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Explain, in full painful detail, what you need to do in order to do *useful* packet capture on Digital/Tru64 UNIX (and add "Tru64 UNIX" to the list of OS names).
2002-05-17 17:57:50 +08:00
.\" @(#) $Header: /tcpdump/master/tcpdump/Attic/tcpdump.1,v 1.120 2002-05-17 09:57:50 guy Exp $ (LBL)
Initial revision
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.\"
.\" Copyright (c) 1987, 1988, 1989, 1990, 1991, 1992, 1994, 1995, 1996, 1997
.\" The Regents of the University of California. All rights reserved.
.\" All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that: (1) source code distributions
.\" retain the above copyright notice and this paragraph in its entirety, (2)
.\" distributions including binary code include the above copyright notice and
.\" this paragraph in its entirety in the documentation or other materials
.\" provided with the distribution, and (3) all advertising materials mentioning
.\" features or use of this software display the following acknowledgement:
.\" ``This product includes software developed by the University of California,
.\" Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
.\" the University nor the names of its contributors may be used to endorse
.\" or promote products derived from this software without specific prior
.\" written permission.
.\" THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
.\" WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
.\" MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
.\"
adjusted date field
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.TH TCPDUMP 1 "3 January 2001"
Initial revision
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.SH NAME
tcpdump \- dump traffic on a network
.SH SYNOPSIS
.na
.B tcpdump
[
"-A" flag to print packet data in ASCII, from Jørgen Thomsen <jth@jth.net>.
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.B \-aAdeflnNOpqRStuvxX
Initial revision
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] [
.B \-c
.I count
Document the "-C" flag.
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]
.br
.ti +8
[
.B \-C
Don't call the argument to the "-C" flag "max_file_size", as it's not a maximum - the file size can get bigger than that by one packet's worth of data.
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.I file_size
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] [
.B \-F
.I file
]
.br
.ti +8
[
.B \-i
.I interface
From: Juergen Schoenwaelder <schoenw@ibr.cs.tu-bs.de> Here is a new version of the libsmi patch for tcpdump. It provides some bug fixes and some enhancements such as access checking and better range checking. The patch also fixed a few bugs in the print_snmp.c module of tcpdump itself (unrelated to the usage of libsmi).
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]
[
.B \-m
.I module
]
[
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.B \-r
.I file
]
From: Juergen Schoenwaelder <schoenw@ibr.cs.tu-bs.de> Here is a new version of the libsmi patch for tcpdump. It provides some bug fixes and some enhancements such as access checking and better range checking. The patch also fixed a few bugs in the print_snmp.c module of tcpdump itself (unrelated to the usage of libsmi).
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.br
.ti +8
Initial revision
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[
.B \-s
.I snaplen
]
[
.B \-T
.I type
]
[
.B \-w
.I file
]
From: Juergen Schoenwaelder <schoenw@ibr.cs.tu-bs.de> Here is a new version of the libsmi patch for tcpdump. It provides some bug fixes and some enhancements such as access checking and better range checking. The patch also fixed a few bugs in the print_snmp.c module of tcpdump itself (unrelated to the usage of libsmi).
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.br
.ti +8
Initial revision
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[
document -E. this option has very nasty effects and I'm still wondering if it is correct to include it in tcpdump.org distribution.
2000-01-15 15:54:15 +08:00
.B \-E
.I algo:secret
]
[
Initial revision
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.I expression
]
.br
.ad
.SH DESCRIPTION
.LP
\fITcpdump\fP prints out the headers of packets on a network interface
Expand the introductory discussion to: note at the beginning that tcpdump can write to a save file rather than printing a dissection of the packet, and can read from a saved file rather than from a network interrface; indicate what causes tcpdump to stop capturing (i.e., that, unless you've run it with "-c", you have to ^C or "kill" it); discuss the meanings of the packet counts it prints; indicate that ^T can be used on some OSes to get those packet counts while a capture is in progress; note that the special privileges required on various OSes are required only when capturing packets, not when reading a saved capture file; note that on at least some versions of Solaris you apparently have to be root in order to do a promiscuous capture. Consistently use italics to mark tcpdump's name.
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that match the boolean \fIexpression\fP. It can also be run with the
.B \-w
flag, which causes it to save the packet data to a file for later
analysis, and/or with the
.B \-b
flag, which causes it to read from a saved packet file rather than to
read packets from a network interface. In all cases, only packets that
match
.I expression
will be processed by
.IR tcpdump .
Initial revision
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.LP
Expand the introductory discussion to: note at the beginning that tcpdump can write to a save file rather than printing a dissection of the packet, and can read from a saved file rather than from a network interrface; indicate what causes tcpdump to stop capturing (i.e., that, unless you've run it with "-c", you have to ^C or "kill" it); discuss the meanings of the packet counts it prints; indicate that ^T can be used on some OSes to get those packet counts while a capture is in progress; note that the special privileges required on various OSes are required only when capturing packets, not when reading a saved capture file; note that on at least some versions of Solaris you apparently have to be root in order to do a promiscuous capture. Consistently use italics to mark tcpdump's name.
2001-07-06 06:58:29 +08:00
.I Tcpdump
will, if not run with the
.B \-c
flag, continue capturing packets until it is interrupted by a SIGINT
signal (generated, for example, by typing your interrupt character,
typically control-C) or a SIGTERM signal (typically generated with the
.BR kill (1)
command); if run with the
.B \-c
flag, it will capture packets until it is interrupted by a SIGINT or
SIGTERM signal or the specified number of packets have been processed.
.LP
When
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.I tcpdump
Expand the introductory discussion to: note at the beginning that tcpdump can write to a save file rather than printing a dissection of the packet, and can read from a saved file rather than from a network interrface; indicate what causes tcpdump to stop capturing (i.e., that, unless you've run it with "-c", you have to ^C or "kill" it); discuss the meanings of the packet counts it prints; indicate that ^T can be used on some OSes to get those packet counts while a capture is in progress; note that the special privileges required on various OSes are required only when capturing packets, not when reading a saved capture file; note that on at least some versions of Solaris you apparently have to be root in order to do a promiscuous capture. Consistently use italics to mark tcpdump's name.
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finishes capturing packets, it will report counts of:
.IP
packets ``received by filter'' (the meaning of this depends on the OS on
which you're running
.IR tcpdump ,
and possibly on the way the OS was configured - if a filter was
specified on the command line, on some OSes it counts packets regardless
of whether they were matched by the filter expression, and on other OSes
it counts only packets that were matched by the filter expression and
were processed by
.IR tcpdump );
.IP
packets ``dropped by kernel'' (this is the number of packets that were
dropped, due to a lack of buffer space, by the packet capture mechanism
in the OS on which
.I tcpdump
is running, if the OS reports that information to applications; if not,
it will be reported as 0).
.LP
On platforms that support the SIGINFO signal, such as most BSDs, it will
report those counts when it receives a SIGINFO signal (generated, for
example, by typing your ``status'' character, typically control-T) and
will continue capturing packets.
.LP
Reading packets from a network interface may require that you have
special privileges:
.TP
.B Under SunOS 3.x or 4.x with NIT or BPF:
You must have read access to
Initial revision
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.I /dev/nit
or
.IR /dev/bpf* .
Expand the introductory discussion to: note at the beginning that tcpdump can write to a save file rather than printing a dissection of the packet, and can read from a saved file rather than from a network interrface; indicate what causes tcpdump to stop capturing (i.e., that, unless you've run it with "-c", you have to ^C or "kill" it); discuss the meanings of the packet counts it prints; indicate that ^T can be used on some OSes to get those packet counts while a capture is in progress; note that the special privileges required on various OSes are required only when capturing packets, not when reading a saved capture file; note that on at least some versions of Solaris you apparently have to be root in order to do a promiscuous capture. Consistently use italics to mark tcpdump's name.
2001-07-06 06:58:29 +08:00
.TP
.B Under Solaris with DLPI:
"pcap-dlpi.c" opens the DLPI devices read/write, not read-only, so, on Solaris, you need read/write access to the network pseudo-devices.
2001-01-18 02:53:20 +08:00
You must have read/write access to the network pseudo device, e.g.
Initial revision
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.IR /dev/le .
Expand the introductory discussion to: note at the beginning that tcpdump can write to a save file rather than printing a dissection of the packet, and can read from a saved file rather than from a network interrface; indicate what causes tcpdump to stop capturing (i.e., that, unless you've run it with "-c", you have to ^C or "kill" it); discuss the meanings of the packet counts it prints; indicate that ^T can be used on some OSes to get those packet counts while a capture is in progress; note that the special privileges required on various OSes are required only when capturing packets, not when reading a saved capture file; note that on at least some versions of Solaris you apparently have to be root in order to do a promiscuous capture. Consistently use italics to mark tcpdump's name.
2001-07-06 06:58:29 +08:00
On at least some versions of Solaris, however, this is not sufficient to
allow
.I tcpdump
to capture in promiscuous mode; on those versions of Solaris, you must
be root, or
.I tcpdump
must be installed setuid to root, in order to capture in promiscuous
Note that, although you can, in theory, do captures on Solaris if you're not root, those captures can't be done in promiscuous mode, at least on later versions of Solaris, and thus may not include any outgoing packets and, therefore, those captures may not be very useful.
2002-02-08 14:45:05 +08:00
mode. Note that, on many (perhaps all) interfaces, if you don't capture
in promiscuous mode, you will not see any outgoing packets, so a capture
not done in promiscuous mode may not be very useful.
Expand the introductory discussion to: note at the beginning that tcpdump can write to a save file rather than printing a dissection of the packet, and can read from a saved file rather than from a network interrface; indicate what causes tcpdump to stop capturing (i.e., that, unless you've run it with "-c", you have to ^C or "kill" it); discuss the meanings of the packet counts it prints; indicate that ^T can be used on some OSes to get those packet counts while a capture is in progress; note that the special privileges required on various OSes are required only when capturing packets, not when reading a saved capture file; note that on at least some versions of Solaris you apparently have to be root in order to do a promiscuous capture. Consistently use italics to mark tcpdump's name.
2001-07-06 06:58:29 +08:00
.TP
.B Under HP-UX with DLPI:
You must be root or
.I tcpdump
must be installed setuid to root.
.TP
Initial revision
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.B Under IRIX with snoop:
Expand the introductory discussion to: note at the beginning that tcpdump can write to a save file rather than printing a dissection of the packet, and can read from a saved file rather than from a network interrface; indicate what causes tcpdump to stop capturing (i.e., that, unless you've run it with "-c", you have to ^C or "kill" it); discuss the meanings of the packet counts it prints; indicate that ^T can be used on some OSes to get those packet counts while a capture is in progress; note that the special privileges required on various OSes are required only when capturing packets, not when reading a saved capture file; note that on at least some versions of Solaris you apparently have to be root in order to do a promiscuous capture. Consistently use italics to mark tcpdump's name.
2001-07-06 06:58:29 +08:00
You must be root or
.I tcpdump
must be installed setuid to root.
.TP
Initial revision
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.B Under Linux:
Expand the introductory discussion to: note at the beginning that tcpdump can write to a save file rather than printing a dissection of the packet, and can read from a saved file rather than from a network interrface; indicate what causes tcpdump to stop capturing (i.e., that, unless you've run it with "-c", you have to ^C or "kill" it); discuss the meanings of the packet counts it prints; indicate that ^T can be used on some OSes to get those packet counts while a capture is in progress; note that the special privileges required on various OSes are required only when capturing packets, not when reading a saved capture file; note that on at least some versions of Solaris you apparently have to be root in order to do a promiscuous capture. Consistently use italics to mark tcpdump's name.
2001-07-06 06:58:29 +08:00
You must be root or
.I tcpdump
must be installed setuid to root.
.TP
Explain, in full painful detail, what you need to do in order to do *useful* packet capture on Digital/Tru64 UNIX (and add "Tru64 UNIX" to the list of OS names).
2002-05-17 17:57:50 +08:00
.B Under Ultrix and Digital UNIX/Tru64 UNIX:
Any user may capture network traffic with
Expand the introductory discussion to: note at the beginning that tcpdump can write to a save file rather than printing a dissection of the packet, and can read from a saved file rather than from a network interrface; indicate what causes tcpdump to stop capturing (i.e., that, unless you've run it with "-c", you have to ^C or "kill" it); discuss the meanings of the packet counts it prints; indicate that ^T can be used on some OSes to get those packet counts while a capture is in progress; note that the special privileges required on various OSes are required only when capturing packets, not when reading a saved capture file; note that on at least some versions of Solaris you apparently have to be root in order to do a promiscuous capture. Consistently use italics to mark tcpdump's name.
2001-07-06 06:58:29 +08:00
.IR tcpdump .
Explain, in full painful detail, what you need to do in order to do *useful* packet capture on Digital/Tru64 UNIX (and add "Tru64 UNIX" to the list of OS names).
2002-05-17 17:57:50 +08:00
However, no user (not even the super-user) can capture in promiscuous
mode on an interface unless the super-user has enabled promiscuous-mode
operation on that interface using
.IR pfconfig (8),
and no user (not even the super-user) can capture unicast traffic
received by or sent by the machine on an interface unless the super-user
has enabled copy-all-mode operation on that interface using
.IR pfconfig ,
so
.I useful
packet capture on an interface probably requires that either
promiscuous-mode or copy-all-mode operation, or both modes of
operation, be enabled on that interface.
