.\" Copyright (c) 2002 Damien Miller. All rights reserved. .\" Portions Copyright (c) 2001 Kevin Steves. All rights reserved. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. .\" .\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR .\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES .\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. .\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, .\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT .\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, .\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY .\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. .\" .Dd November 17, 2019 .Dt SOFTFLOWD 8 .Os .Sh NAME .Nm softflowd .Nd Traffic flow monitoring .Sh SYNOPSIS .Nm softflowd .Op Fl 6dDhbalN .Op Fl L Ar hoplimit .Op Fl T Ar track_level .Op Fl c Ar ctl_sock .Bk -words .Oo Fl i\ \& .Sm off .Oo Ar if_ndx : Oc .Ar interface .Sm on .Oc .Ek .Op Fl m Ar max_flows .Op Fl n Ar host:port .Op Fl p Ar pidfile .Op Fl r Ar pcap_file .Op Fl t Ar timeout_name=seconds .Op Fl v Ar netflow_version .Op Fl P Ar transport_protocol .Op Fl A Ar time_format .Op Fl s Ar sampling_rate .Op Fl C Ar capture_length .Op Fl R Ar receive_port .Op Fl S Ar send_interface_name .Op Fl x Ar number_of_mpls_labels .Op bpf_expression .Sh DESCRIPTION .Nm is a software implementation of a flow-based network traffic monitor. .Nm reads network traffic and gathers information about active traffic flows. A "traffic flow" is communication between two IP addresses or (if the overlying protocol is TCP or UDP) address/port tuples. .Pp The intended use of .Nm is as a software implementation of Cisco's NetFlow(tm) traffic account system. .Nm supports data export using versions 1, 5, 9 or 10 (a.k.a. IPFIX) of the NetFlow protocol. .Nm 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. .Pp Network traffic may be obtained by listening on a promiscuous network interface (unless the .Fl N option is given) or by reading stored .Xr pcap 3 files, such as those written by .Xr tcpdump 8 . Traffic may be filtered with an optional .Xr bpf 4 program, specified on the command-line as .Ar bpf_expression . .Nm 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). .Pp .Nm 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 .Ar max_flows (default: 8192). In this last case, flows are expired oldest-first. .Pp Upon expiry, the flow information is accumulated into statistics which may be viewed using .Xr softflowctl 8 . If the .Fl n option has been specified the flow information is formatted in a UDP datagram which is compatible with versions 1, 5 or 9 of Cisco's NetFlow(tm) accounting export format. These records are sent to the specified .Ar host and .Ar port . The host may represent a unicast host or a multicast group. .Pp The command-line options are as follows: .Bl -tag -width Ds .It Fl n Ar host:port Specify the .Ar host and .Ar port 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 .Xr services 5 or a numeric port. Comma can be used for specifying multiple destinations. .It Fl N Do not put the interface into promiscuous mode. Note that the interface might be in promiscuous mode for some other reason. .It Fl i Xo .Sm off .Oo Ar if_ndx : Oc .Ar interface .Sm on .Xc Specify a network interface on which to listen for traffic. Either the .Fl i or the .Fl r options must be specified. .It Fl r Ar pcap_file Specify that .Nm should read from a .Xr pcap 3 packet capture file (such as one created with the .Fl w option of .Xr tcpdump 8 ) file rather than a network interface. .Nm processes the whole capture file and only expires flows when .Ar max_flows is exceeded. In this mode, .Nm will not fork and will automatically print summary statistics before exiting. .It Fl p Ar pidfile Specify an alternate location to store the process ID when in daemon mode. Default is .Pa /var/run/softflowd.pid .It Fl c Ar ctlsock Specify an alternate location for the remote control socket in daemon mode. Default is .Pa /var/run/softflowd.ctl .It Fl m Ar max_flows 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. .It Fl t Ar timeout_name=time Set the timeout names .Ar timeout_name to .Ar time . Refer to the .Sx Timeouts section for the valid timeout names and their meanings. The .Ar time parameter may be specified using one of the formats explained in the .Sx Time Formats section below. .It Fl d Specify that .Nm should not fork and daemonise itself. .It Fl 6 Force .Nm to track IPv6 flows even if the NetFlow export protocol does not support reporting them. This is useful for debugging and statistics gathering only. .It Fl D Places .Nm in a debugging mode. This implies the .Fl d and .Fl 6 flags and turns on additional debugging output. .It Fl B Ar size_bytes Libpcap buffer size in bytes .It Fl b Bidirectional mode in IPFIX (-b work with -v 10) .It Fl a Adjusting time for reading pcap file (-a work with -r) .It Fl l Load balancing mode for multiple destinations which are specified with -n .It Fl x Ar number_of_mpls_labels specify number of mpls labels for export .It Fl h Display command-line usage information. .It Fl L Ar hoplimit Set the IPv4 TTL or the IPv6 hop limit to .Ar hoplimit . .Nm 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). .It Fl T Ar track_level Specify which flow elements .Nm should be used to define a flow. .Ar track_level may be one of: .Dq ether (track everything including source and destination addresses, source and destination port, source and destination ethernet address, vlanid and protocol), .Dq vlan (track source and destination addresses, source and destination port, vlanid and protocol), .Dq full (track source and