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NAME

     ng_netflow - Cisco’s NetFlow implementation

SYNOPSIS

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

DESCRIPTION

     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.

HOOKS

     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
     received on iface* hooks.  If corresponding 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 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.

CONTROL MESSAGES

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

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

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

     NGM_NETFLOW_SETDLT
             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.

     NGM_NETFLOW_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
             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 index 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 {
                         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.

     NGM_NETFLOW_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;
                         uint32_t        active_timeout;
                 };

     NGM_NETFLOW_SHOW
             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.

ASCII CONTROL MESSAGES

     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 }"

SHUTDOWN

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

EXAMPLES

     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/10.0.0.1:4444
           SEQ

     This is a more complicated example of a router with 2 NetFlow-enabled
     interfaces fxp0 and ng0.  Note that the ng0: node in this example is
     connected 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/10.0.0.1:4444
           SEQ

SEE ALSO

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

     http://www.cisco.com/univercd/cc/td/doc/cisintwk/intsolns/netflsol/nfwhite.htm

AUTHORS

     The ng_netflow node type was written by Gleb Smirnoff
     〈glebius@FreeBSD.org〉, based on ng_ipacct written by Roman V. Palagin
     〈romanp@unshadow.net〉.

BUGS

     Cache snapshot obtained via NGM_NETFLOW_SHOW command may lack some
     percentage 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.