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<p><i>SOFTFLOWD</i>(8) System Manager&rsquo;s Manual
<i>SOFTFLOWD</i>(8)</p>

<p style="margin-top: 1em"><b>NAME</b></p>

<p style="margin-left:9%;">softflowd &mdash; Traffic flow
monitoring</p>

<p style="margin-top: 1em"><b>SYNOPSIS</b></p>

<p style="margin-left:22%;"><b>softflowd</b>
[<b>-6dDhbalN</b>] [<b>-L&nbsp;</b><i>hoplimit</i>]
[<b>-T&nbsp;</b><i>track_level</i>]
[<b>-c&nbsp;</b><i>ctl_sock</i>] [</p>

<p><b>-i&nbsp;</b> [ <i><br>
if_ndx</i>:]<i>interface</i> ]
[<b>-m&nbsp;</b><i>max_flows</i>]
[<b>-n&nbsp;</b><i>host:port</i>]
[<b>-p&nbsp;</b><i>pidfile</i>]
[<b>-r&nbsp;</b><i>pcap_file</i>]
[<b>-t&nbsp;</b><i>timeout_name=seconds</i>]
[<b>-v&nbsp;</b><i>netflow_version</i>]
[<b>-P&nbsp;</b><i>transport_protocol</i>]
[<b>-A&nbsp;</b><i>time_format</i>]
[<b>-s&nbsp;</b><i>sampling_rate</i>]
[<b>-C&nbsp;</b><i>capture_length</i>]
[<b>-R&nbsp;</b><i>receive_port</i>]
[<b>-S&nbsp;</b><i>send_interface_name</i>]
[<b>-x&nbsp;</b><i>number_of_mpls_labels</i>]
[<b>-e&nbsp;</b><i>exporter_ip_address</i>]
[bpf_expression]</p>

<p style="margin-top: 1em"><b>DESCRIPTION</b></p>

<p style="margin-left:9%;"><b>softflowd</b> is a software
implementation of a flow-based network traffic monitor.
<b>softflowd</b> reads network traffic and gathers
information about active traffic flows. A &quot;traffic
flow&quot; is communication between two IP addresses or (if
the overlying protocol is TCP or UDP) address/port
tuples.</p>

<p style="margin-left:9%; margin-top: 1em">The intended use
of <b>softflowd</b> is as a software implementation of
Cisco&rsquo;s NetFlow(tm) traffic account system.
<b>softflowd</b> supports data export using versions 1, 5, 9
or 10 (a.k.a. IPFIX) of the NetFlow protocol.
<b>softflowd</b> can also run in statistics-only mode, where
it just collects summary information. However, too few
statistics are collected to make this mode really useful for
anything other than debugging.</p>

<p style="margin-left:9%; margin-top: 1em">Network traffic
may be obtained by listening on a promiscuous network
interface (unless the <b>-N</b> option is given) or by
reading stored <i>pcap</i>(3) files, such as those written
by <i>tcpdump</i>(8). Traffic may be filtered with an
optional <i>bpf</i>(4) program, specified on the
command-line as <i>bpf_expression</i>. <b>softflowd</b> is
IPv6 capable and will track IPv6 flows if the NetFlow export
protocol supports it (currently only NetFlow v.9 possesses
an IPv6 export capability).</p>


<p style="margin-left:9%; margin-top: 1em"><b>softflowd</b>
tries to track only active traffic flows. When the flow has
been quiescent for a period of time it is expired
automatically. Flows may also be expired early if they
approach their traffic counts exceed 2 Gib or if the number
of flows being tracked exceeds <i>max_flows</i> (default:
8192). In this last case, flows are expired
oldest-first.</p>

<p style="margin-left:9%; margin-top: 1em">Upon expiry, the
flow information is accumulated into statistics which may be
viewed using <i>softflowctl</i>(8). If the <b>-n</b> option
has been specified the flow information is formatted in a
UDP datagram which is compatible with versions 1, 5 or 9 of
Cisco&rsquo;s NetFlow(tm) accounting export format. These
records are sent to the specified <i>host</i> and
<i>port</i>. The host may represent a unicast host or a
multicast group.</p>

<p style="margin-left:9%; margin-top: 1em">The command-line
options are as follows:</p>