destination addresses, source and destination port and protocol in the flow, the default), .Dq proto (track source and destination addresses and protocol), or .Dq ip (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 .Nm will place on the system at the cost of some detail being lost. .It Fl v Ar netflow_version Specify which version of the NetFlow(tm) protocol .Nm should use for export of the flow data. Supported versions are 1, 5, 9, 10(IPFIX), and psamp. Default is version 5. .It Fl P Ar transport_protocol Specify transport layer protocol for exporting packets. Supported transport layer protocols are udp, tcp, and sctp. .It Fl A Ar time_format Specify absolute time format form exporting records. Supported time formats are sec, milli, micro, and nano. .It Fl s Ar sampling_rate Specify periodical sampling rate (denominator). .It Fl C Ar capture_length Specify length for packet capture (snaplen). .It Fl R Ar receive_port Specify port number for PSAMP receive mode. .It Fl S Ar send_interface_name Specify send interface name. (This option works on Linux only because of use of SO_BINDTODEVICE for setsockopt.) .El .Pp Any further command-line arguments will be concatenated together and applied as a .Xr bpf 4 packet filter. This filter will cause .Nm to ignore the specified traffic. .Ss Timeouts .Pp .Nm 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 .Fl t option) and their meanings are: .Bl -tag -width Ds .It Ar general This is the general timeout applied to all traffic unless overridden by one of the other timeouts. .It Ar tcp This is the general TCP timeout, applied to open TCP connections. .It Ar tcp.rst This timeout is applied to a TCP connection when a RST packet has been sent by one or both endpoints. .It Ar tcp.fin This timeout is applied to a TCP connection when a FIN packet has been sent by both endpoints. .It Ar udp This is the general UDP timeout, applied to all UDP connections. .It Ar maxlife This is the maximum lifetime that a flow may exist for. All flows are forcibly expired when they pass .Ar maxlife seconds. To disable this feature, specify a .Ar maxlife of 0. .It Ar expint Specify the interval between expiry checks. Increase this to group more flows into a NetFlow packet. To disable this feature, specify a .Ar expint of 0. .El .Pp 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. .Xr softflowctl 8 may be used to print information on the average lifetimes of flows and the reasons for their expiry. .Ss Time Formats .Pp .Nm command-line arguments that specify time may be expressed using a sequence of the form: .Sm off .Ar time Op Ar qualifier , .Sm on where .Ar time is a positive integer value and .Ar qualifier is one of the following: .Pp .Bl -tag -width Ds -compact -offset indent .It Cm seconds .It Cm s | Cm S seconds .It Cm m | Cm M minutes .It Cm h | Cm H hours .It Cm d | Cm D days .It Cm w | Cm W weeks .El .Pp Each member of the sequence is added together to calculate the total time value. .Pp Time format examples: .Pp .Bl -tag -width Ds -compact -offset indent .It 600 600 seconds (10 minutes) .It 10m 10 minutes .It 1h30m 1 hour 30 minutes (90 minutes) .El .Ss Run-time Control .Pp A daemonised .Nm instance may be controlled using the .Xr softflowctl 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 .Dv SIGTERM or .Dv SIGINT will cause .Nm to exit, after expiring all flows (and thus sending flow export packets if .Fl n was specified on the command-line). If you do not want to export flows upon shutdown, clear them first with .Xr softflowctl 8 or use .Xr softflowctl 8 's .Dq exit command. .Sh EXAMPLES .Bl -tag -width Ds .It softflowd -i fxp0 This command-line will cause .Nm to listen on interface fxp0 and to run in statistics gathering mode only (i.e. no NetFlow data export). .It softflowd -i fxp0 -n 10.1.0.2:4432 This command-line will cause .Nm 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. .It softflowd -i fxp0 -n 10.1.0.2:4432,10.1.0.3:4432 This command-line will cause .Nm 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. .It softflowd -i fxp0 -l -n 10.1.0.2:4432,10.1.0.3:4432 This command-line will cause .Nm 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. .It softflowd -v 5 -i fxp0 -n 10.1.0.2:4432 -m 65536 -t udp=1m30s This command-line increases the number of concurrent flows that .Nm will track to 65536 and increases the timeout for UDP flows to 90 seconds. .It softflowd -v 9 -i fxp0 -n 224.0.1.20:4432 -L 64 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. .It softflowd -i fxp0 -p /var/run/sfd.pid.fxp0 -c /var/run/sfd.ctl.fxp0 This command-line specifies alternate locations for the control socket and pid file. Similar command-lines are useful when running multiple instances of .Nm on a single machine. .El .Sh FILES .Bl -tag -width Ds .It Pa /var/run/softflowd.pid This file stores the process ID when .Nm is in daemon mode. This location may be overridden using the .Fl p command-line option. .It Pa /var/run/softflowd.ctl This is the remote control socket. .Nm listens on this socket for commands from .Xr softflowctl 8 . This location may be overridden using the .Fl c command-line option. .El .Sh BUGS Currently .Nm 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 .Sh AUTHORS .An Damien Miller Aq djm@mindrot.org .An Hitoshi Irino (current maintainer) Aq irino@sfc.wide.ad.jp .Sh SEE ALSO .Xr softflowctl 8 , .Xr tcpdump 8 , .Xr pcap 3 , .Xr bpf 4 .Bd -literal http://www.ietf.org/rfc/rfc3954.txt .br http://www.cisco.com/en/US/products/sw/netmgtsw/ps1964/products_implementation_design_guide09186a00800d6a11.html http://www.ietf.org/rfc/rfc5101.txt .br http://www.ietf.org/rfc/rfc5103.txt .br .Ed