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NG_NETFLOW(4) FreeBSD Kernel Interfaces Manual NG_NETFLOW(4)


[править] NAME

    ng_netflow -- Cisco's NetFlow implementation

[править] SYNOPSIS

    #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.

[править] HOOKS

    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:
            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 message 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
            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 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;
            Sets configuration for the specified interface.  This message
            requires struct ng_netflow_setconfig as an argument:
                struct ng_netflow_setconfig {
                        u_int16_t iface;
                        u_int32_t conf;
                #define NG_NETFLOW_CONF_INGRESS         1
                #define NG_NETFLOW_CONF_EGRESS          2
                #define NG_NETFLOW_CONF_ONCE            4
                #define NG_NETFLOW_CONF_THISONCE        8
            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
            exactly this netflow node. Last two options are important to
            avoid duplicate accounting when both ingress and egress NetFlow
            are enabled.
            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;
                        uint16_t packets;
            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.
            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_settemtu {
                        uint16_t mtu;
            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.


    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 }"
    NGM_NETFLOW_SETCONFIG    "setconfig { iface = %u conf = %u }"
    NGM_NETFLOW_SETTEMPLATE  "settemplate { time = %u packets = %u }"
    NGM_NETFLOW_SETMTU       "setmtu { mtu = %u }"

[править] SHUTDOWN

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

[править] 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/
    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 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/

[править] SEE ALSO

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.

[править] AUTHORS

    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 <>.

[править] BUGS

    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.

FreeBSD 9.0 March 2, 2011 FreeBSD 9.0


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