Expand the introductory discussion to: note at the beginning that tcpdump can write to a save file rather than printing a dissection of the packet, and can read from a saved file rather than from a network interrface; indicate what causes tcpdump to stop capturing (i.e., that, unless you've run it with "-c", you have to ^C or "kill" it); discuss the meanings of the packet counts it prints; indicate that ^T can be used on some OSes to get those packet counts while a capture is in progress; note that the special privileges required on various OSes are required only when capturing packets, not when reading a saved capture file; note that on at least some versions of Solaris you apparently have to be root in order to do a promiscuous capture. Consistently use italics to mark tcpdump's name.
2001-07-06 06:58:29 +08:00
.TP
Initial revision
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.B Under BSD:
You must have read access to
.IR /dev/bpf* .
Expand the introductory discussion to: note at the beginning that tcpdump can write to a save file rather than printing a dissection of the packet, and can read from a saved file rather than from a network interrface; indicate what causes tcpdump to stop capturing (i.e., that, unless you've run it with "-c", you have to ^C or "kill" it); discuss the meanings of the packet counts it prints; indicate that ^T can be used on some OSes to get those packet counts while a capture is in progress; note that the special privileges required on various OSes are required only when capturing packets, not when reading a saved capture file; note that on at least some versions of Solaris you apparently have to be root in order to do a promiscuous capture. Consistently use italics to mark tcpdump's name.
2001-07-06 06:58:29 +08:00
.LP
Reading a saved packet file doesn't require special privileges.
Initial revision
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.SH OPTIONS
.TP
"-A" flag to print packet data in ASCII, from Jørgen Thomsen <jth@jth.net>.
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.TP
.B \-A
Print each packet (minus its link level header) in ASCII. Handy for
capturing web pages.
Initial revision
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.B \-a
Attempt to convert network and broadcast addresses to names.
.TP
.B \-c
Exit after receiving \fIcount\fP packets.
.TP
Document the "-C" flag.
2001-10-03 15:41:31 +08:00
.B \-C
Before writing a raw packet to a savefile, check whether the file is
Don't call the argument to the "-C" flag "max_file_size", as it's not a maximum - the file size can get bigger than that by one packet's worth of data.
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currently larger than \fIfile_size\fP and, if so, close the current
savefile and open a new one. Savefiles after the first savefile will
have the name specified with the
Document the "-C" flag.
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.B \-w
flag, with a number after it, starting at 2 and continuing upward.
Don't call the argument to the "-C" flag "max_file_size", as it's not a maximum - the file size can get bigger than that by one packet's worth of data.
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The units of \fIfile_size\fP are millions of bytes (1,000,000 bytes,
Document the "-C" flag.
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not 1,048,576 bytes).
.TP
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.B \-d
Dump the compiled packet-matching code in a human readable form to
standard output and stop.
.TP
.B \-dd
Dump packet-matching code as a
.B C
program fragment.
.TP
.B \-ddd
Dump packet-matching code as decimal numbers (preceded with a count).
.TP
.B \-e
Print the link-level header on each dump line.
.TP
document -E. this option has very nasty effects and I'm still wondering if it is correct to include it in tcpdump.org distribution.
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.B \-E
break line after sentence, nroff cleanup
2001-06-25 11:18:27 +08:00
Use \fIalgo:secret\fP for decrypting IPsec ESP packets.
whitespace at EOL
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Algorithms may be
\fBdes-cbc\fP,
\fB3des-cbc\fP,
\fBblowfish-cbc\fP,
\fBrc3-cbc\fP,
\fBcast128-cbc\fP, or
Add documentation for Token Ring. Change some font choices to match the conventions used historically in this man page (use boldface for literal strings, italics for variables, and italics for "tcpdump" when it refers to the name of the program).
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\fBnone\fP.
The default is \fBdes-cbc\fP.
The ability to decrypt packets is only present if \fItcpdump\fP was compiled
document -E. this option has very nasty effects and I'm still wondering if it is correct to include it in tcpdump.org distribution.
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with cryptography enabled.
\fIsecret\fP the ascii text for ESP secret key.
We cannot take arbitrary binary value at this moment.
The option assumes RFC2406 ESP, not RFC1827 ESP.
The option is only for debugging purposes, and
Add documentation for Token Ring. Change some font choices to match the conventions used historically in this man page (use boldface for literal strings, italics for variables, and italics for "tcpdump" when it refers to the name of the program).
2000-07-25 14:09:32 +08:00
the use of this option with truly `secret' key is discouraged.
document -E. this option has very nasty effects and I'm still wondering if it is correct to include it in tcpdump.org distribution.
2000-01-15 15:54:15 +08:00
By presenting IPsec secret key onto command line
Add documentation for Token Ring. Change some font choices to match the conventions used historically in this man page (use boldface for literal strings, italics for variables, and italics for "tcpdump" when it refers to the name of the program).
2000-07-25 14:09:32 +08:00
you make it visible to others, via
.IR ps (1)
and other occasions.
document -E. this option has very nasty effects and I'm still wondering if it is correct to include it in tcpdump.org distribution.
2000-01-15 15:54:15 +08:00
.TP
Initial revision
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.B \-f
Print `foreign' internet addresses numerically rather than symbolically
(this option is intended to get around serious brain damage in
Sun's yp server \(em usually it hangs forever translating non-local
internet numbers).
.TP
.B \-F
Use \fIfile\fP as input for the filter expression.
An additional expression given on the command line is ignored.
.TP
.B \-i
Listen on \fIinterface\fP.
If unspecified, \fItcpdump\fP searches the system interface list for the
lowest numbered, configured up interface (excluding loopback).
Ties are broken by choosing the earliest match.
Document the "any" interface, and note that captures on it won't be done in promiscuous mode.
2001-01-18 12:37:23 +08:00
.IP
On Linux systems with 2.2 or later kernels, an
.I interface
break line after sentence, nroff cleanup
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argument of ``any'' can be used to capture packets from all interfaces.
Document the "any" interface, and note that captures on it won't be done in promiscuous mode.
2001-01-18 12:37:23 +08:00
Note that captures on the ``any'' device will not be done in promiscuous
mode.
Initial revision
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.TP
.B \-l
break line after sentence, nroff cleanup
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Make stdout line buffered.
Useful if you want to see the data
while capturing it.
E.g.,
Initial revision
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.br
``tcpdump\ \ \-l\ \ |\ \ tee dat'' or
``tcpdump\ \ \-l \ \ > dat\ \ &\ \ tail\ \ \-f\ \ dat''.
.TP
Document the "-u" flag (from the Red Hat 7.2 tcpdump man page). Put the options in dictionary order.
2001-10-27 16:18:44 +08:00
.B \-m
Load SMI MIB module definitions from file \fImodule\fR.
This option
can be used several times to load several MIB modules into \fItcpdump\fP.
.TP
Initial revision
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.B \-n
Don't convert addresses (i.e., host addresses, port numbers, etc.) to names.
.TP
.B \-N
break line after sentence, nroff cleanup
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Don't print domain name qualification of host names.
E.g.,
Initial revision
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if you give this flag then \fItcpdump\fP will print ``nic''
instead of ``nic.ddn.mil''.
.TP
.B \-O
break line after sentence, nroff cleanup
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Do not run the packet-matching code optimizer.
This is useful only
Initial revision
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if you suspect a bug in the optimizer.
.TP
.B \-p
\fIDon't\fP put the interface
break line after sentence, nroff cleanup
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into promiscuous mode.
Note that the interface might be in promiscuous
Initial revision
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mode for some other reason; hence, `-p' cannot be used as an abbreviation for
`ether host {local-hw-addr} or ether broadcast'.
.TP
.B \-q
break line after sentence, nroff cleanup
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Quick (quiet?) output.
Print less protocol information so output
Initial revision
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lines are shorter.
.TP
Document the "-u" flag (from the Red Hat 7.2 tcpdump man page). Put the options in dictionary order.
2001-10-27 16:18:44 +08:00
.B \-R
Assume ESP/AH packets to be based on old specification (RFC1825 to RFC1829).
If specified, \fItcpdump\fP will not print replay prevention field.
Since there is no protocol version field in ESP/AH specification,
\fItcpdump\fP cannot deduce the version of ESP/AH protocol.
.TP
Initial revision
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.B \-r
Read packets from \fIfile\fR (which was created with the -w option).
Standard input is used if \fIfile\fR is ``-''.
.TP
Document the "-u" flag (from the Red Hat 7.2 tcpdump man page). Put the options in dictionary order.
2001-10-27 16:18:44 +08:00
.B \-S
Print absolute, rather than relative, TCP sequence numbers.
.TP
Initial revision
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.B \-s
Snarf \fIsnaplen\fP bytes of data from each packet rather than the
default of 68 (with SunOS's NIT, the minimum is actually 96).
68 bytes is adequate for IP, ICMP, TCP
and UDP but may truncate protocol information from name server and NFS
break line after sentence, nroff cleanup
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packets (see below).
Packets truncated because of a limited snapshot
Initial revision
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are indicated in the output with ``[|\fIproto\fP]'', where \fIproto\fP
is the name of the protocol level at which the truncation has occurred.
Note that taking larger snapshots both increases
the amount of time it takes to process packets and, effectively,
break line after sentence, nroff cleanup
2001-06-25 11:18:27 +08:00
decreases the amount of packet buffering.
This may cause packets to be
lost.
You should limit \fIsnaplen\fP to the smallest number that will
capture the protocol information you're interested in.
Setting
document `-s 0'
2000-04-21 18:32:59 +08:00
\fIsnaplen\fP to 0 means use the required length to catch whole packets.
Initial revision
1999-10-08 07:47:09 +08:00
.TP
.B \-T
Force packets selected by "\fIexpression\fP" to be interpreted the
break line after sentence, nroff cleanup
2001-06-25 11:18:27 +08:00
specified \fItype\fR.
Currently known types are
add -T cnfp
2000-04-27 18:07:05 +08:00
\fBcnfp\fR (Cisco NetFlow protocol),
Initial revision
1999-10-08 07:47:09 +08:00
\fBrpc\fR (Remote Procedure Call),
\fBrtp\fR (Real-Time Applications protocol),
\fBrtcp\fR (Real-Time Applications control protocol),
From: Juergen Schoenwaelder <schoenw@ibr.cs.tu-bs.de> Here is a new version of the libsmi patch for tcpdump. It provides some bug fixes and some enhancements such as access checking and better range checking. The patch also fixed a few bugs in the print_snmp.c module of tcpdump itself (unrelated to the usage of libsmi).
1999-12-14 02:06:13 +08:00
\fBsnmp\fR (Simple Network Management Protocol),
Initial revision
1999-10-08 07:47:09 +08:00
\fBvat\fR (Visual Audio Tool),
and
Bring in KAME IPv6 tcpdump. replaces esp/ah/isakmp decoder. Hope I did not break anything. Portability on IPv4-only node needs checking, I'll do this very soon. (sorry for rather jumbo commit) XXx what is _FAVOR_BSD?
1999-10-30 13:11:06 +08:00
\fBwb\fR (distributed White Board).
.TP
Initial revision
1999-10-08 07:47:09 +08:00
.B \-t
\fIDon't\fP print a timestamp on each dump line.
.TP
.B \-tt
Print an unformatted timestamp on each dump line.
.TP
Patch from Motonori Shindo to update the man page to reflect additional time stamp print formats added a while ago.
2001-03-04 08:17:28 +08:00
.B \-ttt
whitespace at EOL
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Print a delta (in micro-seconds) between current and previous line
Patch from Motonori Shindo to update the man page to reflect additional time stamp print formats added a while ago.
2001-03-04 08:17:28 +08:00
on each dump line.
.TP
.B \-tttt
Print a timestamp in default format proceeded by date on each dump line.
Fix a formatto.
2002-05-07 12:00:09 +08:00
.TP
Document the "-u" flag (from the Red Hat 7.2 tcpdump man page). Put the options in dictionary order.
2001-10-27 16:18:44 +08:00
.B \-u
Print undecoded NFS handles.
Patch from Motonori Shindo to update the man page to reflect additional time stamp print formats added a while ago.
2001-03-04 08:17:28 +08:00
.TP
Initial revision
1999-10-08 07:47:09 +08:00
.B \-v
break line after sentence, nroff cleanup
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(Slightly more) verbose output.
For example, the time to live,
print IP length. From Kevin Steves <stevesk@sweden.hp.com>
2000-07-29 14:06:27 +08:00
identification, total length and options in an IP packet are printed.
Also enables additional packet integrity checks such as verifying the
IP and ICMP header checksum.
Initial revision
1999-10-08 07:47:09 +08:00
.TP
.B \-vv
break line after sentence, nroff cleanup
2001-06-25 11:18:27 +08:00
Even more verbose output.
For example, additional fields are
Patches from Pekka Savola <pekkas@netcore.fi> to quiet down SMB a little. I changed his patches to actually use -vv. Obviously tcpdump actually needs more-targeted -v flags (like "-v smb").
2001-02-21 03:28:02 +08:00
printed from NFS reply packets, and SMB packets are fully decoded.
Initial revision
1999-10-08 07:47:09 +08:00
.TP
add print-ascii.c and print-telnet.c from netbsd. - add -X option for ascii printing. - telnet command sequences (ff xx xx) will be dumped with -vvv -X.
