darkstat - network statistics gatherer
[ -i interface
] [ -r file
] [ --pppoe
] [ --syslog
] [ --no-daemon
] [ --no-promisc
] [ --no-macs
] [ --no-lastseen
] [ -p
] [ -b bindaddr
] [ --base path
] [ -l network/netmask
] [ --chroot dir
] [ --user
] [ --daylog filename
] [ --import
] [ --export filename
] [ --pidfile
] [ --hosts-max count
] [ --hosts-keep
] [ --ports-max count
] [ --ports-keep
] [ --highest-port port
] [ --wait secs
] [ --hexdump
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.
- -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
- --snaplen bytes
- How many bytes to capture from the start of each packet.
You should not need to specify this; darkstat will calculate it
- Don't use this.
Instead, capture on the tunnel interface that your PPPoE software provides,
for example tun0 on FreeBSD, pppoe0 on OpenBSD
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
- 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
- Produce more verbose debugging messages.
- Do not detach from the controlling terminal; stay in the
- 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
- 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.
- Do not display MAC addresses in the hosts table.
- Do not display the last seen time in the hosts table.
- -p port
- Bind the web interface to the specified port. The default
- -b bindaddr
- Bind the web interface to the specified address. The
default is to listen on all interfaces.
- --base path
Specify the path of the base URL. This can be
useful if darkstat
is accessed via a reverse proxy.
For example, if you use Apache's mod_proxy
and want to avoid a
complicated setup with mod_proxy_html
header), just set the base path to something like
and use a config similar to the following snippet:
ProxyPass /stats/ http://localhost:667/stats/
ProxyPassReverse /stats/ http://localhost:667/stats/
The default is /
(i.e. the root).
- -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(8) 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.
- Make the web interface only display hosts on the
"local network." This is intended to be used together with the
- --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
For security reasons, this directory should be empty, and the user that
is running as should not have write access to it.
However, if you wish to use --daylog
will need write access to the chroot. If you are uncomfortable with the
security implications, don't use any functionality that requires write
- --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
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
If the daylog argument is not specified, no logging is performed.
The daylog format is:
Lines starting with a # are comments stating when logging started and
- --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
- --export filename
- On shutdown, or upon receiving SIGUSR1 or SIGUSR2, 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
- --pidfile filename
Creates a file containing the process ID of
. 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
- darkstat -i fxp0 --chroot /var/run/darkstat --pidfile
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 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 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
to the specified number of seconds for the interface to become ready. Zero
means wait indefinitely.
- Show hex dumps of received traffic. This is only for
debugging, and implies --verbose and --no-daemon.
To gather statistics on the fxp0
- 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
- 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
(For a full reference on filter syntax, refer to the tcpdump
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
- 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
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
To shut darkstat
down cleanly, send a SIGTERM or SIGINT signal to the
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. Sending SIGUSR2 will save the database without emptying it.
Hover your mouse cursor over a bar and you should get a tooltip saying exactly
how many bytes in and out the bar represents.
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.
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.
was written in 2001, largely as a result of a certain Australian
cable Internet provider introducing a 3GB monthly traffic limit.
Emil Mikulic and others. (see the AUTHORS file)