User:Jau53/Pktstat
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pktstat
The pktstat program displays a real-time summary of packet activity on an interface. Each line displays the data rate associated with a particular class of packets. The class is determined by the packet header.
SYNOPSIS
pktstat [-1BcFlnpPtT] [-a abbrev] [-A file] [-i interface] [-k keeptime]
[-m maxbps] [-w waittime] [filter-expr]
DESCRIPTION
The pktstat program displays a real-time summary of packet activity on an
interface. Each line displays the data rate associated with different
classes of packets.
pktstat understands the following command line options:
-1 Single-shot (batch) mode. pktstat collects data for waittime
seconds (see -w option) then emits a line indicating the
number of flows detected, and the period of data capture in
seconds. Then, each flow line is printed in the form of the
number of data link octets associated with the flow, the
number of data link frames (packets), and then the flow
description.
-a abbrev
Add abbrev to the list of abbreviation patterns. (See below
for details.)
-A file
Read abbreviation patterns from the given file. (See
Abbreviations, below.) If the option -A none is given, then
default abbreviation files are not loaded.
-B Display data rates in bytes per second (Bps) instead of in
bits per second (bps).
-c Do not combine some packet classes into one class. For
example, TCP connections are kept as two separate flows.
-F Show full hostnames. Normally, hostnames are truncated to
the first component of their domain name before display.
-i interface
Listen on the given interface. If not specified, a suitable
interface is chosen.
-k keeptime
When no packets have been seen for a particular class, retain
an entry on the display for this many screen seconds.
Defaults to 10.
-l Display and sort flows by when they were last seen.
(Incompatible with -t)
-m maxbps
Fix the maximum bit rate for the interface at maxbps instead
of auto-detecting it.
-n Do not try and resolve hostnames or service port numbers.
-p Show packet counts instead of bit counts.
-P Do not try to put the interface into promiscuous mode.
-t "Top" mode. Sorts the display by bit count (or packet count
if -p was given) instead of by the name.
-T Show totals.
-w waittime
Refresh the display every waittime seconds. The default is 5
seconds.
filter-expr
Only consider packets matching the given filter-expr. If no
filter is provided, all packets are considered. See
tcpdump(8) for information on valid expressions.
If the terminal supports it, the display briefly highlights in bold new
connections or old connections carrying data after a period of
inactivity.
Simple statistics about the interface are also displayed such as the
current and average bit rates (measured just above the data link layer).
Load averages refer to bit rate decayed averages for the last 1, 5 and 15
minutes.
During display, the following keystrokes are recognised:
q quit
Ctrl-L redraw screen
t toggle the -t flag (top mode)
T toggle the -T flag (totals mode)
w allows changing of the -w flag value (wait time)
n toggle the -n flag (numeric display)
p toggle the -p flag (packets instead of bits)
b | B toggle the -B flag (bps or Bps)
f | F toggle the -F flag (full hostnames)
r reset collected statistics (min, max, etc.), flush flow
history and reset DNS/service and fragment caches
l show and sort flows by when they were last active
? toggle display of help/status text at the bottom of the
display
Packet classes
All packet classes, or flows, are "tagged" with a descriptive string,
such as ‘tcp ftpserver:20524 <-> cathexis:17771’.
In addition to being tagged, some protocol-state information can be
associated with a flow. This is displayed immediately below a flow line.
Descriptive information for FTP, HTTP, X11 and SUP connections is
determined from simple decoding of some packets. If the connection is
’open’, it is introduced with a right angle shape (+), otherwise it is
introduced with a hyphen character.
tcp www:80 <-> hamartia:19179
+ GET /index.html
Abbreviations
Abbreviation patterns are a way of further combining flows. As packets
are decoded, their flow name is constructed at the various protocol
layers. At address combining stage (where arrows such as ‘->’ are
inserted) and at the final display stage, flow names are checked against
a list of abbreviation patterns, and the abbreviation’s name substituted
if a match is found. For example, the pattern ‘* <-> *:domain’ will
match DNS packets in both the UDP and TCP layers.
Abbreviations take the form [abbrev@]pattern. The pattern part can
contain the wildcard character, asterisk ‘*’ which matches zero or more
non-space characters. The space character matches one or more whitespace
characters. Leading and trailing spaces are ignored.
If the optional abbrev is not specified, the the pattern text itself is
used as the abbreviation.
Patterns are checked in the order given on the command line or in the
files, i.e. as soon as one of the patterns matches a tag, no further
patterns are considered. Recall that patterns can be applied multiple
times to a tag.
A patterns file can contain blank lines, which are ignored. Comment
lines that commence with a ‘#’ character are also ignored.
After processing all command line abbreviations and abbreviation files,
pktstat looks for and loads the files .pktstatrc, $HOME/.pktstatrc and
/usr/etc/pktstatrc. This behaviour is suppressed by supplying an -A none
option.
EXAMPLES
Here are the contents of my .pktstatrc file:
dns @ udp *:domain <-> *
dns @ udp * <-> *:domain
irc @ udp 192.168.0.81:6666 <-> *
SEE ALSO
bpf(4), tcpdump(8)
AUTHORS
David Leonard, leonard@users.sourceforge.net
BUGS
DNS lookups can take too much time, possibly leading to missed packets.
The data rates do not take into account data link framing overhead or
compression savings at the data link layer.
The direction of traffic is not taken into account: both ingress and
egress data rates are combined. If you want to separate them, you will
need to use a filter expression.
Descriptive information for X11, FTP, HTTP and SUP flows is derived from
the very first packets sent on those protocols. If you start pktstat
after any of these flows have commenced, there may be no description
available for them.
Author
David Leonard, leonard@users.sourceforge.net
References[edit]
External links[edit]