1999-12-22 23:44:09 +08:00
.B \-vvv
break line after sentence, nroff cleanup
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Even more verbose output.
For example,
add print-ascii.c and print-telnet.c from netbsd. - add -X option for ascii printing. - telnet command sequences (ff xx xx) will be dumped with -vvv -X.
1999-12-22 23:44:09 +08:00
telnet \fBSB\fP ... \fBSE\fP options
break line after sentence, nroff cleanup
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are printed in full.
With
add print-ascii.c and print-telnet.c from netbsd. - add -X option for ascii printing. - telnet command sequences (ff xx xx) will be dumped with -vvv -X.
1999-12-22 23:44:09 +08:00
.B \-X
telnet options are printed in hex as well.
.TP
Initial revision
1999-10-08 07:47:09 +08:00
.B \-w
Write the raw packets to \fIfile\fR rather than parsing and printing
break line after sentence, nroff cleanup
2001-06-25 11:18:27 +08:00
them out.
They can later be printed with the \-r option.
Initial revision
1999-10-08 07:47:09 +08:00
Standard output is used if \fIfile\fR is ``-''.
.TP
.B \-x
Print each packet (minus its link level header) in hex.
The smaller of the entire packet or
.I snaplen
bytes will be printed.
add print-ascii.c and print-telnet.c from netbsd. - add -X option for ascii printing. - telnet command sequences (ff xx xx) will be dumped with -vvv -X.
1999-12-22 23:44:09 +08:00
.TP
.B \-X
break line after sentence, nroff cleanup
2001-06-25 11:18:27 +08:00
When printing hex, print ascii too.
Thus if
add print-ascii.c and print-telnet.c from netbsd. - add -X option for ascii printing. - telnet command sequences (ff xx xx) will be dumped with -vvv -X.
1999-12-22 23:44:09 +08:00
.B \-x
is also set, the packet is printed in hex/ascii.
This is very handy for analysing new protocols.
Even if
.B \-x
is not also set, some parts of some packets may be printed
in hex/ascii.
Initial revision
1999-10-08 07:47:09 +08:00
.IP "\fI expression\fP"
.RS
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selects which packets will be dumped.
If no \fIexpression\fP
is given, all packets on the net will be dumped.
Otherwise,
Initial revision
1999-10-08 07:47:09 +08:00
only packets for which \fIexpression\fP is `true' will be dumped.
.LP
The \fIexpression\fP consists of one or more
.I primitives.
Primitives usually consist of an
.I id
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2001-06-25 11:18:27 +08:00
(name or number) preceded by one or more qualifiers.
There are three
Initial revision
1999-10-08 07:47:09 +08:00
different kinds of qualifier:
.IP \fItype\fP
qualifiers say what kind of thing the id name or number refers to.
Possible types are
.BR host ,
.B net
and
.BR port .
break line after sentence, nroff cleanup
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E.g., `host foo', `net 128.3', `port 20'.
If there is no type
Initial revision
1999-10-08 07:47:09 +08:00
qualifier,
.B host
is assumed.
.IP \fIdir\fP
qualifiers specify a particular transfer direction to and/or from
"iso" is *not* a qualifier that restricts address or port matches to a particular protocol. Document the new "clnp" ISO protocol type. Formatting nits.
2000-10-28 18:23:38 +08:00
.IR id .
Initial revision
1999-10-08 07:47:09 +08:00
Possible directions are
.BR src ,
.BR dst ,
.B "src or dst"
and
.B "src and"
.BR dst .
break line after sentence, nroff cleanup
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E.g., `src foo', `dst net 128.3', `src or dst port ftp-data'.
If
Initial revision
1999-10-08 07:47:09 +08:00
there is no dir qualifier,
.B "src or dst"
is assumed.
For `null' link layers (i.e. point to point protocols such as slip) the
.B inbound
and
.B outbound
qualifiers can be used to specify a desired direction.
.IP \fIproto\fP
break line after sentence, nroff cleanup
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qualifiers restrict the match to a particular protocol.
Possible
Initial revision
1999-10-08 07:47:09 +08:00
protos are:
.BR ether ,
.BR fddi ,
Add documentation for Token Ring. Change some font choices to match the conventions used historically in this man page (use boldface for literal strings, italics for variables, and italics for "tcpdump" when it refers to the name of the program).
2000-07-25 14:09:32 +08:00
.BR tr ,
Initial revision
1999-10-08 07:47:09 +08:00
.BR ip ,
Bring in KAME IPv6 tcpdump. replaces esp/ah/isakmp decoder. Hope I did not break anything. Portability on IPv4-only node needs checking, I'll do this very soon. (sorry for rather jumbo commit) XXx what is _FAVOR_BSD?
1999-10-30 13:11:06 +08:00
.BR ip6 ,
Initial revision
1999-10-08 07:47:09 +08:00
.BR arp ,
.BR rarp ,
.BR decnet ,
.B tcp
and
.BR udp .
break line after sentence, nroff cleanup
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E.g., `ether src foo', `arp net 128.3', `tcp port 21'.
If there is
Initial revision
1999-10-08 07:47:09 +08:00
no proto qualifier, all protocols consistent with the type are
break line after sentence, nroff cleanup
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assumed.
E.g., `src foo' means `(ip or arp or rarp) src foo'
Initial revision
1999-10-08 07:47:09 +08:00
(except the latter is not legal syntax), `net bar' means `(ip or
arp or rarp) net bar' and `port 53' means `(tcp or udp) port 53'.
.LP
[`fddi' is actually an alias for `ether'; the parser treats them
identically as meaning ``the data link level used on the specified
network interface.'' FDDI headers contain Ethernet-like source
and destination addresses, and often contain Ethernet-like packet
types, so you can filter on these FDDI fields just as with the
break line after sentence, nroff cleanup
2001-06-25 11:18:27 +08:00
analogous Ethernet fields.
FDDI headers also contain other fields,
Add documentation for Token Ring. Change some font choices to match the conventions used historically in this man page (use boldface for literal strings, italics for variables, and italics for "tcpdump" when it refers to the name of the program).
2000-07-25 14:09:32 +08:00
but you cannot name them explicitly in a filter expression.
.LP
Similarly, `tr' is an alias for `ether'; the previous paragraph's
statements about FDDI headers also apply to Token Ring headers.]
Initial revision
1999-10-08 07:47:09 +08:00
.LP
In addition to the above, there are some special `primitive' keywords
that don't follow the pattern:
.BR gateway ,
.BR broadcast ,
.BR less ,
.B greater
break line after sentence, nroff cleanup
2001-06-25 11:18:27 +08:00
and arithmetic expressions.
All of these are described below.
Initial revision
1999-10-08 07:47:09 +08:00
.LP
More complex filter expressions are built up by using the words
.BR and ,
.B or
and
.B not
break line after sentence, nroff cleanup
2001-06-25 11:18:27 +08:00
to combine primitives.
E.g., `host foo and not port ftp and not port ftp-data'.
To save typing, identical qualifier lists can be omitted.
E.g.,
Initial revision
1999-10-08 07:47:09 +08:00
`tcp dst port ftp or ftp-data or domain' is exactly the same as
`tcp dst port ftp or tcp dst port ftp-data or tcp dst port domain'.
.LP
Allowable primitives are:
.IP "\fBdst host \fIhost\fR"
Bring in KAME IPv6 tcpdump. replaces esp/ah/isakmp decoder. Hope I did not break anything. Portability on IPv4-only node needs checking, I'll do this very soon. (sorry for rather jumbo commit) XXx what is _FAVOR_BSD?
1999-10-30 13:11:06 +08:00
True if the IPv4/v6 destination field of the packet is \fIhost\fP,
Initial revision
1999-10-08 07:47:09 +08:00
which may be either an address or a name.
.IP "\fBsrc host \fIhost\fR"
Bring in KAME IPv6 tcpdump. replaces esp/ah/isakmp decoder. Hope I did not break anything. Portability on IPv4-only node needs checking, I'll do this very soon. (sorry for rather jumbo commit) XXx what is _FAVOR_BSD?
1999-10-30 13:11:06 +08:00
True if the IPv4/v6 source field of the packet is \fIhost\fP.
Initial revision
1999-10-08 07:47:09 +08:00
.IP "\fBhost \fIhost\fP
Bring in KAME IPv6 tcpdump. replaces esp/ah/isakmp decoder. Hope I did not break anything. Portability on IPv4-only node needs checking, I'll do this very soon. (sorry for rather jumbo commit) XXx what is _FAVOR_BSD?
1999-10-30 13:11:06 +08:00
True if either the IPv4/v6 source or destination of the packet is \fIhost\fP.
Initial revision
1999-10-08 07:47:09 +08:00
Any of the above host expressions can be prepended with the keywords,
Bring in KAME IPv6 tcpdump. replaces esp/ah/isakmp decoder. Hope I did not break anything. Portability on IPv4-only node needs checking, I'll do this very soon. (sorry for rather jumbo commit) XXx what is _FAVOR_BSD?
1999-10-30 13:11:06 +08:00
\fBip\fP, \fBarp\fP, \fBrarp\fP, or \fBip6\fP as in:
Initial revision
1999-10-08 07:47:09 +08:00
.in +.5i
.nf
\fBip host \fIhost\fR
.fi
.in -.5i
which is equivalent to:
.in +.5i
.nf
\fBether proto \fI\\ip\fB and host \fIhost\fR
.fi
.in -.5i
If \fIhost\fR is a name with multiple IP addresses, each address will
be checked for a match.
.IP "\fBether dst \fIehost\fP
break line after sentence, nroff cleanup
2001-06-25 11:18:27 +08:00
True if the ethernet destination address is \fIehost\fP.
\fIEhost\fP
Initial revision
1999-10-08 07:47:09 +08:00
may be either a name from /etc/ethers or a number (see
.IR ethers (3N)
for numeric format).
.IP "\fBether src \fIehost\fP
True if the ethernet source address is \fIehost\fP.
.IP "\fBether host \fIehost\fP
True if either the ethernet source or destination address is \fIehost\fP.
.IP "\fBgateway\fP \fIhost\fP
break line after sentence, nroff cleanup
2001-06-25 11:18:27 +08:00
True if the packet used \fIhost\fP as a gateway.
I.e., the ethernet
Initial revision
1999-10-08 07:47:09 +08:00
source or destination address was \fIhost\fP but neither the IP source
break line after sentence, nroff cleanup
2001-06-25 11:18:27 +08:00
nor the IP destination was \fIhost\fP.
\fIHost\fP must be a name and
When discussing the "gateway" keyword, don't say that the host must be found in "/etc/hosts" and "/etc/ethers", say it must be found by the host-name-to-IP-address resolution mechanism and the host-name-to-Ethernet- address resolution mechanism - the host could be in DNS, for example.
2001-06-22 16:52:05 +08:00
must be found both by the machine's host-name-to-IP-address resolution
mechanisms (host name file, DNS, NIS, etc.) and by the machine's
break line after sentence, nroff cleanup
2001-06-25 11:18:27 +08:00
host-name-to-Ethernet-address resolution mechanism (/etc/ethers, etc.).
When discussing the "gateway" keyword, don't say that the host must be found in "/etc/hosts" and "/etc/ethers", say it must be found by the host-name-to-IP-address resolution mechanism and the host-name-to-Ethernet- address resolution mechanism - the host could be in DNS, for example.
2001-06-22 16:52:05 +08:00
(An equivalent expression is
Initial revision
1999-10-08 07:47:09 +08:00
.in +.5i
.nf
\fBether host \fIehost \fBand not host \fIhost\fR
.fi
.in -.5i
which can be used with either names or numbers for \fIhost / ehost\fP.)
Bring in KAME IPv6 tcpdump. replaces esp/ah/isakmp decoder. Hope I did not break anything. Portability on IPv4-only node needs checking, I'll do this very soon. (sorry for rather jumbo commit) XXx what is _FAVOR_BSD?
1999-10-30 13:11:06 +08:00
This syntax does not work in IPv6-enabled configuration at this moment.
Initial revision
1999-10-08 07:47:09 +08:00
.IP "\fBdst net \fInet\fR"
Bring in KAME IPv6 tcpdump. replaces esp/ah/isakmp decoder. Hope I did not break anything. Portability on IPv4-only node needs checking, I'll do this very soon. (sorry for rather jumbo commit) XXx what is _FAVOR_BSD?
1999-10-30 13:11:06 +08:00
True if the IPv4/v6 destination address of the packet has a network
break line after sentence, nroff cleanup
2001-06-25 11:18:27 +08:00
number of \fInet\fP.
\fINet\fP may be either a name from /etc/networks
Initial revision
1999-10-08 07:47:09 +08:00
or a network number (see \fInetworks(4)\fP for details).
.IP "\fBsrc net \fInet\fR"
Bring in KAME IPv6 tcpdump. replaces esp/ah/isakmp decoder. Hope I did not break anything. Portability on IPv4-only node needs checking, I'll do this very soon. (sorry for rather jumbo commit) XXx what is _FAVOR_BSD?
1999-10-30 13:11:06 +08:00
True if the IPv4/v6 source address of the packet has a network
Initial revision
1999-10-08 07:47:09 +08:00
number of \fInet\fP.