<p style="margin-top: 1em"><b>-n</b> <i>host:port</i></p>

<p style="margin-left:19%;">Specify the <i>host</i> and
<i>port</i> that the accounting datagrams are to be sent to.
The host may be specified using a hostname or using a
numeric IPv4 or IPv6 address. Numeric IPv6 addresses should
be enclosed in square brackets to avoid ambiguity between
the address and the port. The destination port may be a
portname listed in <i>services</i>(5) or a numeric port.
Comma can be used for specifying multiple destinations.</p>

<p style="margin-top: 1em"><b>-N</b></p>

<p style="margin-left:19%; margin-top: 1em">Do not put the
interface into promiscuous mode. Note that the interface
might be in promiscuous mode for some other reason.</p>

<p style="margin-top: 1em"><b>-i</b> <br>
[ <i><br>
if_ndx</i>:]<i>interface</i></p>

<p style="margin-left:19%;">Specify a network interface on
which to listen for traffic. Either the <b>-i</b> or the
<b>-r</b> options must be specified.</p>

<p style="margin-top: 1em"><b>-r</b> <i>pcap_file</i></p>

<p style="margin-left:19%;">Specify that <b>softflowd</b>
should read from a <i>pcap</i>(3) packet capture file (such
as one created with the <b>-w</b> option of
<i>tcpdump</i>(8)) file rather than a network interface.
<b>softflowd</b> processes the whole capture file and only
expires flows when <i>max_flows</i> is exceeded. In this
mode, <b>softflowd</b> will not fork and will automatically
print summary statistics before exiting.</p>

<p style="margin-top: 1em"><b>-p</b> <i>pidfile</i></p>

<p style="margin-left:19%;">Specify an alternate location
to store the process ID when in daemon mode. Default is
<i>/var/run/softflowd.pid</i></p>

<p style="margin-top: 1em"><b>-c</b> <i>ctlsock</i></p>

<p style="margin-left:19%;">Specify an alternate location
for the remote control socket in daemon mode. Default is
<i>/var/run/softflowd.ctl</i></p>

<p style="margin-top: 1em"><b>-m</b> <i>max_flows</i></p>

<p style="margin-left:19%;">Specify the maximum number of
flows to concurrently track. If this limit is exceeded, the
flows which have least recently seen traffic are forcibly
expired. In practice, the actual maximum may briefly exceed
this limit by a small amount as expiry processing happens
less frequently than traffic collection. The default is 8192
flows, which corresponds to slightly less than 800k of
working data.</p>

<p style="margin-top: 1em"><b>-t</b>
<i>timeout_name=time</i></p>

<p style="margin-left:19%;">Set the timeout names
<i>timeout_name</i> to <i>time</i>. Refer to the
&ldquo;Timeouts&rdquo; section for the valid timeout names
and their meanings. The <i>time</i> parameter may be
specified using one of the formats explained in the
&ldquo;Time Formats&rdquo; section below.</p>

<p style="margin-top: 1em"><b>-d</b></p>

<p style="margin-left:19%; margin-top: 1em">Specify that
<b>softflowd</b> should not fork and daemonise itself.</p>

<p style="margin-top: 1em"><b>-6</b></p>

<p style="margin-left:19%; margin-top: 1em">Force
<b>softflowd</b> to track IPv6 flows even if the NetFlow
export protocol does not support reporting them. This is
useful for debugging and statistics gathering only.</p>

<p style="margin-top: 1em"><b>-D</b></p>

<p style="margin-left:19%; margin-top: 1em">Places
<b>softflowd</b> in a debugging mode. This implies the
<b>-d</b> and <b>-6</b> flags and turns on additional
debugging output.</p>

<p style="margin-top: 1em"><b>-B</b> <i>size_bytes</i></p>

<p style="margin-left:19%;">Libpcap buffer size in
bytes</p>

<p style="margin-top: 1em"><b>-b</b></p>

<p style="margin-left:19%; margin-top: 1em">Bidirectional
mode in IPFIX (-b work with -v 10)</p>

<p style="margin-top: 1em"><b>-a</b></p>

<p style="margin-left:19%; margin-top: 1em">Adjusting time
for reading pcap file (-a work with -r)</p>

<p style="margin-top: 1em"><b>-l</b></p>

<p style="margin-left:19%; margin-top: 1em">Load balancing
mode for multiple destinations which are specified with
-n</p>

