darkstat(1)

NAME
darkstat v3 - network statistics gatherer

SYNOPSIS
darkstat [ -i interface ] [ -r file ] [ --debug ] [ --no-promisc ] [ --no-dns ] [ -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 ]

DESCRIPTION
darkstat is a packet sniffer that runs as a background process on a cable/DSL router, 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.

--debug
    Debugging mode: do not detach from the controlling terminal, stay in the foreground instead.

--no-promisc
    Do not use promiscuous mode to capture. Note that an interface may already be in promiscuous mode. If this is a problem, use an appropriate bpf(4) filter.

--no-dns
    Do not resolve IPs to host names.

-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.

--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.

--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.

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"

(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

TROUBLESHOOTING
If you are using PPPoE (for example, on ADSL), and sniffing on an ethernet interface, you might see warnings about PPPoE packets:

    ether: unknown protocol (8864)

In order to get usable statistics, you need to sniff on the tunnel interface that your PPPoE software provides. For example:

    darkstat -i tun0

Or, on OpenBSD or NetBSD, sniff on the pppoe interface:

    darkstat -i pppoe0

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. If you want to account for all traffic entering or leaving a network, you can use the -l commandline argument.

SEE ALSO
tcpdump(1)

AUTHOR
Emil Mikulic, and others (see AUTHORS and THANKS).

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