.IP "\fBnet \fInet\fR"
Bring in KAME IPv6 tcpdump. replaces esp/ah/isakmp decoder. Hope I did not break anything. Portability on IPv4-only node needs checking, I'll do this very soon. (sorry for rather jumbo commit) XXx what is _FAVOR_BSD?
1999-10-30 13:11:06 +08:00
True if either the IPv4/v6 source or destination address of the packet has a network
Initial revision
1999-10-08 07:47:09 +08:00
number of \fInet\fP.
Clean up the description of "net <net> mask <netmask>" slightly. Put in a missing "with" in the description of "net <net>/<mask>".
2001-09-04 05:59:28 +08:00
.IP "\fBnet \fInet\fR \fBmask \fInetmask\fR"
True if the IP address matches \fInet\fR with the specific \fInetmask\fR.
Initial revision
1999-10-08 07:47:09 +08:00
May be qualified with \fBsrc\fR or \fBdst\fR.
Bring in KAME IPv6 tcpdump. replaces esp/ah/isakmp decoder. Hope I did not break anything. Portability on IPv4-only node needs checking, I'll do this very soon. (sorry for rather jumbo commit) XXx what is _FAVOR_BSD?
1999-10-30 13:11:06 +08:00
Note that this syntax is not valid for IPv6 \fInet\fR.
Initial revision
1999-10-08 07:47:09 +08:00
.IP "\fBnet \fInet\fR/\fIlen\fR"
Clean up the description of "net <net> mask <netmask>" slightly. Put in a missing "with" in the description of "net <net>/<mask>".
2001-09-04 05:59:28 +08:00
True if the IPv4/v6 address matches \fInet\fR with a netmask \fIlen\fR
bits wide.
Initial revision
1999-10-08 07:47:09 +08:00
May be qualified with \fBsrc\fR or \fBdst\fR.
.IP "\fBdst port \fIport\fR"
Bring in KAME IPv6 tcpdump. replaces esp/ah/isakmp decoder. Hope I did not break anything. Portability on IPv4-only node needs checking, I'll do this very soon. (sorry for rather jumbo commit) XXx what is _FAVOR_BSD?
1999-10-30 13:11:06 +08:00
True if the packet is ip/tcp, ip/udp, ip6/tcp or ip6/udp and has a
Initial revision
1999-10-08 07:47:09 +08:00
destination port value of \fIport\fP.
The \fIport\fP can be a number or a name used in /etc/services (see
.IR tcp (4P)
and
.IR udp (4P)).
If a name is used, both the port
break line after sentence, nroff cleanup
2001-06-25 11:18:27 +08:00
number and protocol are checked.
If a number or ambiguous name is used,
Initial revision
1999-10-08 07:47:09 +08:00
only the port number is checked (e.g., \fBdst port 513\fR will print both
tcp/login traffic and udp/who traffic, and \fBport domain\fR will print
both tcp/domain and udp/domain traffic).
.IP "\fBsrc port \fIport\fR"
True if the packet has a source port value of \fIport\fP.
.IP "\fBport \fIport\fR"
True if either the source or destination port of the packet is \fIport\fP.
Any of the above port expressions can be prepended with the keywords,
\fBtcp\fP or \fBudp\fP, as in:
.in +.5i
.nf
\fBtcp src port \fIport\fR
.fi
.in -.5i
which matches only tcp packets whose source port is \fIport\fP.
.IP "\fBless \fIlength\fR"
True if the packet has a length less than or equal to \fIlength\fP.
This is equivalent to:
.in +.5i
.nf
\fBlen <= \fIlength\fP.
.fi
.in -.5i
.IP "\fBgreater \fIlength\fR"
True if the packet has a length greater than or equal to \fIlength\fP.
This is equivalent to:
.in +.5i
.nf
\fBlen >= \fIlength\fP.
.fi
.in -.5i
.IP "\fBip proto \fIprotocol\fR"
"iso" is *not* a qualifier that restricts address or port matches to a particular protocol. Document the new "clnp" ISO protocol type. Formatting nits.
2000-10-28 18:23:38 +08:00
True if the packet is an IP packet (see
Initial revision
1999-10-08 07:47:09 +08:00
.IR ip (4P))
of protocol type \fIprotocol\fP.
\fIProtocol\fP can be a number or one of the names
Tony Li's changes, from FreeBSD, to support filtering for OSI packets and for ESIS and ISIS packets. Don't describe "atalk", "aarp", "lat", "sca", "moprc", or "mopdl" as qualifiers that restrict address or port matches to a particular protocol, as they aren't. "iso", however, is a qualifier that applies to "proto", at least, and can take a number or "esis" or "isis" as arguments; "esis" and "isis" are short for "iso proto esis" and "iso proto isis". Update the enumeration of the protocols that can be the target of "ip proto" to reflect current reality. Enumerate all the protocols that can be the target of "ether proto", including the new "iso".
2000-10-28 18:10:54 +08:00
\fIicmp\fP, \fIicmp6\fP, \fIigmp\fP, \fIigrp\fP, \fIpim\fP, \fIah\fP,
Update the documentation to note that "vrrp" is supported in "ip proto". Fix some typos.
2001-02-21 17:40:42 +08:00
\fIesp\fP, \fIvrrp\fP, \fIudp\fP, or \fItcp\fP.
Initial revision
1999-10-08 07:47:09 +08:00
Note that the identifiers \fItcp\fP, \fIudp\fP, and \fIicmp\fP are also
keywords and must be escaped via backslash (\\), which is \\\\ in the C-shell.
Update the documentation to note that "vrrp" is supported in "ip proto". Fix some typos.
2001-02-21 17:40:42 +08:00
Note that this primitive does not chase the protocol header chain.
Bring in KAME IPv6 tcpdump. replaces esp/ah/isakmp decoder. Hope I did not break anything. Portability on IPv4-only node needs checking, I'll do this very soon. (sorry for rather jumbo commit) XXx what is _FAVOR_BSD?
1999-10-30 13:11:06 +08:00
.IP "\fBip6 proto \fIprotocol\fR"
True if the packet is an IPv6 packet of protocol type \fIprotocol\fP.
Update the documentation to note that "vrrp" is supported in "ip proto". Fix some typos.
2001-02-21 17:40:42 +08:00
Note that this primitive does not chase the protocol header chain.
Bring in KAME IPv6 tcpdump. replaces esp/ah/isakmp decoder. Hope I did not break anything. Portability on IPv4-only node needs checking, I'll do this very soon. (sorry for rather jumbo commit) XXx what is _FAVOR_BSD?
1999-10-30 13:11:06 +08:00
.IP "\fBip6 protochain \fIprotocol\fR"
True if the packet is IPv6 packet,
and contains protocol header with type \fIprotocol\fR
in its protocol header chain.
For example,
.in +.5i
.nf
\fBip6 protochain 6\fR
.fi
.in -.5i
matches any IPv6 packet with TCP protocol header in the protocol header chain.
The packet may contain, for example,
authentication header, routing header, or hop-by-hop option header,
between IPv6 header and TCP header.
The BPF code emitted by this primitive is complex and
cannot be optimized by BPF optimizer code in \fItcpdump\fP,
so this can be somewhat slow.
.IP "\fBip protochain \fIprotocol\fR"
Equivalent to \fBip6 protochain \fIprotocol\fR, but this is for IPv4.
Initial revision
1999-10-08 07:47:09 +08:00
.IP "\fBether broadcast\fR"
break line after sentence, nroff cleanup
2001-06-25 11:18:27 +08:00
True if the packet is an ethernet broadcast packet.
The \fIether\fP
Initial revision
1999-10-08 07:47:09 +08:00
keyword is optional.
.IP "\fBip broadcast\fR"
break line after sentence, nroff cleanup
2001-06-25 11:18:27 +08:00
True if the packet is an IP broadcast packet.
It checks for both
Initial revision
1999-10-08 07:47:09 +08:00
the all-zeroes and all-ones broadcast conventions, and looks up
the local subnet mask.
.IP "\fBether multicast\fR"
break line after sentence, nroff cleanup
2001-06-25 11:18:27 +08:00
True if the packet is an ethernet multicast packet.
The \fIether\fP
Initial revision
1999-10-08 07:47:09 +08:00
keyword is optional.
This is shorthand for `\fBether[0] & 1 != 0\fP'.
.IP "\fBip multicast\fR"
True if the packet is an IP multicast packet.
Bring in KAME IPv6 tcpdump. replaces esp/ah/isakmp decoder. Hope I did not break anything. Portability on IPv4-only node needs checking, I'll do this very soon. (sorry for rather jumbo commit) XXx what is _FAVOR_BSD?
1999-10-30 13:11:06 +08:00
.IP "\fBip6 multicast\fR"
True if the packet is an IPv6 multicast packet.
Initial revision
1999-10-08 07:47:09 +08:00
.IP "\fBether proto \fIprotocol\fR"
True if the packet is of ether type \fIprotocol\fR.
Tony Li's changes, from FreeBSD, to support filtering for OSI packets and for ESIS and ISIS packets. Don't describe "atalk", "aarp", "lat", "sca", "moprc", or "mopdl" as qualifiers that restrict address or port matches to a particular protocol, as they aren't. "iso", however, is a qualifier that applies to "proto", at least, and can take a number or "esis" or "isis" as arguments; "esis" and "isis" are short for "iso proto esis" and "iso proto isis". Update the enumeration of the protocols that can be the target of "ip proto" to reflect current reality. Enumerate all the protocols that can be the target of "ether proto", including the new "iso".
2000-10-28 18:10:54 +08:00
\fIProtocol\fP can be a number or one of the names
\fIip\fP, \fIip6\fP, \fIarp\fP, \fIrarp\fP, \fIatalk\fP, \fIaarp\fP,
Document the new "stp" protocol type in filter expressions. Make the explanation of the "ether <proto>" expression more completely explain the various cases.
2001-01-14 13:03:42 +08:00
\fIdecnet\fP, \fIsca\fP, \fIlat\fP, \fImopdl\fP, \fImoprc\fP,
Document the "netbeui" filter expression keyword. Add a #define LLCSAP_NETBEUI for the NetBEUI LLC SAP, and use that rather than "0xf0" in the LLC dissector.
2001-01-28 17:46:42 +08:00
\fIiso\fP, \fIstp\fP, \fIipx\fP, or \fInetbeui\fP.
Initial revision
1999-10-08 07:47:09 +08:00
Note these identifiers are also keywords
and must be escaped via backslash (\\).
Document the new "stp" protocol type in filter expressions. Make the explanation of the "ether <proto>" expression more completely explain the various cases.
2001-01-14 13:03:42 +08:00
.IP
[In the case of FDDI (e.g., `\fBfddi protocol arp\fR') and Token Ring
(e.g., `\fBtr protocol arp\fR'), for most of those protocols, the
protocol identification comes from the 802.2 Logical Link Control (LLC)
header, which is usually layered on top of the FDDI or Token Ring
header.
.IP
Document the "netbeui" filter expression keyword. Add a #define LLCSAP_NETBEUI for the NetBEUI LLC SAP, and use that rather than "0xf0" in the LLC dissector.
2001-01-28 17:46:42 +08:00
When filtering for most protocol identifiers on FDDI or Token Ring,
Expand the introductory discussion to: note at the beginning that tcpdump can write to a save file rather than printing a dissection of the packet, and can read from a saved file rather than from a network interrface; indicate what causes tcpdump to stop capturing (i.e., that, unless you've run it with "-c", you have to ^C or "kill" it); discuss the meanings of the packet counts it prints; indicate that ^T can be used on some OSes to get those packet counts while a capture is in progress; note that the special privileges required on various OSes are required only when capturing packets, not when reading a saved capture file; note that on at least some versions of Solaris you apparently have to be root in order to do a promiscuous capture. Consistently use italics to mark tcpdump's name.
2001-07-06 06:58:29 +08:00
\fItcpdump\fR checks only the protocol ID field of an LLC header in
Document the new "stp" protocol type in filter expressions. Make the explanation of the "ether <proto>" expression more completely explain the various cases.
2001-01-14 13:03:42 +08:00
so-called SNAP format with an Organizational Unit Identifier (OUI) of
0x000000, for encapsulated Ethernet; it doesn't check whether the packet
is in SNAP format with an OUI of 0x000000.
.IP
The exceptions are \fIiso\fP, for which it checks the DSAP (Destination
Service Access Point) and SSAP (Source Service Access Point) fields of
Document the "netbeui" filter expression keyword. Add a #define LLCSAP_NETBEUI for the NetBEUI LLC SAP, and use that rather than "0xf0" in the LLC dissector.
2001-01-28 17:46:42 +08:00
the LLC header, \fIstp\fP and \fInetbeui\fP, where it checks the DSAP of
the LLC header, and \fIatalk\fP, where it checks for a SNAP-format
packet with an OUI of 0x080007 and the Appletalk etype.
Document the new "stp" protocol type in filter expressions. Make the explanation of the "ether <proto>" expression more completely explain the various cases.
2001-01-14 13:03:42 +08:00
.IP
Expand the introductory discussion to: note at the beginning that tcpdump can write to a save file rather than printing a dissection of the packet, and can read from a saved file rather than from a network interrface; indicate what causes tcpdump to stop capturing (i.e., that, unless you've run it with "-c", you have to ^C or "kill" it); discuss the meanings of the packet counts it prints; indicate that ^T can be used on some OSes to get those packet counts while a capture is in progress; note that the special privileges required on various OSes are required only when capturing packets, not when reading a saved capture file; note that on at least some versions of Solaris you apparently have to be root in order to do a promiscuous capture. Consistently use italics to mark tcpdump's name.