<p style="margin-top: 1em"><b>-x</b>
<i>number_of_mpls_labels</i></p>

<p style="margin-left:19%;">specify number of mpls labels
for export</p>

<p style="margin-top: 1em"><b>-h</b></p>

<p style="margin-left:19%; margin-top: 1em">Display
command-line usage information.</p>

<p style="margin-top: 1em"><b>-L</b> <i>hoplimit</i></p>

<p style="margin-left:19%;">Set the IPv4 TTL or the IPv6
hop limit to <i>hoplimit</i>. <b>softflowd</b> will use the
default system TTL when exporting flows to a unicast host.
When exporting to a multicast group, the default TTL will be
1 (i.e. link-local).</p>

<p style="margin-top: 1em"><b>-T</b> <i>track_level</i></p>

<p style="margin-left:19%;">Specify which flow elements
<b>softflowd</b> should be used to define a flow.
<i>track_level</i> may be one of: &ldquo;ether&rdquo; (track
everything including source and destination addresses,
source and destination port, source and destination ethernet
address, vlanid and protocol), &ldquo;vlan&rdquo; (track
source and destination addresses, source and destination
port, vlanid and protocol), &ldquo;full&rdquo; (track source
and destination addresses, source and destination port and
protocol in the flow, the default), &ldquo;proto&rdquo;
(track source and destination addresses and protocol), or
&ldquo;ip&rdquo; (only track source and destination
addresses). Selecting either of the latter options will
produce flows with less information in them (e.g. TCP/UDP
ports will not be recorded). This will cause flows to be
consolidated, reducing the quantity of output and CPU load
that <b>softflowd</b> will place on the system at the cost
of some detail being lost.</p>

<p style="margin-top: 1em"><b>-v</b>
<i>netflow_version</i></p>

<p style="margin-left:19%;">Specify which version of the
NetFlow(tm) protocol <b>softflowd</b> should use for export
of the flow data. Supported versions are 1, 5, 9, 10(IPFIX),
and psamp. Default is version 5.</p>

<p style="margin-top: 1em"><b>-P</b>
<i>transport_protocol</i></p>

<p style="margin-left:19%;">Specify transport layer
protocol for exporting packets. Supported transport layer
protocols are udp, tcp, and sctp.</p>

<p style="margin-top: 1em"><b>-A</b> <i>time_format</i></p>

<p style="margin-left:19%;">Specify absolute time format
form exporting records. Supported time formats are sec,
milli, micro, and nano.</p>

<p style="margin-top: 1em"><b>-s</b>
<i>sampling_rate</i></p>

<p style="margin-left:19%;">Specify periodical sampling
rate (denominator).</p>

<p style="margin-top: 1em"><b>-C</b>
<i>capture_length</i></p>

<p style="margin-left:19%;">Specify length for packet
capture (snaplen).</p>

<p style="margin-top: 1em"><b>-R</b>
<i>receive_port</i></p>

<p style="margin-left:19%;">Specify port number for PSAMP
receive mode.</p>

<p style="margin-top: 1em"><b>-S</b>
<i>send_interface_name</i></p>

<p style="margin-left:19%;">Specify send interface name.
(This option works on Linux only because of use of
SO_BINDTODEVICE for setsockopt.)</p>

<p style="margin-top: 1em"><b>-e</b>
<i>exporter_ip_address</i></p>

<p style="margin-left:19%;">Specify exporter IPv4 or IPv6
address.</p>

<p style="margin-left:9%; margin-top: 1em">Any further
command-line arguments will be concatenated together and
applied as a <i>bpf</i>(4) packet filter. This filter will
cause <b>softflowd</b> to ignore the specified traffic.</p>


<p style="margin-left:4%; margin-top: 1em"><b>Timeouts</b></p>

<p style="margin-left:9%;"><b>softflowd</b> will expire
quiescent flows after user-configurable periods. The exact
timeout used depends on the nature of the flow. The various
timeouts that may be set from the command-line (using the
<b>-t</b> option) and their meanings are:</p>

<p style="margin-top: 1em"><i>general</i></p>

<p style="margin-left:19%;">This is the general timeout
applied to all traffic unless overridden by one of the other
timeouts.</p>

<p style="margin-top: 1em"><i>tcp</i></p>

<p style="margin-left:19%; margin-top: 1em">This is the
general TCP timeout, applied to open TCP connections.</p>

