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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 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.

     Export information	is stored in NetFlow version 5 datagrams.

     This node type supports up	to NG_NETFLOW_MAXIFACES	hooks named iface0,
     iface1, etc., and the same	number of hooks	named out0, out1, etc.,	plus a
     single hook named export.	The node does NetFlow accounting of data re-
     ceived on iface* hooks.  If corresponding out hook	is connected, unmodi-
     fied data is bypassed to it, otherwise data is freed.  If data is re-
     ceived on out hook, it is bypassed	to corresponding iface hook without
     any processing.  When full	export datagram	is built it is sent to the
     export hook.  In normal operation,	the 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:

	     Returns some node statistics and the current timeout values in a
	     struct ng_netflow_info.

	     Returns information about the ifaceN hook.	 The hook number is
	     passed as an argument.

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

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

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

	     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 {
			 u_int16_t iface;	 /* which iface	to operate on */
			 u_int16_t index;	 /* new	index */

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

	     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;
			 uint32_t	 active_timeout;

	     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.

     Most binary control messages have an ASCII	equivalent.  The supported
     ASCII commands are:

     NGM_NETFLOW_INFO	      "info"
     NGM_NETFLOW_IFINFO	      "ifinfo %u"
     NGM_NETFLOW_SETDLT	      "setdlt {	iface =	%u dlt = %u }"
     NGM_NETFLOW_SETIFINDEX   "setifindex { iface = %u index = %u }"
     NGM_NETFLOW_SETTIMEOUTS  "settimeouts { inactive =	%u active = %u }"

     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
     ether 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), ng_ksocket(4), ng_tee(4), flowctl(8),	ngctl(8)

     The ng_netflow node type was written by Gleb Smirnoff
     <>, 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.

BSD				 May 11, 2005				   BSD


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