table of contents
NG_NETFLOW(4) | Device Drivers Manual | NG_NETFLOW(4) |
NAME¶
ng_netflow — Cisco's NetFlow implementationSYNOPSIS¶
#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.
HOOKS¶
This node type supports up toNG_NETFLOW_MAXIFACES
hooks
named iface0, iface1, etc., and
the same number of hooks named out0,
out1, etc., plus a single hook named
export. By default (ingress NetFlow enabled) 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 (egress NetFlow
disabled by default). 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 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 */ };
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 */ };
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_SETCONFIG
- 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 };
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 }
” NGM_NETFLOW_SETCONFIG
- “
setconfig { iface = %u conf = %u }
”
SHUTDOWN¶
This node shuts down upon receipt of aNGM_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
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.htmAUTHORS¶
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 viaNGM_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.October 8, 2008 | Debian |