darkstat(8)                                                        darkstat(8)



NAME
       darkstat - network statistics gatherer

SYNOPSIS
       darkstat [ -i interface ] [ -r file ] [ --snaplen bytes ] [ --pppoe ] [
       --syslog ] [ --verbose ] [ --no-daemon ] [ --no-promisc ] [ --no-dns ]
       [ --no-macs ] [ --no-lastseen ] [ -p port ] [ -b bindaddr ] [ -f filter
       ] [ -l network/netmask ] [ --chroot dir ] [ --user username ] [
       --daylog filename ] [ --import filename ] [ --export filename ] [
       --pidfile filename ] [ --hosts-max count ] [ --hosts-keep count ] [
       --ports-max count ] [ --ports-keep count ] [ --highest-port port ] [
       --wait secs ] [ --hexdump ]

DESCRIPTION
       darkstat is a packet sniffer that runs as a background process, gathers
       all sorts of statistics about network usage, and serves them over HTTP.

       All settings are passed on the commandline.

OPTIONS
       -i interface
              Capture traffic on the specified network interface.  This is the
              only mandatory commandline argument.

       -r file
              Instead of capturing live traffic, read it from a pcap(3)
              capture file.  This is only useful for development and
              benchmarking.  The -r and -i arguments are mutually exclusive.

       --snaplen bytes
              How many bytes to capture from the start of each packet.  You
              should not need to specify this; darkstat will calculate it
              automatically.

       --pppoe
              Don't use this.

              Instead, capture on the tunnel interface that your PPPoE
              software provides, for example tun0 on FreeBSD, pppoe0 on
              OpenBSD or NetBSD.

              If you really must, you can capture on an Ethernet interface and
              pass this argument to have darkstat decode PPPoE frames and
              ignore everything else.  Make sure you also specify your local
              address with the -l argument!

       --syslog
              Errors, warnings, and verbose messages will go to syslog
              (facility daemon, priority debug) instead of stderr.

              On some systems, these messages end up in /var/log/debug by
              default. On OpenBSD, these messages end up in /var/log/daemon by
              default.

       --verbose
              Produce more verbose debugging messages.

       --no-daemon
              Do not detach from the controlling terminal; stay in the
              foreground.

       --no-promisc
              Do not use promiscuous mode to capture.  Note that an interface
              may already be in promiscuous mode, or may later enter
              promiscuous mode, due to circumstances beyond darkstat's
              control.  If this is a problem, use -f to specify an appropriate
              bpf(4) filter.

       --no-dns
              Do not resolve IPs to host names.  This can significantly reduce
              memory footprint on small systems as an extra process is created
              for DNS resolution.

       --no-macs
              Do not display MAC addresses in the hosts table.

       --no-lastseen
              Do not display the last seen time in the hosts table.

       -p port
              Bind the web interface to the specified port.  The default is
              667.

       -b bindaddr
              Bind the web interface to the specified address.  The default is
              to listen on all interfaces.

       -f filter
              Use the specified filter expression when capturing traffic.  The
              filter syntax is beyond the scope of this manual page; please
              refer to the tcpdump(1) documentation.

       -l network/netmask
              Define a "local network" according to the network and netmask
              addresses.  All traffic entering or leaving this network will be
              graphed, as opposed to the default behaviour of only graphing
              traffic to and from the local host.

              The rule is that if ip_addr & netmask == network, then that
              address is considered local.  See the usage example below.

       --chroot dir
              Force darkstat to chroot() into the specified directory.
              Without this argument, a default directory will be used, which
              is determined at build time.  Usually /var/empty or
              /var/lib/empty.

              For security reasons, this directory should be empty, and the
              user that darkstat is running as should not have write access to
              it.

              However, if you wish to use --daylog or --export, darkstat will
              need write access to the chroot.  If you are uncomfortable with
              the security implications, don't use any functionality that
              requires write access.

       --user username
              Force darkstat to drop privileges to the uid and gid of the
              specified user.  Without this argument, a default value will be
              used, which is set at build time.  Usually nobody.

              For security reasons, this should not be root.

       --daylog filename
              Log daily traffic statistics into the named file, relative to
              the chroot directory.  If you wish to use --daylog, you must
              first specify a --chroot directory, and it must be writeable by
              the darkstat user.  A writeable chroot has security
              implications; if you are uncomfortable with this, do not use the
              --daylog functionality.

              If the daylog argument is not specified, no logging is
              performed.

              The daylog format is:

              localtime|time_t|bytes_in|bytes_out|pkts_in|pkts_outs

              Lines starting with a # are comments stating when logging
              started and stopped.

       --import filename
              Upon starting, import a darkstat database from the named file,
              relative to the chroot directory.  If you wish to use --import,
              you must first specify a --chroot directory.  If the import is
              unsuccessful, darkstat will start with an empty database.

