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NG_NETFLOW(4)		 BSD Kernel Interfaces Manual		 NG_NETFLOW(4)

     ng_netflow	-- Cisco's NetFlow implementation

     #include <sys/types.h>
     #include <netinet/in.h>
     #include <netgraph/netflow/ng_netflow.h>

     The ng_netflow node implements Cisco's NetFlow export protocol on a
     router running FreeBSD.  The ng_netflow node listens for incoming traffic
     and identifies unique flows in it.	 Flows are distinguished by endpoint
     IP	addresses, TCP/UDP port	numbers, ToS and input interface.  Expired
     flows are exported	out of the node	in NetFlow version 5/9 UDP datagrams.
     Expiration	reason can be one of the following:

     -	 RST or	FIN TCP	segment.

     -	 Active	timeout.  Flows	cannot live more than the specified period of
	 time.	The default is 1800 seconds (30	minutes).

     -	 Inactive timeout.  A flow was inactive	for the	specified period of
	 time.	The default is 15 seconds.

     Node supports IPv6	accounting (NetFlow v9 only) and is aware of multiple
     fibs.  Different fibs are mapped to different domain_id in	NetFlow	V9 and
     different engine_id in NetFlow V5.

     This node type supports up	to NG_NETFLOW_MAXIFACES	(default 65536)	hooks
     named iface0, iface1, etc., and the same number of	hooks named out0,
     out1, etc., plus two export hooks:	export (for NetFlow version 5) and
     export9 (for NetFlow version 9). Export can be done simultaneously	for
     all supported export hooks. By default (ingress NetFlow enabled) node
     does NetFlow accounting of	data received on iface*	hooks.	If correspond-
     ing out hook is connected,	unmodified data	is bypassed to it, otherwise
     data is freed.  If	data is	received on out	hook, it is bypassed to	corre-
     sponding iface hook without any processing	(egress	NetFlow	disabled by
     default).	When full export datagram for an export	protocol is built it
     is	sent to	the export or export9 hook.  In	normal operation, one (or
     more) export hook is connected to the inet/dgram/udp hook of the
     ng_ksocket(4) node.

     This node type supports the generic control messages, plus	the following:

     NGM_NETFLOW_INFO (info)
	     Returns some node statistics and the current timeout values in a
	     struct ng_netflow_info.

     NGM_NETFLOW_IFINFO	(ifinfo)
	     Returns information about the ifaceN hook.	 The hook number is
	     passed as an argument.

     NGM_NETFLOW_SETDLT	(setdlt)
	     Sets data link type on the	ifaceN hook.  Currently, supported
	     types are raw IP datagrams	and Ethernet.  This message type uses
	     struct ng_netflow_setdlt as an argument:

		 struct	ng_netflow_setdlt {
			 uint16_t iface;	 /* which iface	dlt change */
			 uint8_t  dlt;		 /* DLT_XXX from bpf.h */

	     The requested ifaceN hook must already be connected, otherwise
	     message send operation will return	an error.

     NGM_NETFLOW_SETIFINDEX (setifindex)
	     In	some cases, ng_netflow may be unable to	determine the input
	     interface index of	a packet.  This	can happen if traffic enters
	     the ng_netflow node before	it comes to the	system interface's in-
	     put queue.	 An example of such a setup is capturing a traffic
	     between synchronous data line and ng_iface(4).  In	this case, the
	     input index should	be associated with a given hook.  The inter-
	     face's index can be determined via	if_nametoindex(3) from user-
	     land.  This message requires struct ng_netflow_setifindex as an

		 struct	ng_netflow_setifindex {
			 uint16_t iface;	 /* which iface	index change */
			 uint16_t index;	 /* new	index */

	     The requested ifaceN hook must already be connected, otherwise
	     the message send operation	will return an error.

     NGM_NETFLOW_SETTIMEOUTS (settimeouts)
	     Sets values in seconds for	NetFlow	active/inactive	timeouts.
	     This message requires struct ng_netflow_settimeouts as an argu-

		 struct	ng_netflow_settimeouts {
			 uint32_t inactive_timeout;	 /* flow inactive timeout */
			 uint32_t active_timeout;	 /* flow active	timeout	*/

     NGM_NETFLOW_SETCONFIG (setconfig)
	     Sets configuration	for the	specified interface.  This message re-
	     quires struct ng_netflow_setconfig	as an argument:

		 struct	ng_netflow_setconfig {
			 uint16_t iface;	 /* which iface	config change */
			 uint32_t conf;		 /* new	config */
		 #define NG_NETFLOW_CONF_ONCE		 4

