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darkstat(8) System Manager's Manual 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 ] [ --base path ] [ -f filter ] [ -l network/netmask ] [ --local-only ] [ --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) cap- ture file. This is only useful for development and benchmark- ing. 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 au- tomatically. --pppoe Don't use this. Instead, capture on the tunnel interface that your PPPoE soft- ware 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 ig- nore everything else. Make sure you also specify your local ad- dress with the -l argument! --syslog Errors, warnings, and verbose messages will go to syslog (facil- ity daemon, priority debug) instead of stderr. On some systems, these messages end up in /var/log/debug by de- fault. --verbose Produce more verbose debugging messages. --no-daemon Do not detach from the controlling terminal; stay in the fore- ground. --no-promisc Do not use promiscuous mode to capture. Note that an interface may already be in promiscuous mode, or may later enter promiscu- ous mode, due to circumstances beyond darkstat's control. If this is a problem, use -f to specify an appropriate bpf(4) fil- ter. --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. --base path Specify the path of the base URL. This can be useful if dark- stat 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 (and mod_header to unset the Accept-Encoding header), just set the base path to something like stats 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(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 ad- dress is considered local. See the usage example below. --local-only Make the web interface only display hosts on the "local net- work." This is intended to be used together with the -l argu- ment. --chroot dir Force darkstat to chroot() into the specified directory. With- out 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 re- quires 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 implica- tions; if you are uncomfortable with this, do not use the --day- log functionality. If the daylog argument is not specified, no logging is per- formed. 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, or upon receiving SIGUSR1 or SIGUSR2, export the in-memory database to the named file, relative to the chroot di- rectory. 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 ta- ble. 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 dark- stat sleep up to the specified number of seconds for the inter- face 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) man- page) 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 gate- way 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 de- tected. 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-mem- ory database. If an --export file was set, it will first save the database to file. Sending SIGUSR2 will save the database without emp- tying it. 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 deter- mined by getting the IP address of the interface you're sniffing on. You can use the -l argument to override the local address for account- ing 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 Aus- tralian cable Internet provider introducing a 3GB monthly traffic limit. AUTHORS Emil Mikulic and others. (see the AUTHORS file) WEBSITE https://unix4lyfe.org/darkstat/ darkstat 3.0.721 June 2011 darkstat(8)
NAME | SYNOPSIS | DESCRIPTION | OPTIONS | USAGE EXAMPLES | SIGNALS | FREQUENTLY ASKED QUESTIONS | SEE ALSO | HISTORY | AUTHORS | WEBSITE
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