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NG_NETFLOW(4)	       FreeBSD 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 DLT_RAW (raw IP datagrams) and DLT_EN10MB	(Ethernet).  DLT_ def-
	  initions can be found	in <net/bpf.h> header.	Currently used values
	  are 1	for DLT_EN10MB and 12 for DLT_RAW.  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 mes-
	  sage send operation will return an error.

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

	      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 argument:

	      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_INGRESS	      1
	      #define NG_NETFLOW_CONF_EGRESS	      2
	      #define NG_NETFLOW_CONF_ONCE	      4
	      #define NG_NETFLOW_CONF_THISONCE	      8
	      #define NG_NETFLOW_CONF_NOSRCLOOKUP     16
	      #define NG_NETFLOW_CONF_NODSTLOOKUP     32

	  Configuration	is a bitmask of	several	options.  Option NG_NET-
	  FLOW_CONF_INGRESS enabled by default enables ingress NetFlow genera-
	  tion (for data coming	from ifaceX hook).  Option
	  NG_NETFLOW_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	netflow	node.
	  Option NG_NETFLOW_CONF_THISONCE defines that packet should be	ac-
	  counted only once if it several times	passes via exactly this	net-
	  flow node.  These two	options	are important to avoid duplicate ac-
	  counting when	both ingress and egress	NetFlow	are enabled.  Option
	  NG_NETFLOW_CONF_NOSRCLOOKUP skips radix lookup on flow source	ad-
	  dress	used to	fill in	network	mask.  Option
	  NG_NETFLOW_CONF_NODSTLOOKUP skips radix lookup on destination	(which
	  fills	egress interface id, destination mask and gateway).  If	one
	  doesn't need data provided by	lookups, he/she	can disable them, to
	  reduce load on routers.

     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	packets	count
	  between re-announcing	data templates.

     NGM_NETFLOW_SETMTU	(setmtu)
	  Sets export interface	MTU to build packets of	specified size (Net-
	  Flow 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

     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/

     setfib(2),	netgraph(4), 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.

     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.

FreeBSD	13.0		       December	10, 2012		  FreeBSD 13.0


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