Content-type: text/html Manpage of stakhosts


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


stakhosts [-i <interface>] [-p <prefix>] [-s <snarflen>] [-r <n> | -g | -k] [-q <n>] [-lcvjx] [-X <expression> [-0 <c>]] [-f <filtering expression>] [-byt] [-a <n>] [-A | -M] [-P | -B] [-O | -I] <class/mask> [<class/mask> [<class/mask> ...]]


stakhosts is a part of the Statistical Traffic Analysis Kit (STAK), which is a set of utilities designed to help an administrator to figure out what is happening in his network at the moment.

stakhosts determines the top ten (or other number of) hosts in the local network generating the highest traffic. Average or momentary, packet or byte and input or output traffic rates might be considered while composing the host list.



stakhosts accepts parameters in a standard, short getopt(3) form.

There are several options concerning the stak sniffer framework, common for the all stak utilities - these options have been described in the GENERIC OPTIONS section below.

The remaining options, described in the BANDWIDTH ABUSERS MODE SPECIFIC OPTIONS are stakhosts-specific and do not apply to other stak utilities.

In order to make stakhosts operate properly, it is necessary to specify IP classes that are considered the local net. Only hosts from these classes will appear on the report.

For instance, to print the top "bandwidth abusers" in, you could use:

# stakhosts -i eth5 -cr 1

             Momentary Rx    Momentary Tx      Average Rx      Average Tx

              Bps     pps |   Bps     pps |   Bps     pps |   Bps     pps 41.72k 37.81 | 30.40k 42.79 | 48.29k 47.17 | 17.28k 33.27 40.79k 31.84 | 1.14k 18.91 | 34.92k 26.32 | 1.02k 16.88 24.61k 42.79 | 19.99k 48.76 | 14.03k 24.83 | 10.80k 28.30 22.07k 53.73 | 15.41k 47.76 | 15.46k 42.70 | 14.43k 44.19 20.11k 15.92 | 0.00 0.00 | 10.04k 7.94 | 0.00 0.00 15.58k 12.94 | 59.70 1.00 | 14.40k 13.90 |754.22 2.98 14.49k 11.94 | 1.70k 14.93 | 10.79k 8.94 | 1.20k 9.93 14.33k 22.89 | 4.27k 24.88 | 9.92k 21.35 | 4.84k 25.32 13.61k 9.95 |358.21 5.97 | 12.45k 9.43 |357.50 5.96 13.56k 12.94 |497.51 7.96 | 13.10k 11.92 |549.16 8.94
This reads: the most bandwith-consuming host in the subnet is, which receives currently 41.72 kilobytes per second and transmits 30.40 kBps. The averages since the application startup By default, the output is sorted by current byte input (rx) counters. This behaviour can be changed using the -A (order by average rates), -P (order by packet counters), -O (order by output (tx) counters) options, for instance:
# stakhosts -i eth5 -cr 1 -PO
Would take the momentary transmit packet counters into consideration. The -b option might be used to force stakhosts to present counters in bits per second instead of bytes per second. The amount of hosts shown can be changed by using the -a option, to show the top 20 hosts:
# stakhosts -i eth5 -cr 1 -b -a 20
Options like -y or -x might be used to improve the readability, while the -d (dump) option makes the utility dump the counters in a form suitable for further processing using tools like awk or sed. By default, transfers between hosts in the specified networks (ie. in are not taken into the consideration while updating the counters. To make them being accounted too, use the -C option. Like in case of every stak component, the processed packets are subject to packet filtering. For instance, by issuing a command like:
# stakhosts -i eth5 -cr 1 -f 'tcp[13] & 2 != 0' -a 20
one could see the hosts generating the highest amount of TCP SYN packets (a likely sources of DDoS attacks).



-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.



-a N
Print N top nodes.
Use bit units. The output is to be presented in bits (b) rather than bytes (B).
Alternative ("dump") output format. Instead of showing top N nodes, stakhosts will dump the whole host list in a form that can be easily parsed by automated tools. The output format is:
<host IP>:<overall input bytes #>:<overall output bytes #>:<momentary input bytes #>:<momentary output bytes #>:<overall packet input #>:<overall packet output #>:<momentary packet input #>:<momentary packet output #>
Print spaces instead of "pipes" (|) as column separators. Normally, stakhosts will use characters imitating a vertical line ('|') to separate columns in order to improve readability. This option disables this feature.
Account local transfers too. stakhosts will also account 'local' transfers, ie. transfers between two hosts in IP classes specified. By default, such transfers are ignored.
Print total amount of transferred data instead of overall speed.
Consider overall transfer rates while sorting the host list.
Consider momentary transfer rates while sorting the host list (default).
Consider packet counters while sorting the host list.
Consider byte counters while sorting the list (default).
Consider output (TX) counters while sorting the list.
Consider input (RX) counters while sorting the list (default).



stakrate(1), stak(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: 14:59:02 GMT, March 21, 2004