0/9500


NetFlow exports do not contain the exporter IP address inside the payload so the original exporter IP address (typically a router) will be lost when using flow-fanout. A work around for this protocol limitation is to use local IP aliases and the localip option. When the spoofing option is used multiple exporters with different IP addresses will share the same sequence number but will have the original source IP. Fixing this requires per source : destination sequence number mapping. It is much easier to just use multiple instances of flow-fanout running on different ports.


Mark Fullmer <maf [at] splintered.net>