2001-07-06 06:58:29 +08:00
In the case of Ethernet, \fItcpdump\fR checks the Ethernet type field
Document the "netbeui" filter expression keyword. Add a #define LLCSAP_NETBEUI for the NetBEUI LLC SAP, and use that rather than "0xf0" in the LLC dissector.
2001-01-28 17:46:42 +08:00
for most of those protocols; the exceptions are \fIiso\fP, \fIsap\fP,
and \fInetbeui\fP, for which it checks for an 802.3 frame and then
checks the LLC header as it does for FDDI and Token Ring, \fIatalk\fP,
where it checks both for the Appletalk etype in an Ethernet frame and
for a SNAP-format packet as it does for FDDI and Token Ring, \fIaarp\fP,
where it checks for the Appletalk ARP etype in either an Ethernet frame
or an 802.2 SNAP frame with an OUI of 0x000000, and \fIipx\fP, where it
checks for the IPX etype in an Ethernet frame, the IPX DSAP in the LLC
header, the 802.3 with no LLC header encapsulation of IPX, and the IPX
etype in a SNAP frame.]
Initial revision
1999-10-08 07:47:09 +08:00
.IP "\fBdecnet src \fIhost\fR"
True if the DECNET source address is
.IR host ,
which may be an address of the form ``10.123'', or a DECNET host
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name.
[DECNET host name support is only available on Ultrix systems
Initial revision
1999-10-08 07:47:09 +08:00
that are configured to run DECNET.]
.IP "\fBdecnet dst \fIhost\fR"
True if the DECNET destination address is
.IR host .
.IP "\fBdecnet host \fIhost\fR"
True if either the DECNET source or destination address is
.IR host .
Document the "netbeui" filter expression keyword. Add a #define LLCSAP_NETBEUI for the NetBEUI LLC SAP, and use that rather than "0xf0" in the LLC dissector.
2001-01-28 17:46:42 +08:00
.IP "\fBip\fR, \fBip6\fR, \fBarp\fR, \fBrarp\fR, \fBatalk\fR, \fBaarp\fR, \fBdecnet\fR, \fBiso\fR, \fBstp\fR, \fBipx\fR, \fInetbeui\fP"
Initial revision
1999-10-08 07:47:09 +08:00
Abbreviations for:
.in +.5i
.nf
\fBether proto \fIp\fR
.fi
.in -.5i
where \fIp\fR is one of the above protocols.
I lied - we *do* dissect IPX frames, it turns out. Update the description of "ether proto" to explain all the stuff we do to check for IPX frames.
2001-01-15 05:04:45 +08:00
.IP "\fBlat\fR, \fBmoprc\fR, \fBmopdl\fR"
Initial revision
1999-10-08 07:47:09 +08:00
Abbreviations for:
.in +.5i
.nf
\fBether proto \fIp\fR
.fi
.in -.5i
where \fIp\fR is one of the above protocols.
Note that
\fItcpdump\fP does not currently know how to parse these protocols.
Improved VLAN support, from Peter Jeremy - "vlan" filtering keyword, letting you filter based on the VLAN to which a packet belongs, and an improvement to the printing of VLAN packets (adding an extra space to separate the VLAN priority and flags from the next stuff printed).
2000-10-22 12:17:52 +08:00
.IP "\fBvlan \fI[vlan_id]\fR"
True if the packet is an IEEE 802.1Q VLAN packet.
If \fI[vlan_id]\fR is specified, only true is the packet has the specified
\fIvlan_id\fR.
Note that the first \fBvlan\fR keyword encountered in \fIexpression\fR
changes the decoding offsets for the remainder of \fIexpression\fR
on the assumption that the packet is a VLAN packet.
Initial revision
1999-10-08 07:47:09 +08:00
.IP "\fBtcp\fR, \fBudp\fR, \fBicmp\fR"
Abbreviations for:
.in +.5i
.nf
Bring in KAME IPv6 tcpdump. replaces esp/ah/isakmp decoder. Hope I did not break anything. Portability on IPv4-only node needs checking, I'll do this very soon. (sorry for rather jumbo commit) XXx what is _FAVOR_BSD?
1999-10-30 13:11:06 +08:00
\fBip proto \fIp\fR\fB or ip6 proto \fIp\fR
Initial revision
1999-10-08 07:47:09 +08:00
.fi
.in -.5i
where \fIp\fR is one of the above protocols.
Tony Li's changes, from FreeBSD, to support filtering for OSI packets and for ESIS and ISIS packets. Don't describe "atalk", "aarp", "lat", "sca", "moprc", or "mopdl" as qualifiers that restrict address or port matches to a particular protocol, as they aren't. "iso", however, is a qualifier that applies to "proto", at least, and can take a number or "esis" or "isis" as arguments; "esis" and "isis" are short for "iso proto esis" and "iso proto isis". Update the enumeration of the protocols that can be the target of "ip proto" to reflect current reality. Enumerate all the protocols that can be the target of "ether proto", including the new "iso".
2000-10-28 18:10:54 +08:00
.IP "\fBiso proto \fIprotocol\fR"
True if the packet is an OSI packet of protocol type \fIprotocol\fP.
\fIProtocol\fP can be a number or one of the names
"iso" is *not* a qualifier that restricts address or port matches to a particular protocol. Document the new "clnp" ISO protocol type. Formatting nits.
2000-10-28 18:23:38 +08:00
\fIclnp\fP, \fIesis\fP, or \fIisis\fP.
.IP "\fBclnp\fR, \fBesis\fR, \fBisis\fR"
Tony Li's changes, from FreeBSD, to support filtering for OSI packets and for ESIS and ISIS packets. Don't describe "atalk", "aarp", "lat", "sca", "moprc", or "mopdl" as qualifiers that restrict address or port matches to a particular protocol, as they aren't. "iso", however, is a qualifier that applies to "proto", at least, and can take a number or "esis" or "isis" as arguments; "esis" and "isis" are short for "iso proto esis" and "iso proto isis". Update the enumeration of the protocols that can be the target of "ip proto" to reflect current reality. Enumerate all the protocols that can be the target of "ether proto", including the new "iso".
2000-10-28 18:10:54 +08:00
Abbreviations for:
.in +.5i
.nf
\fBiso proto \fIp\fR
.fi
.in -.5i
where \fIp\fR is one of the above protocols.
Note that \fItcpdump\fR does an incomplete job of parsing these protocols.
Initial revision
1999-10-08 07:47:09 +08:00
.IP "\fIexpr relop expr\fR"
True if the relation holds, where \fIrelop\fR is one of >, <, >=, <=, =, !=,
and \fIexpr\fR is an arithmetic expression composed of integer constants
(expressed in standard C syntax), the normal binary operators
[+, -, *, /, &, |], a length operator, and special packet data accessors.
To access
data inside the packet, use the following syntax:
.in +.5i
.nf
\fIproto\fB [ \fIexpr\fB : \fIsize\fB ]\fR
.fi
.in -.5i
Document "ppp", "slip", and "link" as references to the link layer protocol in "expr relop expr" expressions.
2002-01-25 13:27:27 +08:00
\fIProto\fR is one of \fBether, fddi, tr, ppp, slip, link,
Bring in KAME IPv6 tcpdump. replaces esp/ah/isakmp decoder. Hope I did not break anything. Portability on IPv4-only node needs checking, I'll do this very soon. (sorry for rather jumbo commit) XXx what is _FAVOR_BSD?
1999-10-30 13:11:06 +08:00
ip, arp, rarp, tcp, udp, icmp\fR or \fBip6\fR, and
Initial revision
1999-10-08 07:47:09 +08:00
indicates the protocol layer for the index operation.
Document "ppp", "slip", and "link" as references to the link layer protocol in "expr relop expr" expressions.
2002-01-25 13:27:27 +08:00
(\fBether, fddi, tr, ppp, slip\fR and \fBlink\fR all refer to the link
layer.)
Bring in KAME IPv6 tcpdump. replaces esp/ah/isakmp decoder. Hope I did not break anything. Portability on IPv4-only node needs checking, I'll do this very soon. (sorry for rather jumbo commit) XXx what is _FAVOR_BSD?
1999-10-30 13:11:06 +08:00
Note that \fItcp, udp\fR and other upper-layer protocol types only
apply to IPv4, not IPv6 (this will be fixed in the future).
Initial revision
1999-10-08 07:47:09 +08:00
The byte offset, relative to the indicated protocol layer, is
given by \fIexpr\fR.
\fISize\fR is optional and indicates the number of bytes in the
field of interest; it can be either one, two, or four, and defaults to one.
The length operator, indicated by the keyword \fBlen\fP, gives the
length of the packet.
For example, `\fBether[0] & 1 != 0\fP' catches all multicast traffic.
The expression `\fBip[0] & 0xf != 5\fP'
break line after sentence, nroff cleanup
2001-06-25 11:18:27 +08:00
catches all IP packets with options.
The expression
Initial revision
1999-10-08 07:47:09 +08:00
`\fBip[6:2] & 0x1fff = 0\fP'
catches only unfragmented datagrams and frag zero of fragmented datagrams.
This check is implicitly applied to the \fBtcp\fP and \fBudp\fP
index operations.
For instance, \fBtcp[0]\fP always means the first
byte of the TCP \fIheader\fP, and never means the first byte of an
intervening fragment.
Jason Thorpe's changes from NetBSD, to document the symbolic names that can be used for checking ICMP types, ICMP codes, and TCP flags.
2001-02-25 09:00:25 +08:00
Some offsets and field values may be expressed as names rather than
break line after sentence, nroff cleanup
2001-06-25 11:18:27 +08:00
as numeric values.
The following protocol header field offsets are
Jason Thorpe's changes from NetBSD, to document the symbolic names that can be used for checking ICMP types, ICMP codes, and TCP flags.
2001-02-25 09:00:25 +08:00
available: \fBicmptype\fP (ICMP type field), \fBicmpcode\fP (ICMP
code field), and \fBtcpflags\fP (TCP flags field).
The following ICMP type field values are available: \fBicmp-echoreply\fP,
\fBicmp-unreach\fP, \fBicmp-sourcequench\fP, \fBicmp-redirect\fP,
\fBicmp-echo\fP, \fBicmp-routeradvert\fP, \fBicmp-routersolicit\fP,
\fBicmp-timxceed\fP, \fBicmp-paramprob\fP, \fBicmp-tstamp\fP,
\fBicmp-tstampreply\fP, \fBicmp-ireq\fP, \fBicmp-ireqreply\fP,
\fBicmp-maskreq\fP, \fBicmp-maskreply\fP.
The following TCP flags field values are available: \fBtcp-fin\fP,
\fBtcp-syn\fP, \fBtcp-rst\fP, \fBtcp-push\fP, \fBtcp-push\fP,
\fBtcp-ack\fP, \fBtcp-urg\fP.
Initial revision
1999-10-08 07:47:09 +08:00
.LP
Primitives may be combined using:
.IP
A parenthesized group of primitives and operators
(parentheses are special to the Shell and must be escaped).
.IP
Negation (`\fB!\fP' or `\fBnot\fP').
.IP
Concatenation (`\fB&&\fP' or `\fBand\fP').
.IP
Alternation (`\fB||\fP' or `\fBor\fP').
.LP
Negation has highest precedence.
Alternation and concatenation have equal precedence and associate
break line after sentence, nroff cleanup
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left to right.
Note that explicit \fBand\fR tokens, not juxtaposition,
Initial revision
1999-10-08 07:47:09 +08:00
are now required for concatenation.
.LP
If an identifier is given without a keyword, the most recent keyword
is assumed.
For example,
.in +.5i
.nf
\fBnot host vs and ace\fR
.fi
.in -.5i
is short for
.in +.5i
.nf
\fBnot host vs and host ace\fR
.fi
.in -.5i
which should not be confused with
.in +.5i
.nf
\fBnot ( host vs or ace )\fR
.fi
.in -.5i
.LP
Add documentation for Token Ring. Change some font choices to match the conventions used historically in this man page (use boldface for literal strings, italics for variables, and italics for "tcpdump" when it refers to the name of the program).
2000-07-25 14:09:32 +08:00
Expression arguments can be passed to \fItcpdump\fP as either a single
argument or as multiple arguments, whichever is more convenient.
Initial revision
1999-10-08 07:47:09 +08:00
Generally, if the expression contains Shell metacharacters, it is
easier to pass it as a single, quoted argument.
Multiple arguments are concatenated with spaces before being parsed.
.SH EXAMPLES
.LP
To print all packets arriving at or departing from \fIsundown\fP:
.RS
.nf
\fBtcpdump host sundown\fP
.fi
.RE
.LP
To print traffic between \fIhelios\fR and either \fIhot\fR or \fIace\fR:
.RS
.nf
\fBtcpdump host helios and \\( hot or ace \\)\fP
.fi
.RE
.LP
To print all IP packets between \fIace\fR and any host except \fIhelios\fR:
.RS
.nf
\fBtcpdump ip host ace and not helios\fP
.fi
.RE
.LP
To print all traffic between local hosts and hosts at Berkeley:
.RS
.nf
.B
tcpdump net ucb-ether
.fi
.RE
.LP
To print all ftp traffic through internet gateway \fIsnup\fP:
(note that the expression is quoted to prevent the shell from
(mis-)interpreting the parentheses):
.RS
.nf
.B
tcpdump 'gateway snup and (port ftp or ftp-data)'
.fi
.RE
.LP
To print traffic neither sourced from nor destined for local hosts
(if you gateway to one other net, this stuff should never make it
onto your local net).