<p style="margin-top: 1em"><i>tcp.rst</i></p>

<p style="margin-left:19%;">This timeout is applied to a
TCP connection when a RST packet has been sent by one or
both endpoints.</p>

<p style="margin-top: 1em"><i>tcp.fin</i></p>

<p style="margin-left:19%;">This timeout is applied to a
TCP connection when a FIN packet has been sent by both
endpoints.</p>

<p style="margin-top: 1em"><i>udp</i></p>

<p style="margin-left:19%; margin-top: 1em">This is the
general UDP timeout, applied to all UDP connections.</p>

<p style="margin-top: 1em"><i>maxlife</i></p>

<p style="margin-left:19%;">This is the maximum lifetime
that a flow may exist for. All flows are forcibly expired
when they pass <i>maxlife</i> seconds. To disable this
feature, specify a <i>maxlife</i> of 0.</p>

<p style="margin-top: 1em"><i>expint</i></p>

<p style="margin-left:19%; margin-top: 1em">Specify the
interval between expiry checks. Increase this to group more
flows into a NetFlow packet. To disable this feature,
specify a <i>expint</i> of 0.</p>

<p style="margin-left:9%; margin-top: 1em">Flows may also
be expired if there are not enough flow entries to hold them
or if their traffic exceeds 2 Gib in either direction.
<i>softflowctl</i>(8) may be used to print information on
the average lifetimes of flows and the reasons for their
expiry.</p>

<p style="margin-left:4%; margin-top: 1em"><b>Time
Formats</b></p>

<p style="margin-left:9%;"><b>softflowd</b> command-line
arguments that specify time may be expressed using a
sequence of the form: <i>time</i>[<i>qualifier</i>], where
<i>time</i> is a positive integer value and <i>qualifier</i>
is one of the following:</p>

<p style="margin-top: 1em"><b>&lt;none&gt;</b></p>

<p style="margin-left:27%; margin-top: 1em">seconds</p>

<p><b>s</b> | <b>S</b></p>

<p style="margin-left:27%; margin-top: 1em">seconds</p>

<p><b>m</b> | <b>M</b></p>

<p style="margin-left:27%; margin-top: 1em">minutes</p>

<p><b>h</b> | <b>H</b></p>

<p style="margin-left:27%; margin-top: 1em">hours</p>

<p><b>d</b> | <b>D</b></p>

<p style="margin-left:27%; margin-top: 1em">days</p>

<p><b>w</b> | <b>W</b></p>

<p style="margin-left:27%; margin-top: 1em">weeks</p>

<p style="margin-left:9%; margin-top: 1em">Each member of
the sequence is added together to calculate the total time
value.</p>

<p style="margin-left:9%; margin-top: 1em">Time format
examples:</p>

<p style="margin-top: 1em">600</p>

<p style="margin-left:27%; margin-top: 1em">600 seconds (10
minutes)</p>

<p>10m</p>

<p style="margin-left:27%; margin-top: 1em">10 minutes</p>

<p>1h30m</p>

<p style="margin-left:27%; margin-top: 1em">1 hour 30
minutes (90 minutes)</p>

<p style="margin-left:4%; margin-top: 1em"><b>Run-time
Control</b></p>

<p style="margin-left:9%;">A daemonised <b>softflowd</b>
instance may be controlled using the <i>softflowctl</i>(8)
command. This interface allows one to shut down the daemon,
force expiry of all tracked flows and extract debugging and
summary data. Also, receipt of a SIGTERM or SIGINT will
cause <b>softflowd</b> to exit, after expiring all flows
(and thus sending flow export packets if <b>-n</b> was
specified on the command-line). If you do not want to export
flows upon shutdown, clear them first with
<i>softflowctl</i>(8) or use <i>softflowctl</i>(8) &rsquo;s
&ldquo;exit&rdquo; command.</p>

<p style="margin-top: 1em"><b>EXAMPLES</b> <br>
softflowd -i fxp0</p>

<p style="margin-left:19%;">This command-line will cause
<b>softflowd</b> to listen on interface fxp0 and to run in
statistics gathering mode only (i.e. no NetFlow data
export).</p>