       --export filename
              On shutdown, and upon receiving SIGUSR1, export the in-memory
              database to the named file, relative to the chroot directory.
              If you wish to use --export, you must first specify a --chroot
              directory, and it must be writeable by the darkstat user.  A
              writeable chroot has security implications - if you are
              uncomfortable with this, do not use the --export functionality.

       --pidfile filename
              Creates a file containing the process ID of darkstat.  This file
              will be unlinked upon clean shutdown.  As with all pidfiles, if
              darkstat dies uncleanly, a stale pidfile can be left over.

              For example, start darkstat with:

                     darkstat -i fxp0 --chroot /var/run/darkstat --pidfile
                     darkstat.pid

              And stop with:

                     kill `cat /var/run/darkstat/darkstat.pid`

              By default, kill(1) will send SIGTERM, which will cause darkstat
              to shut down cleanly.

       --hosts-max count
              The maximum number of hosts that will be kept in the hosts
              table.  This is used to limit how much accounting data will be
              kept in memory.  The number of --hosts-max must be greater than
              --hosts-keep

       --hosts-keep count
              When the hosts table hits --hosts-max and traffic is seen from a
              new host, we clean out the hosts table, keeping only the top
              --hosts-keep number of hosts, sorted by total traffic.

       --ports-max count
              The maximum number of ports that will be tracked for each host.
              This is used to limit how much accounting data will be kept in
              memory.  The number of --ports-max must be greater than
              --ports-keep

       --ports-keep count
              When a ports table fills up, this many ports are kept and the
              rest are discarded.

       --highest-port port
              Ports that are numerically higher than this will not appear in
              the per-host ports tables, although their traffic will still be
              accounted for.  This can be used to hide ephemeral ports.  By
              default, all ports are tracked.

       --wait secs
              Don't use this.  It's a hack to help victims of NetworkManager
              and similar systems.

              You should start darkstat after the capture interface has come
              up.  If you can't, specifying the --wait option will make
              darkstat sleep up to the specified number of seconds for the
              interface to become ready.  Zero means wait indefinitely.

       --hexdump
              Show hex dumps of received traffic.  This is only for debugging,
              and implies --verbose and --no-daemon.

USAGE EXAMPLES
       To gather statistics on the fxp0 interface:

              darkstat -i fxp0

       We want to account for traffic on the Internet-facing interface, but
       only serve web pages to our private local network where we have the IP
       address 192.168.0.1:

              darkstat -i fxp0 -b 192.168.0.1

       We want to serve web pages on the standard HTTP port:

              darkstat -i fxp0 -p 80

       We are on Optus (cable) and don't want to account for the constant ARP
       traffic we are receiving:

              darkstat -i fxp0 -f "not arp"

       We only want to account for SSH traffic:

              darkstat -i fxp0 -f "port 22"

       We don't want to account for traffic between internal IPs:

              darkstat -i fxp0 -f "not (src net 192.168.0 and dst net
              192.168.0)"

       (For a full reference on filter syntax, refer to the tcpdump(1)
       manpage)

       We have a network consisting of a gateway server (192.168.1.1) and a
       few workstations (192.168.1.2, 192.168.1.3, etc.) and we want to graph
       all traffic entering and leaving the local network, not just the
       gateway server (which is running darkstat):

              darkstat -i fxp0 -l 192.168.1.0/255.255.255.0

       On some systems, we can't capture on a "decoded" interface but only on
       nas0 which returns PPPoE encapsulated packets.  Do PPPoE decoding, and
       override the local IP manually since it cannot be automatically
       detected.  Note the /32 netmask:

              darkstat -i nas0 --pppoe -l 192.168.1.1/255.255.255.255

SIGNALS
       To shut darkstat down cleanly, send a SIGTERM or SIGINT signal to the
       darkstat parent process.

       Sending the SIGUSR1 signal will cause darkstat to empty out its in-
       memory database.  If an --export file was set, it will first save the
       database to file.

FREQUENTLY ASKED QUESTIONS
   How many bytes does each bar on the graph represent?
       Hover your mouse cursor over a bar and you should get a tooltip saying
       exactly how many bytes in and out the bar represents.

   Why aren't there labels / tics / a scale on the graphs?
       Because implementing them is hard.  And doing so correctly, and in a
       way that works across all browsers, looks pretty much impossible.

       I might attempt it some day.  In the meantime, patches would be gladly
       accepted.

   Why are the graphs blank? All the bars are zero.
       The graphs only show traffic in/out of the local host, which is
       determined by getting the IP address of the interface you're sniffing
       on.

       You can use the -l argument to override the local address for
       accounting purposes.  You can also use it to do accounting for a whole
       subnet by specifying an appropriate netmask.

SEE ALSO
       tcpdump(1)

HISTORY
       darkstat was written in 2001, largely as a result of a certain
       Australian cable Internet provider introducing a 3GB monthly traffic
       limit.

AUTHORS
       Emil Mikulic and others. (see the AUTHORS file)

WEBSITE
       http://dmr.ath.cx/net/darkstat/



darkstat 3.0.713                  March 2010                       darkstat(8)