.RS
.nf
.B
tcpdump ip and not net \fIlocalnet\fP
.fi
.RE
.LP
To print the start and end packets (the SYN and FIN packets) of each
TCP conversation that involves a non-local host.
.RS
.nf
.B
Jason Thorpe's changes from NetBSD, to document the symbolic names that can be used for checking ICMP types, ICMP codes, and TCP flags.
2001-02-25 09:00:25 +08:00
tcpdump 'tcp[tcpflags] & (tcp-syn|tcp-fin) != 0 and not src and dst net \fIlocalnet\fP'
Initial revision
1999-10-08 07:47:09 +08:00
.fi
.RE
.LP
To print IP packets longer than 576 bytes sent through gateway \fIsnup\fP:
.RS
.nf
.B
tcpdump 'gateway snup and ip[2:2] > 576'
.fi
.RE
.LP
To print IP broadcast or multicast packets that were
.I not
sent via ethernet broadcast or multicast:
.RS
.nf
.B
tcpdump 'ether[0] & 1 = 0 and ip[16] >= 224'
.fi
.RE
.LP
To print all ICMP packets that are not echo requests/replies (i.e., not
ping packets):
.RS
.nf
.B
Jason Thorpe's changes from NetBSD, to document the symbolic names that can be used for checking ICMP types, ICMP codes, and TCP flags.
2001-02-25 09:00:25 +08:00
tcpdump 'icmp[icmptype] != icmp-echo and icmp[icmptype] != icmp-echoreply'
Initial revision
1999-10-08 07:47:09 +08:00
.fi
.RE
.SH OUTPUT FORMAT
.LP
break line after sentence, nroff cleanup
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The output of \fItcpdump\fP is protocol dependent.
The following
Initial revision
1999-10-08 07:47:09 +08:00
gives a brief description and examples of most of the formats.
.de HD
.sp 1.5
.B
..
.HD
Link Level Headers
.LP
If the '-e' option is given, the link level header is printed out.
On ethernets, the source and destination addresses, protocol,
and packet length are printed.
.LP
On FDDI networks, the '-e' option causes \fItcpdump\fP to print
the `frame control' field, the source and destination addresses,
break line after sentence, nroff cleanup
2001-06-25 11:18:27 +08:00
and the packet length.
(The `frame control' field governs the
interpretation of the rest of the packet.
Normal packets (such
Initial revision
1999-10-08 07:47:09 +08:00
as those containing IP datagrams) are `async' packets, with a priority
break line after sentence, nroff cleanup
2001-06-25 11:18:27 +08:00
value between 0 and 7; for example, `\fBasync4\fR'.
Such packets
Initial revision
1999-10-08 07:47:09 +08:00
are assumed to contain an 802.2 Logical Link Control (LLC) packet;
the LLC header is printed if it is \fInot\fR an ISO datagram or a
so-called SNAP packet.
.LP
Add documentation for Token Ring. Change some font choices to match the conventions used historically in this man page (use boldface for literal strings, italics for variables, and italics for "tcpdump" when it refers to the name of the program).
2000-07-25 14:09:32 +08:00
On Token Ring networks, the '-e' option causes \fItcpdump\fP to print
the `access control' and `frame control' fields, the source and
break line after sentence, nroff cleanup
2001-06-25 11:18:27 +08:00
destination addresses, and the packet length.
As on FDDI networks,
packets are assumed to contain an LLC packet.
Regardless of whether
Add documentation for Token Ring. Change some font choices to match the conventions used historically in this man page (use boldface for literal strings, italics for variables, and italics for "tcpdump" when it refers to the name of the program).
2000-07-25 14:09:32 +08:00
the '-e' option is specified or not, the source routing information is
printed for source-routed packets.
.LP
Initial revision
1999-10-08 07:47:09 +08:00
\fI(N.B.: The following description assumes familiarity with
the SLIP compression algorithm described in RFC-1144.)\fP
.LP
On SLIP links, a direction indicator (``I'' for inbound, ``O'' for outbound),
packet type, and compression information are printed out.
The packet type is printed first.
The three types are \fIip\fP, \fIutcp\fP, and \fIctcp\fP.
No further link information is printed for \fIip\fR packets.
For TCP packets, the connection identifier is printed following the type.
If the packet is compressed, its encoded header is printed out.
The special cases are printed out as
\fB*S+\fIn\fR and \fB*SA+\fIn\fR, where \fIn\fR is the amount by which
the sequence number (or sequence number and ack) has changed.
If it is not a special case,
zero or more changes are printed.
A change is indicated by U (urgent pointer), W (window), A (ack),
S (sequence number), and I (packet ID), followed by a delta (+n or -n),
or a new value (=n).
Finally, the amount of data in the packet and compressed header length
are printed.
.LP
For example, the following line shows an outbound compressed TCP packet,
with an implicit connection identifier; the ack has changed by 6,
the sequence number by 49, and the packet ID by 6; there are 3 bytes of
data and 6 bytes of compressed header:
.RS
.nf
\fBO ctcp * A+6 S+49 I+6 3 (6)\fP
.fi
.RE
.HD
ARP/RARP Packets
.LP
break line after sentence, nroff cleanup
2001-06-25 11:18:27 +08:00
Arp/rarp output shows the type of request and its arguments.
The
Initial revision
1999-10-08 07:47:09 +08:00
format is intended to be self explanatory.
Here is a short sample taken from the start of an `rlogin' from
host \fIrtsg\fP to host \fIcsam\fP:
.RS
.nf
.sp .5
\f(CWarp who-has csam tell rtsg
Make the introductory section of the README file use the same style as the introductory README section of the libpcap README file, giving information about anonymous CVS and other additional information. Update to note that non-patch mail should be sent to "tcpdump-workers@tcpdump.org", and that patches should be sent to "patches@tcpdump.org". Merge in changes from the tcpdump 3.5 branch: "\f(CW" doesn't work on all systems - which appears to cause a subsequent "\fP" to revert to the font from which *roff last switched, which is often an italic or boldface font. Use "\fR" instead of "\fP" to undo a "\f(CW". and other changes not in the main line.
2000-07-13 14:36:57 +08:00
arp reply csam is-at CSAM\fR
Initial revision
1999-10-08 07:47:09 +08:00
.sp .5
.fi
.RE
The first line says that rtsg sent an arp packet asking
break line after sentence, nroff cleanup
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for the ethernet address of internet host csam.
Csam
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replies with its ethernet address (in this example, ethernet addresses
are in caps and internet addresses in lower case).
.LP
Expand the introductory discussion to: note at the beginning that tcpdump can write to a save file rather than printing a dissection of the packet, and can read from a saved file rather than from a network interrface; indicate what causes tcpdump to stop capturing (i.e., that, unless you've run it with "-c", you have to ^C or "kill" it); discuss the meanings of the packet counts it prints; indicate that ^T can be used on some OSes to get those packet counts while a capture is in progress; note that the special privileges required on various OSes are required only when capturing packets, not when reading a saved capture file; note that on at least some versions of Solaris you apparently have to be root in order to do a promiscuous capture. Consistently use italics to mark tcpdump's name.
2001-07-06 06:58:29 +08:00
This would look less redundant if we had done \fItcpdump \-n\fP:
Initial revision
1999-10-08 07:47:09 +08:00
.RS
.nf
.sp .5
\f(CWarp who-has 128.3.254.6 tell 128.3.254.68
arp reply 128.3.254.6 is-at 02:07:01:00:01:c4\fP
.fi
.RE
.LP
Expand the introductory discussion to: note at the beginning that tcpdump can write to a save file rather than printing a dissection of the packet, and can read from a saved file rather than from a network interrface; indicate what causes tcpdump to stop capturing (i.e., that, unless you've run it with "-c", you have to ^C or "kill" it); discuss the meanings of the packet counts it prints; indicate that ^T can be used on some OSes to get those packet counts while a capture is in progress; note that the special privileges required on various OSes are required only when capturing packets, not when reading a saved capture file; note that on at least some versions of Solaris you apparently have to be root in order to do a promiscuous capture. Consistently use italics to mark tcpdump's name.
2001-07-06 06:58:29 +08:00
If we had done \fItcpdump \-e\fP, the fact that the first packet is
Initial revision
1999-10-08 07:47:09 +08:00
broadcast and the second is point-to-point would be visible:
.RS
.nf
.sp .5
\f(CWRTSG Broadcast 0806 64: arp who-has csam tell rtsg
Make the introductory section of the README file use the same style as the introductory README section of the libpcap README file, giving information about anonymous CVS and other additional information. Update to note that non-patch mail should be sent to "tcpdump-workers@tcpdump.org", and that patches should be sent to "patches@tcpdump.org". Merge in changes from the tcpdump 3.5 branch: "\f(CW" doesn't work on all systems - which appears to cause a subsequent "\fP" to revert to the font from which *roff last switched, which is often an italic or boldface font. Use "\fR" instead of "\fP" to undo a "\f(CW". and other changes not in the main line.
2000-07-13 14:36:57 +08:00
CSAM RTSG 0806 64: arp reply csam is-at CSAM\fR
Initial revision
1999-10-08 07:47:09 +08:00
.sp .5
.fi
.RE
For the first packet this says the ethernet source address is RTSG, the
destination is the ethernet broadcast address, the type field
contained hex 0806 (type ETHER_ARP) and the total length was 64 bytes.
.HD
TCP Packets
.LP
\fI(N.B.:The following description assumes familiarity with
break line after sentence, nroff cleanup
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the TCP protocol described in RFC-793.
If you are not familiar
Add documentation for Token Ring. Change some font choices to match the conventions used historically in this man page (use boldface for literal strings, italics for variables, and italics for "tcpdump" when it refers to the name of the program).
2000-07-25 14:09:32 +08:00
with the protocol, neither this description nor \fItcpdump\fP will
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be of much use to you.)\fP
.LP
The general format of a tcp protocol line is:
.RS
.nf
.sp .5
\fIsrc > dst: flags data-seqno ack window urgent options\fP
.sp .5
.fi
.RE
\fISrc\fP and \fIdst\fP are the source and destination IP
break line after sentence, nroff cleanup
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addresses and ports.
\fIFlags\fP are some combination of S (SYN),
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F (FIN), P (PUSH) or R (RST) or a single `.' (no flags).
\fIData-seqno\fP describes the portion of sequence space covered
by the data in this packet (see example below).
\fIAck\fP is sequence number of the next data expected the other
direction on this connection.
\fIWindow\fP is the number of bytes of receive buffer space available
the other direction on this connection.
\fIUrg\fP indicates there is `urgent' data in the packet.
\fIOptions\fP are tcp options enclosed in angle brackets (e.g., <mss 1024>).
.LP
break line after sentence, nroff cleanup
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\fISrc, dst\fP and \fIflags\fP are always present.
The other fields
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depend on the contents of the packet's tcp protocol header and
are output only if appropriate.
.LP
Here is the opening portion of an rlogin from host \fIrtsg\fP to
host \fIcsam\fP.
.RS
.nf
.sp .5
\s-2\f(CWrtsg.1023 > csam.login: S 768512:768512(0) win 4096 <mss 1024>
csam.login > rtsg.1023: S 947648:947648(0) ack 768513 win 4096 <mss 1024>
rtsg.1023 > csam.login: . ack 1 win 4096
rtsg.1023 > csam.login: P 1:2(1) ack 1 win 4096
csam.login > rtsg.1023: . ack 2 win 4096
rtsg.1023 > csam.login: P 2:21(19) ack 1 win 4096
csam.login > rtsg.1023: P 1:2(1) ack 21 win 4077
csam.login > rtsg.1023: P 2:3(1) ack 21 win 4077 urg 1
Make the introductory section of the README file use the same style as the introductory README section of the libpcap README file, giving information about anonymous CVS and other additional information. Update to note that non-patch mail should be sent to "tcpdump-workers@tcpdump.org", and that patches should be sent to "patches@tcpdump.org". Merge in changes from the tcpdump 3.5 branch: "\f(CW" doesn't work on all systems - which appears to cause a subsequent "\fP" to revert to the font from which *roff last switched, which is often an italic or boldface font. Use "\fR" instead of "\fP" to undo a "\f(CW". and other changes not in the main line.
2000-07-13 14:36:57 +08:00
csam.login > rtsg.1023: P 3:4(1) ack 21 win 4077 urg 1\fR\s+2
Initial revision
1999-10-08 07:47:09 +08:00
.sp .5
.fi
.RE
The first line says that tcp port 1023 on rtsg sent a packet
to port \fIlogin\fP
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on csam.
The \fBS\fP indicates that the \fISYN\fP flag was set.
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The packet sequence number was 768512 and it contained no data.
(The notation is `first:last(nbytes)' which means `sequence
numbers \fIfirst\fP
up to but not including \fIlast\fP which is \fInbytes\fP bytes of user data'.)