<p style="margin-top: 1em">softflowd -i fxp0 -n
10.1.0.2:4432</p>

<p style="margin-left:19%;">This command-line will cause
<b>softflowd</b> to listen on interface fxp0 and to export
NetFlow v.5 datagrams on flow expiry to a flow collector
running on 10.1.0.2 port 4432.</p>

<p style="margin-top: 1em">softflowd -i fxp0 -n
10.1.0.2:4432,10.1.0.3:4432</p>

<p style="margin-left:19%;">This command-line will cause
<b>softflowd</b> to listen on interface fxp0 and to export
NetFlow v.5 datagrams on flow expiry to a flow collector
running on 10.1.0.2 port 4432 and 10.1.0.3 port 4432.</p>

<p style="margin-top: 1em">softflowd -i fxp0 -l -n
10.1.0.2:4432,10.1.0.3:4432</p>

<p style="margin-left:19%;">This command-line will cause
<b>softflowd</b> to listen on interface fxp0 and to export
NetFlow v.5 datagrams on flow expiry to a flow collector
running on 10.1.0.2 port 4432 and 10.1.0.3 port 4432 with
load balncing mode. Odd netflow packets will be sent to
10.1.0.2 port 4432 and even netflow packets will be sent to
10.1.0.3 port 4432.</p>

<p style="margin-top: 1em">softflowd -v 5 -i fxp0 -n
10.1.0.2:4432 -m 65536 -t udp=1m30s</p>

<p style="margin-left:19%;">This command-line increases the
number of concurrent flows that <b>softflowd</b> will track
to 65536 and increases the timeout for UDP flows to 90
seconds.</p>

<p style="margin-top: 1em">softflowd -v 9 -i fxp0 -n
224.0.1.20:4432 -L 64</p>

<p style="margin-left:19%;">This command-line will export
NetFlow v.9 flows to the multicast group 224.0.1.20. The
export datagrams will have their TTL set to 64, so multicast
receivers can be many hops away.</p>

<p style="margin-top: 1em">softflowd -i fxp0 -p
/var/run/sfd.pid.fxp0 -c /var/run/sfd.ctl.fxp0</p>

<p style="margin-left:19%;">This command-line specifies
alternate locations for the control socket and pid file.
Similar command-lines are useful when running multiple
instances of <b>softflowd</b> on a single machine.</p>

<p style="margin-top: 1em"><b>FILES</b> <i><br>
/var/run/softflowd.pid</i></p>

<p style="margin-left:19%;">This file stores the process ID
when <b>softflowd</b> is in daemon mode. This location may
be overridden using the <b>-p</b> command-line option.</p>


<p style="margin-top: 1em"><i>/var/run/softflowd.ctl</i></p>

<p style="margin-left:19%;">This is the remote control
socket. <b>softflowd</b> listens on this socket for commands
from <i>softflowctl</i>(8). This location may be overridden
using the <b>-c</b> command-line option.</p>

<p style="margin-top: 1em"><b>BUGS</b></p>

<p style="margin-left:9%;">Currently <b>softflowd</b> does
not handle maliciously fragmented packets properly, i.e.
packets fragemented such that the UDP or TCP header does not
fit into the first fragment. It will product correct traffic
counts when presented with maliciously fragmented packets,
but will not record TCP or UDP port information. Please
report bugs in softflowd to
https://github.com/irino/softflowd/issues</p>

<p style="margin-top: 1em"><b>AUTHORS</b></p>

<p style="margin-left:9%;">Damien Miller
&lt;djm@mindrot.org&gt; <br>
Hitoshi Irino (current maintainer)
&lt;irino@sfc.wide.ad.jp&gt;</p>

<p style="margin-top: 1em"><b>SEE ALSO</b></p>

<p style="margin-left:9%;"><i>softflowctl</i>(8),
<i>tcpdump</i>(8), <i>pcap</i>(3), <i>bpf</i>(4)</p>


<p style="margin-left:9%; margin-top: 1em">http://www.ietf.org/rfc/rfc3954.txt
<br>

http://www.cisco.com/en/US/products/sw/netmgtsw/ps1964/products_implementation_design_guide09186a00800d6a11.html
<br>
http://www.ietf.org/rfc/rfc5101.txt <br>
http://www.ietf.org/rfc/rfc5103.txt Debian November 17, 2019
<i>SOFTFLOWD</i>(8)</p>
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