	     Configuration is a	bitmask	of several options. Option NG_NET-
	     FLOW_CONF_INGRESS enabled by default enables ingress NetFlow gen-
	     eration (for data coming from ifaceX hook). Option	NG_NET-
	     FLOW_CONF_EGRESS enables egress NetFlow (for data coming from
	     outX hook). Option	NG_NETFLOW_CONF_ONCE defines that packet
	     should be accounted only once if it several times passes via net-
	     flow node.	Option NG_NETFLOW_CONF_THISONCE	defines	that packet
	     should be accounted only once if it several times passes via ex-
	     actly this	netflow	node. Last two options are important to	avoid
	     duplicate accounting when both ingress and	egress NetFlow are en-

     NGM_NETFLOW_SETTEMPLATE (settemplate)
	     Sets various timeouts to announce data flow templates (NetFlow
	     v9-specific). This	message	requires struct	ng_netflow_settemplate
	     as	an argument:

		 struct	ng_netflow_settemplate {
			 uint16_t time;		 /* max	time between announce */
			 uint16_t packets;	 /* max	packets	between	announce */

	     Value of time field represents time in seconds to re-announce
	     data templates.  Value of packets field represents	maximum	pack-
	     ets count between re-announcing data templates.

     NGM_NETFLOW_SETMTU	(setmtu)
	     Sets export interface MTU to build	packets	of specified size
	     (NetFlow v9-specific).  This message requires struct
	     ng_netflow_setmtu as an argument:

		 struct	ng_netflow_setemtu {
			 uint16_t mtu;		 /* MTU	for packet */

	     Default is	1500 bytes.

	     This control message asks a node to dump the entire contents of
	     the flow cache.  It is called from	flowctl(8), not	directly from
	     ngctl(8).	See also BUGS section.

     NGM_NETFLOW_V9INFO	(v9info)
	     Returns some NetFlow v9 related values in a

		 struct	ng_netflow_v9info {
		     uint16_t	     templ_packets;  /*	v9 template packets */
		     uint16_t	     templ_time;     /*	v9 template time */
		     uint16_t	     mtu;	     /*	v9 MTU */

     This node shuts down upon receipt of a NGM_SHUTDOWN control message, or
     when all hooks have been disconnected.

     The simplest possible configuration is one	Ethernet interface, where flow
     collecting	is enabled.

	   /usr/sbin/ngctl -f- <<-SEQ
		   mkpeer fxp0:	netflow	lower iface0
		   name	fxp0:lower netflow
		   connect fxp0: netflow: upper	out0
		   mkpeer netflow: ksocket export inet/dgram/udp
		   msg netflow:export connect inet/

     This is a more complicated	example	of a router with 2 NetFlow-enabled in-
     terfaces fxp0 and ng0.  Note that the ng0:	node in	this example is	con-
     nected to ng_tee(4).  The latter sends us a copy of IP packets, which we
     analyze and free.	On fxp0: we do not use tee, but	send packets back to
     either node.

	   /usr/sbin/ngctl -f- <<-SEQ
		   # connect ng0's tee to iface0 hook
		   mkpeer ng0:inet netflow right2left iface0
		   name	ng0:inet.right2left netflow
		   # set DLT to	raw mode
		   msg netflow:	setdlt { iface=0 dlt=12	}
		   # set interface index (5 in this example)
		   msg netflow:	setifindex { iface=0 index=5 }

		   # Connect fxp0: to iface1 and out1 hook
		   connect fxp0: netflow: lower	iface1
		   connect fxp0: netflow: upper	out1

		   # Create ksocket node on export hook, and configure it
		   # to	send exports to	proper destination
		   mkpeer netflow: ksocket export inet/dgram/udp
		   msg netflow:export connect inet/

     netgraph(4), setfib(2), ng_ether(4), ng_iface(4), ng_ksocket(4),
     ng_tee(4),	flowctl(8), ngctl(8)

     B.	Claise,	Ed, Cisco Systems NetFlow Services Export Version 9, RFC 3954.

     The ng_netflow node type was written by Gleb Smirnoff
     <>, Alexander Motin <>, Alexander
     Chernikov <>.  The	initial	code was based on ng_ipacct
     written by	Roman V. Palagin <>.

     Cache snapshot obtained via NGM_NETFLOW_SHOW command may lack some	per-
     centage of	entries	under severe load.  IPv6 flows are not shown.

     The ng_netflow node type does not fill in AS numbers.  This is due	to the
     lack of necessary information in the kernel routing table.	 However, this
     information can be	injected into the kernel from a	routing	daemon such as
     GNU Zebra.	 This functionality may	become available in future releases.

BSD				  Nov 2, 2012				   BSD


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