There was no piggy-backed ack, the available receive window was 4096
bytes and there was a max-segment-size option requesting an mss of
1024 bytes.
.LP
Csam replies with a similar packet except it includes a piggy-backed
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ack for rtsg's SYN.
Rtsg then acks csam's SYN.
The `.' means no
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flags were set.
The packet contained no data so there is no data sequence number.
Note that the ack sequence
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number is a small integer (1).
The first time \fItcpdump\fP sees a
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tcp `conversation', it prints the sequence number from the packet.
On subsequent packets of the conversation, the difference between
the current packet's sequence number and this initial sequence number
break line after sentence, nroff cleanup
2001-06-25 11:18:27 +08:00
is printed.
This means that sequence numbers after the
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first can be interpreted
as relative byte positions in the conversation's data stream (with the
break line after sentence, nroff cleanup
2001-06-25 11:18:27 +08:00
first data byte each direction being `1').
`-S' will override this
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feature, causing the original sequence numbers to be output.
.LP
On the 6th line, rtsg sends csam 19 bytes of data (bytes 2 through 20
in the rtsg \(-> csam side of the conversation).
The PUSH flag is set in the packet.
On the 7th line, csam says it's received data sent by rtsg up to
break line after sentence, nroff cleanup
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but not including byte 21.
Most of this data is apparently sitting in the
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1999-10-08 07:47:09 +08:00
socket buffer since csam's receive window has gotten 19 bytes smaller.
Csam also sends one byte of data to rtsg in this packet.
On the 8th and 9th lines,
csam sends two bytes of urgent, pushed data to rtsg.
.LP
Add documentation for Token Ring. Change some font choices to match the conventions used historically in this man page (use boldface for literal strings, italics for variables, and italics for "tcpdump" when it refers to the name of the program).
2000-07-25 14:09:32 +08:00
If the snapshot was small enough that \fItcpdump\fP didn't capture
Initial revision
1999-10-08 07:47:09 +08:00
the full TCP header, it interprets as much of the header as it can
and then reports ``[|\fItcp\fP]'' to indicate the remainder could not
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2001-06-25 11:18:27 +08:00
be interpreted.
If the header contains a bogus option (one with a length
Add documentation for Token Ring. Change some font choices to match the conventions used historically in this man page (use boldface for literal strings, italics for variables, and italics for "tcpdump" when it refers to the name of the program).
2000-07-25 14:09:32 +08:00
that's either too small or beyond the end of the header), \fItcpdump\fP
reports it as ``[\fIbad opt\fP]'' and does not interpret any further
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2001-06-25 11:18:27 +08:00
options (since it's impossible to tell where they start).
If the header
Add documentation for Token Ring. Change some font choices to match the conventions used historically in this man page (use boldface for literal strings, italics for variables, and italics for "tcpdump" when it refers to the name of the program).
2000-07-25 14:09:32 +08:00
length indicates options are present but the IP datagram length is not
long enough for the options to actually be there, \fItcpdump\fP reports
it as ``[\fIbad hdr length\fP]''.
Initial revision
1999-10-08 07:47:09 +08:00
.HD
documentation suggestions from Toni Andjelkovic on TCP flags
2000-06-12 00:51:09 +08:00
.B Capturing TCP packets with particular flag combinations (SYN-ACK, URG-ACK, etc.)
.PP
Fix a typo in the tcpdump man page. While I'm at it, add ECN flags to TCP packet format.
2001-10-20 04:03:08 +08:00
There are 8 bits in the control bits section of the TCP header:
documentation suggestions from Toni Andjelkovic on TCP flags
2000-06-12 00:51:09 +08:00
.IP
Fix a typo in the tcpdump man page. While I'm at it, add ECN flags to TCP packet format.
2001-10-20 04:03:08 +08:00
.I CWR | ECE | URG | ACK | PSH | RST | SYN | FIN
documentation suggestions from Toni Andjelkovic on TCP flags
2000-06-12 00:51:09 +08:00
.PP
Let's assume that we want to watch packets used in establishing
break line after sentence, nroff cleanup
2001-06-25 11:18:27 +08:00
a TCP connection.
Recall that TCP uses a 3-way handshake protocol
documentation suggestions from Toni Andjelkovic on TCP flags
2000-06-12 00:51:09 +08:00
when it initializes a new connection; the connection sequence with
regard to the TCP control bits is
.PP
.RS
1) Caller sends SYN
.RE
.RS
2) Recipient responds with SYN, ACK
.RE
.RS
3) Caller sends ACK
.RE
.PP
Now we're interested in capturing packets that have only the
break line after sentence, nroff cleanup
2001-06-25 11:18:27 +08:00
SYN bit set (Step 1).
Note that we don't want packets from step 2
(SYN-ACK), just a plain initial SYN.
What we need is a correct filter
Add documentation for Token Ring. Change some font choices to match the conventions used historically in this man page (use boldface for literal strings, italics for variables, and italics for "tcpdump" when it refers to the name of the program).
2000-07-25 14:09:32 +08:00
expression for \fItcpdump\fP.
documentation suggestions from Toni Andjelkovic on TCP flags
2000-06-12 00:51:09 +08:00
.PP
Recall the structure of a TCP header without options:
.PP
.nf
0 15 31
-----------------------------------------------------------------
| source port | destination port |
-----------------------------------------------------------------
| sequence number |
-----------------------------------------------------------------
| acknowledgment number |
-----------------------------------------------------------------
Fix a typo in the tcpdump man page. While I'm at it, add ECN flags to TCP packet format.
2001-10-20 04:03:08 +08:00
| HL | rsvd |C|E|U|A|P|R|S|F| window size |
documentation suggestions from Toni Andjelkovic on TCP flags
2000-06-12 00:51:09 +08:00
-----------------------------------------------------------------
| TCP checksum | urgent pointer |
-----------------------------------------------------------------
.fi
.PP
A TCP header usually holds 20 octets of data, unless options are
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2001-06-25 11:18:27 +08:00
present.
Fix a typo in the tcpdump man page. While I'm at it, add ECN flags to TCP packet format.
2001-10-20 04:03:08 +08:00
The first line of the graph contains octets 0 - 3, the
documentation suggestions from Toni Andjelkovic on TCP flags
2000-06-12 00:51:09 +08:00
second line shows octets 4 - 7 etc.
.PP
Starting to count with 0, the relevant TCP control bits are contained
in octet 13:
.PP
.nf
0 7| 15| 23| 31
----------------|---------------|---------------|----------------
Fix a typo in the tcpdump man page. While I'm at it, add ECN flags to TCP packet format.
2001-10-20 04:03:08 +08:00
| HL | rsvd |C|E|U|A|P|R|S|F| window size |
documentation suggestions from Toni Andjelkovic on TCP flags
2000-06-12 00:51:09 +08:00
----------------|---------------|---------------|----------------
| | 13th octet | | |
.fi
.PP
Let's have a closer look at octet no. 13:
.PP
.nf
| |
|---------------|
Fix a typo in the tcpdump man page. While I'm at it, add ECN flags to TCP packet format.
2001-10-20 04:03:08 +08:00
|C|E|U|A|P|R|S|F|
documentation suggestions from Toni Andjelkovic on TCP flags
2000-06-12 00:51:09 +08:00
|---------------|
|7 5 3 0|
.fi
.PP
Fix a typo in the tcpdump man page. While I'm at it, add ECN flags to TCP packet format.
2001-10-20 04:03:08 +08:00
These are the TCP control bits we are interested
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in.
We have numbered the bits in this octet from 0 to 7, right to
documentation suggestions from Toni Andjelkovic on TCP flags
2000-06-12 00:51:09 +08:00
left, so the PSH bit is bit number 3, while the URG bit is number 5.
.PP
Recall that we want to capture packets with only SYN set.
Let's see what happens to octet 13 if a TCP datagram arrives
with the SYN bit set in its header:
.PP
.nf
Fix a typo in the tcpdump man page. While I'm at it, add ECN flags to TCP packet format.
2001-10-20 04:03:08 +08:00
|C|E|U|A|P|R|S|F|
documentation suggestions from Toni Andjelkovic on TCP flags
2000-06-12 00:51:09 +08:00
|---------------|
|0 0 0 0 0 0 1 0|
|---------------|
|7 6 5 4 3 2 1 0|
.fi
.PP
break line after sentence, nroff cleanup
2001-06-25 11:18:27 +08:00
Looking at the
documentation suggestions from Toni Andjelkovic on TCP flags
2000-06-12 00:51:09 +08:00
control bits section we see that only bit number 1 (SYN) is set.
.PP
Assuming that octet number 13 is an 8-bit unsigned integer in
network byte order, the binary value of this octet is
.IP
00000010
.PP
and its decimal representation is
.PP
.nf
7 6 5 4 3 2 1 0
0*2 + 0*2 + 0*2 + 0*2 + 0*2 + 0*2 + 1*2 + 0*2 = 2
.fi
.PP
We're almost done, because now we know that if only SYN is set,
the value of the 13th octet in the TCP header, when interpreted
as a 8-bit unsigned integer in network byte order, must be exactly 2.
.PP
This relationship can be expressed as
.RS
.B
tcp[13] == 2
.RE
.PP
Add documentation for Token Ring. Change some font choices to match the conventions used historically in this man page (use boldface for literal strings, italics for variables, and italics for "tcpdump" when it refers to the name of the program).
2000-07-25 14:09:32 +08:00
We can use this expression as the filter for \fItcpdump\fP in order
documentation suggestions from Toni Andjelkovic on TCP flags
2000-06-12 00:51:09 +08:00
to watch packets which have only SYN set:
.RS
.B
tcpdump -i xl0 tcp[13] == 2
.RE
.PP
The expression says "let the 13th octet of a TCP datagram have
the decimal value 2", which is exactly what we want.
.PP
Now, let's assume that we need to capture SYN packets, but we
don't care if ACK or any other TCP control bit is set at the
break line after sentence, nroff cleanup
2001-06-25 11:18:27 +08:00
same time.
Let's see what happens to octet 13 when a TCP datagram
documentation suggestions from Toni Andjelkovic on TCP flags
2000-06-12 00:51:09 +08:00
with SYN-ACK set arrives:
.PP
.nf
Fix a typo in the tcpdump man page. While I'm at it, add ECN flags to TCP packet format.
2001-10-20 04:03:08 +08:00
|C|E|U|A|P|R|S|F|
documentation suggestions from Toni Andjelkovic on TCP flags
2000-06-12 00:51:09 +08:00
|---------------|
|0 0 0 1 0 0 1 0|
|---------------|
|7 6 5 4 3 2 1 0|
.fi
.PP
break line after sentence, nroff cleanup
2001-06-25 11:18:27 +08:00
Now bits 1 and 4 are set in the 13th octet.
The binary value of
documentation suggestions from Toni Andjelkovic on TCP flags
2000-06-12 00:51:09 +08:00
octet 13 is
.IP
00010010
.PP
which translates to decimal
.PP
.nf
7 6 5 4 3 2 1 0
0*2 + 0*2 + 0*2 + 1*2 + 0*2 + 0*2 + 1*2 + 0*2 = 18
.fi
.PP
Add documentation for Token Ring. Change some font choices to match the conventions used historically in this man page (use boldface for literal strings, italics for variables, and italics for "tcpdump" when it refers to the name of the program).
2000-07-25 14:09:32 +08:00
Now we can't just use 'tcp[13] == 18' in the \fItcpdump\fP filter
expression, because that would select only those packets that have
break line after sentence, nroff cleanup
2001-06-25 11:18:27 +08:00
SYN-ACK set, but not those with only SYN set.
Remember that we don't care
documentation suggestions from Toni Andjelkovic on TCP flags
2000-06-12 00:51:09 +08:00
if ACK or any other control bit is set as long as SYN is set.
.PP
In order to achieve our goal, we need to logically AND the
binary value of octet 13 with some other value to preserve
break line after sentence, nroff cleanup
2001-06-25 11:18:27 +08:00
the SYN bit.
We know that we want SYN to be set in any case,
documentation suggestions from Toni Andjelkovic on TCP flags
2000-06-12 00:51:09 +08:00
so we'll logically AND the value in the 13th octet with
the binary value of a SYN:
.PP
.nf
00010010 SYN-ACK 00000010 SYN
AND 00000010 (we want SYN) AND 00000010 (we want SYN)
-------- --------
= 00000010 = 00000010
.fi
.PP
We see that this AND operation delivers the same result
regardless whether ACK or another TCP control bit is set.
The decimal representation of the AND value as well as
the result of this operation is 2 (binary 00000010),
so we know that for packets with SYN set the following
relation must hold true:
.IP
( ( value of octet 13 ) AND ( 2 ) ) == ( 2 )
.PP
Add documentation for Token Ring. Change some font choices to match the conventions used historically in this man page (use boldface for literal strings, italics for variables, and italics for "tcpdump" when it refers to the name of the program).
2000-07-25 14:09:32 +08:00
This points us to the \fItcpdump\fP filter expression
documentation suggestions from Toni Andjelkovic on TCP flags
2000-06-12 00:51:09 +08:00
.RS
.B
tcpdump -i xl0 'tcp[13] & 2 == 2'
.RE
.PP
Note that you should use single quotes or a backslash
in the expression to hide the AND ('&') special character
from the shell.
