Content-type: text/html Manpage of stak


Section: User Commands (1)
Updated: 21-March-2004
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stak - Statistical Traffic Analysis Kit  


stakrate [generic options] [rate-estimator-specific options]

stakhosts [generic options] [host-statistics-specific options]

stakasta [generic options] [as-traffic-analyzer-specific options]

stakextract [generic options] [regex-extractor-specific options]

stakstreams [generic options] [stream-analyzer-specific options]


stak helps an administrator to figure out what is happening in his network at the moment. Unlike tcpdump(1), stak uses statistical and stream-oriented traffic analysing methods, and it will never produce an output stream at a speed beyond human perception. The output is less accurate, however.

stak consists of five different utilities, designed to perform the following tasks:

estimating overall traffic rates (stakrate)

determining nodes generating the highest traffic (stakhosts)

determining connections and flows generating the highest traffic (stakstreams)

extracting strings from packets (stakextract)

estimating traffic exchange with particular autonomous systems (stakasta)

All the utilities share a generic sniffer framework, based on the pcap(3) library.



Each of the utilities accepts parameters in a standard, short getopt(3) syntax. There are several options concerning the sniffer framework, common for the all stak utilities - these options are described below in this manual.

After a successful startup, each of the utilities installs a packet capturing handler and starts to process data and generate reports. The default report generating policy is to dump a report to stdout every 100 milliseconds - you can adjust this time using the -r option, or choose a different report generation policy (on key stroke, or upon receiving a signal) by using the -g or -k options.

Each utility processes the captured data and presents the results in its very own way and thus has its very own set of specific options. You can find these on separate manual pages.

Always make sure stak has enough information on datalink layer protocol present on the interface it was ordered to bind to. Consult the -p option description for details.



-0 c
Replace every NUL character (ASCII 0) with c before doing regular expression based matching. Ignored if the -x option was not specified. The default is '@'.
Color (ANSI-compatible) output in modes that support it (currently: stream analyzer and "abusers detection" mode).
-f f
BPF filter expression to use. Using this option causes stak to ignore any packets not matching the specified BPF filter expression. For a detailed description of BPF filter expressions syntax, consult the tcpdump(1) manual page.
Signal-based report generation policy. The reports are dumped whenever stak receives a SIGUSR1 signal.
-h -?
Print help. stak dumps a short help on available command-line options and quits, regardless of other options.
-i I
Bind to interface I. The default is 'eth0', which of course will cause a failure on systems other than Linux. Make sure you specify the datalink prefix (see -p) when you order stak to bind to an interface of an uncommon type.
Interactive report generation. The reports are dumped whenever data is available on the standard input, which usually means you'll have to press RETURN in order to generate a report.
Make stdout line-buffered. This option is useful when reports are redirected (eg. using shell redirection) to a file.
Turns off asynchronous reverse DNS lookups. stak will print numeric IPs rather than fully qualified domain names.
-p N
Datalink layer header prefix length. Every (or at least almost every) known datalink layer protocol prefixes a packet with its own header - which has to be stripped before the actual data essential for stak (the IP protocol header) can be read. stak is able to determine automatically how many bytes to skip only for the most common datalink layer protocols (Ethernet, FDDI, TokenRing, loopback, PPP) - in other cases the prefix length must be specified using this option. It is EXTREMELY IMPORTANT to set the right value - otherwise stak might print completely irrevelant reports and output invalid IP addresses. The default is autosense, or if that fails - 14 bytes, which is the length of an Ethernet header.
-q N
Orders stak to quit after outputting N reports.
-r N
Time-based report generation policy. The reports will be dumped on stdout every N seconds. This is the default (with N = 0.1).
-s N
Capture at least N bytes. For performance reasons, stak does not acquire the whole packet from network, it just reads and processes first N bytes. The default is 64 bytes, which might be not enough if you are using complicated BPF expressions or filtering the packets using a regular expression. In such cases, it is good to set the capture length to MTU on the interface. The value is automatically increased to at least 1500 (which is the default MTU for an Ethernet interface) if one of -x, -E or -T options is used. This option does NOT affect statistical data (amount of bytes, per-second byte rate) collected by stak - the accounted packet size is always the 'real' one.

Print exact values. Normally, stak uses SI prefixes (like k - kilo, M - mega, G - giga, T - tera) to make the printed numeric values more attractive for a human being. The -v option disables this feature, causing stak to print exact values.
Clear the screen before printing each report. This assumes your terminal is capable of understanding certain control sequences.
-X r
Regular expression-based filtering. This option will cause stak to ignore packets that DO NOT match specified regular expression. Before any tests, NUL characters occuring in a packet are replaced with an other character, as specified in the -0 option (the default is '@'). Consult regex(5) manual for a detailed description of POSIX regular expressions. In addition to standard regex syntax, you may use the \r (CR), \n (LF), \t (TAB), \\ (\) and \xNN (hex NN) special sequences.



The TRAFFIC ANALYZER (-T) operation mode is experimental. It consumes large amounts of system resources. Memory leaks in code that provides this feature are possible.



stakrate(1), stakhosts(1), stakasta(1), stakstreams(1), stakextract(1), tcpdump(1), regex(7), pcap(3), bpf(4)



Mateusz Golicz <>

Feel free to send comments, suggestions, bug reports, etc. The author is not a native english speaker, and is aware of the fact that his english is far from perfect. Because of that, reports on grammar or vocabulary mistakes in this manual are also welcome.

The asynchronous DNS resolver part was taken from mtr - a very handy traceroute replacement by Matt Kimball.



Copyright 2003 - 2004 Mateusz Golicz. All rights reserved.

This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License, Version 2, as published by the Free Software Foundation. A copy of this license is distributed with this software in the file "COPYING".

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. Read the file "COPYING" for more details.




This document was created by man2html, using the manual pages.
Time: 14:58:33 GMT, March 21, 2004