kernel interface for pflow data
pflow interface is a pseudo-device
pflow accounting data from the kernel
pflow is compatible with netflow version 5
and IPFIX (10). The data is extracted from the
pflow interfaces can be created
at runtime using the
Each interface must be configured with a flow receiver IP address and a flow
receiver port number.
Only states created by a rule marked with the
pflow keyword are exported by the
pflow interface will attempt to export
pflow records in one UDP packet, but will
not hold a record for longer than 30 seconds. The packet size and thus the
maximum number of flows is controlled by the
parameter of ifconfig(8).
Each packet seen on this interface has one header and a variable
number of flows. The header indicates the version of the protocol, number of
flows in the packet, a unique sequence number, system time, and an engine ID
and type. Header and flow structs are defined in
There is a one-to-one correspondence between packets seen by
bpf(4) on the
pflow interface and packets sent out to the flow
receiver. That is, a packet with 30 flows on
means that the same 30 flows were sent out to the receiver.
pflow source and destination addresses
are controlled by ifconfig(8).
flowsrc is the sender IP
address of the UDP packet which can be used to identify the source of the
data on the
flowdst defines the collector IP address and the
flowdst IP address and port must be
defined to enable the export of flows.
For example, the following command sets 10.0.0.1 as the source and 10.0.0.2:1234 as destination:
# ifconfig pflow0 flowsrc 10.0.0.1 flowdst 10.0.0.2:1234
The protocol is set to IPFIX with the following command:
# ifconfig pflow0 pflowproto 10
netintro(4), pf(4), udp(4), pf.conf(5), ifconfig(8), tcpdump(8)
B. Claise, Specification of the IP Flow Information Export (IPFIX) Protocol for the Exchange of IP Traffic Flow Information, RFC 5101, January 2008.
pflow device first appeared in
A state created by
can have a creation or expiration time before the machine came up. In this
pflow pretends such flows were created or
expired when the machine came up.
The IPFIX implementation is incomplete: The required transport protocol SCTP is not supported. Transport over TCP and DTLS protected flow export is also not supported.