.HD
Initial revision
1999-10-08 07:47:09 +08:00
.B
UDP Packets
.LP
UDP format is illustrated by this rwho packet:
.RS
.nf
.sp .5
\f(CWactinide.who > broadcast.who: udp 84\fP
.sp .5
.fi
.RE
This says that port \fIwho\fP on host \fIactinide\fP sent a udp
datagram to port \fIwho\fP on host \fIbroadcast\fP, the Internet
break line after sentence, nroff cleanup
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broadcast address.
The packet contained 84 bytes of user data.
Initial revision
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.LP
Some UDP services are recognized (from the source or destination
port number) and the higher level protocol information printed.
In particular, Domain Name service requests (RFC-1034/1035) and Sun
RPC calls (RFC-1050) to NFS.
.HD
UDP Name Server Requests
.LP
\fI(N.B.:The following description assumes familiarity with
break line after sentence, nroff cleanup
2001-06-25 11:18:27 +08:00
the Domain Service protocol described in RFC-1035.
If you are not familiar
Initial revision
1999-10-08 07:47:09 +08:00
with the protocol, the following description will appear to be written
in greek.)\fP
.LP
Name server requests are formatted as
.RS
.nf
.sp .5
\fIsrc > dst: id op? flags qtype qclass name (len)\fP
.sp .5
Make the introductory section of the README file use the same style as the introductory README section of the libpcap README file, giving information about anonymous CVS and other additional information. Update to note that non-patch mail should be sent to "tcpdump-workers@tcpdump.org", and that patches should be sent to "patches@tcpdump.org". Merge in changes from the tcpdump 3.5 branch: "\f(CW" doesn't work on all systems - which appears to cause a subsequent "\fP" to revert to the font from which *roff last switched, which is often an italic or boldface font. Use "\fR" instead of "\fP" to undo a "\f(CW". and other changes not in the main line.
2000-07-13 14:36:57 +08:00
\f(CWh2opolo.1538 > helios.domain: 3+ A? ucbvax.berkeley.edu. (37)\fR
Initial revision
1999-10-08 07:47:09 +08:00
.sp .5
.fi
.RE
Host \fIh2opolo\fP asked the domain server on \fIhelios\fP for an
address record (qtype=A) associated with the name \fIucbvax.berkeley.edu.\fP
break line after sentence, nroff cleanup
2001-06-25 11:18:27 +08:00
The query id was `3'.
The `+' indicates the \fIrecursion desired\fP flag
was set.
The query length was 37 bytes, not including the UDP and
IP protocol headers.
The query operation was the normal one, \fIQuery\fP,
so the op field was omitted.
If the op had been anything else, it would
Initial revision
1999-10-08 07:47:09 +08:00
have been printed between the `3' and the `+'.
Similarly, the qclass was the normal one,
break line after sentence, nroff cleanup
2001-06-25 11:18:27 +08:00
\fIC_IN\fP, and omitted.
Any other qclass would have been printed
Initial revision
1999-10-08 07:47:09 +08:00
immediately after the `A'.
.LP
A few anomalies are checked and may result in extra fields enclosed in
The last RR section of a DNS message is the additional records section, not the authority records section, as pointed out by Lobato <lobato@pobox.com>.
2002-01-04 15:37:49 +08:00
square brackets: If a query contains an answer, authority records or
additional records section,
Initial revision
1999-10-08 07:47:09 +08:00
.IR ancount ,
.IR nscount ,
or
.I arcount
are printed as `[\fIn\fPa]', `[\fIn\fPn]' or `[\fIn\fPau]' where \fIn\fP
is the appropriate count.
If any of the response bits are set (AA, RA or rcode) or any of the
`must be zero' bits are set in bytes two and three, `[b2&3=\fIx\fP]'
is printed, where \fIx\fP is the hex value of header bytes two and three.
.HD
UDP Name Server Responses
.LP
Name server responses are formatted as
.RS
.nf
.sp .5
\fIsrc > dst: id op rcode flags a/n/au type class data (len)\fP
.sp .5
\f(CWhelios.domain > h2opolo.1538: 3 3/3/7 A 128.32.137.3 (273)
Make the introductory section of the README file use the same style as the introductory README section of the libpcap README file, giving information about anonymous CVS and other additional information. Update to note that non-patch mail should be sent to "tcpdump-workers@tcpdump.org", and that patches should be sent to "patches@tcpdump.org". Merge in changes from the tcpdump 3.5 branch: "\f(CW" doesn't work on all systems - which appears to cause a subsequent "\fP" to revert to the font from which *roff last switched, which is often an italic or boldface font. Use "\fR" instead of "\fP" to undo a "\f(CW". and other changes not in the main line.
2000-07-13 14:36:57 +08:00
helios.domain > h2opolo.1537: 2 NXDomain* 0/1/0 (97)\fR
Initial revision
1999-10-08 07:47:09 +08:00
.sp .5
.fi
.RE
In the first example, \fIhelios\fP responds to query id 3 from \fIh2opolo\fP
The last RR section of a DNS message is the additional records section, not the authority records section, as pointed out by Lobato <lobato@pobox.com>.
2002-01-04 15:37:49 +08:00
with 3 answer records, 3 name server records and 7 additional records.
Initial revision
1999-10-08 07:47:09 +08:00
The first answer record is type A (address) and its data is internet
break line after sentence, nroff cleanup
2001-06-25 11:18:27 +08:00
address 128.32.137.3.
The total size of the response was 273 bytes,
excluding UDP and IP headers.
The op (Query) and response code
Initial revision
1999-10-08 07:47:09 +08:00
(NoError) were omitted, as was the class (C_IN) of the A record.
.LP
In the second example, \fIhelios\fP responds to query 2 with a
response code of non-existent domain (NXDomain) with no answers,
break line after sentence, nroff cleanup
2001-06-25 11:18:27 +08:00
one name server and no authority records.
The `*' indicates that
the \fIauthoritative answer\fP bit was set.
Since there were no
Initial revision
1999-10-08 07:47:09 +08:00
answers, no type, class or data were printed.
.LP
Other flag characters that might appear are `\-' (recursion available,
break line after sentence, nroff cleanup
2001-06-25 11:18:27 +08:00
RA, \fInot\fP set) and `|' (truncated message, TC, set).
If the
Initial revision
1999-10-08 07:47:09 +08:00
`question' section doesn't contain exactly one entry, `[\fIn\fPq]'
is printed.
.LP
Note that name server requests and responses tend to be large and the
default \fIsnaplen\fP of 68 bytes may not capture enough of the packet
break line after sentence, nroff cleanup
2001-06-25 11:18:27 +08:00
to print.
Use the \fB\-s\fP flag to increase the snaplen if you
need to seriously investigate name server traffic.
`\fB\-s 128\fP'
Initial revision
1999-10-08 07:47:09 +08:00
has worked well for me.
patches from Andrew Tridgell <tridge@linuxcare.com> to add decoding of SMB packets
1999-11-21 23:57:50 +08:00
.HD
SMB/CIFS decoding
.LP
Add documentation for Token Ring. Change some font choices to match the conventions used historically in this man page (use boldface for literal strings, italics for variables, and italics for "tcpdump" when it refers to the name of the program).
2000-07-25 14:09:32 +08:00
\fItcpdump\fP now includes fairly extensive SMB/CIFS/NBT decoding for data
break line after sentence, nroff cleanup
2001-06-25 11:18:27 +08:00
on UDP/137, UDP/138 and TCP/139.
Some primitive decoding of IPX and
NetBEUI SMB data is also done.
patches from Andrew Tridgell <tridge@linuxcare.com> to add decoding of SMB packets
1999-11-21 23:57:50 +08:00
By default a fairly minimal decode is done, with a much more detailed
break line after sentence, nroff cleanup
2001-06-25 11:18:27 +08:00
decode done if -v is used.
Be warned that with -v a single SMB packet
patches from Andrew Tridgell <tridge@linuxcare.com> to add decoding of SMB packets
1999-11-21 23:57:50 +08:00
may take up a page or more, so only use -v if you really want all the
gory details.
If you are decoding SMB sessions containing unicode strings then you
break line after sentence, nroff cleanup
2001-06-25 11:18:27 +08:00
may wish to set the environment variable USE_UNICODE to 1.
A patch to
patches from Andrew Tridgell <tridge@linuxcare.com> to add decoding of SMB packets
1999-11-21 23:57:50 +08:00
auto-detect unicode srings would be welcome.
For information on SMB packet formats and what all te fields mean see
www.cifs.org or the pub/samba/specs/ directory on your favourite
break line after sentence, nroff cleanup
2001-06-25 11:18:27 +08:00
samba.org mirror site.
The SMB patches were written by Andrew Tridgell
patches from Andrew Tridgell <tridge@linuxcare.com> to add decoding of SMB packets
1999-11-21 23:57:50 +08:00
(tridge@samba.org).
Initial revision
1999-10-08 07:47:09 +08:00
.HD
NFS Requests and Replies
.LP
Sun NFS (Network File System) requests and replies are printed as:
.RS
.nf
.sp .5
\fIsrc.xid > dst.nfs: len op args\fP
\fIsrc.nfs > dst.xid: reply stat len op results\fP
.sp .5
\f(CW
sushi.6709 > wrl.nfs: 112 readlink fh 21,24/10.73165
wrl.nfs > sushi.6709: reply ok 40 readlink "../var"
sushi.201b > wrl.nfs:
144 lookup fh 9,74/4096.6878 "xcolors"
wrl.nfs > sushi.201b:
reply ok 128 lookup fh 9,74/4134.3150
Make the introductory section of the README file use the same style as the introductory README section of the libpcap README file, giving information about anonymous CVS and other additional information. Update to note that non-patch mail should be sent to "tcpdump-workers@tcpdump.org", and that patches should be sent to "patches@tcpdump.org". Merge in changes from the tcpdump 3.5 branch: "\f(CW" doesn't work on all systems - which appears to cause a subsequent "\fP" to revert to the font from which *roff last switched, which is often an italic or boldface font. Use "\fR" instead of "\fP" to undo a "\f(CW". and other changes not in the main line.
2000-07-13 14:36:57 +08:00
\fR
Initial revision
1999-10-08 07:47:09 +08:00
.sp .5
.fi
.RE
In the first line, host \fIsushi\fP sends a transaction with id \fI6709\fP
to \fIwrl\fP (note that the number following the src host is a
break line after sentence, nroff cleanup
2001-06-25 11:18:27 +08:00
transaction id, \fInot\fP the source port).
The request was 112 bytes,
excluding the UDP and IP headers.
The operation was a \fIreadlink\fP
Initial revision
1999-10-08 07:47:09 +08:00
(read symbolic link) on file handle (\fIfh\fP) 21,24/10.731657119.
(If one is lucky, as in this case, the file handle can be interpreted
as a major,minor device number pair, followed by the inode number and
generation number.)
\fIWrl\fP replies `ok' with the contents of the link.
.LP
In the third line, \fIsushi\fP asks \fIwrl\fP to lookup the name
break line after sentence, nroff cleanup
2001-06-25 11:18:27 +08:00
`\fIxcolors\fP' in directory file 9,74/4096.6878.
Note that the data printed
depends on the operation type.
The format is intended to be self
Initial revision
1999-10-08 07:47:09 +08:00
explanatory if read in conjunction with
an NFS protocol spec.
.LP
If the \-v (verbose) flag is given, additional information is printed.
For example:
.RS
.nf
.sp .5
\f(CW
sushi.1372a > wrl.nfs:
148 read fh 21,11/12.195 8192 bytes @ 24576
wrl.nfs > sushi.1372a:
reply ok 1472 read REG 100664 ids 417/0 sz 29388
\fP
.sp .5
.fi
.RE
print IP length. From Kevin Steves <stevesk@sweden.hp.com>
2000-07-29 14:06:27 +08:00
(\-v also prints the IP header TTL, ID, length, and fragmentation fields,
Initial revision
1999-10-08 07:47:09 +08:00
which have been omitted from this example.) In the first line,
\fIsushi\fP asks \fIwrl\fP to read 8192 bytes from file 21,11/12.195,
break line after sentence, nroff cleanup
2001-06-25 11:18:27 +08:00
at byte offset 24576.
\fIWrl\fP replies `ok'; the packet shown on the
Initial revision
1999-10-08 07:47:09 +08:00
second line is the first fragment of the reply, and hence is only 1472
bytes long (the other bytes will follow in subsequent fragments, but
these fragments do not have NFS or even UDP headers and so might not be
break line after sentence, nroff cleanup
2001-06-25 11:18:27 +08:00
printed, depending on the filter expression used).
Because the \-v flag
Initial revision
1999-10-08 07:47:09 +08:00
is given, some of the file attributes (which are returned in addition
to the file data) are printed: the file type (``REG'', for regular file),
the file mode (in octal), the uid and gid, and the file size.
.LP
If the \-v flag is given more than once, even more details are printed.
.LP
Note that NFS requests are very large and much of the detail won't be printed
break line after sentence, nroff cleanup
2001-06-25 11:18:27 +08:00
unless \fIsnaplen\fP is increased.
Try using `\fB\-s 192\fP' to watch
Initial revision
1999-10-08 07:47:09 +08:00
NFS traffic.
.LP
break line after sentence, nroff cleanup
2001-06-25 11:18:27 +08:00
NFS reply packets do not explicitly identify the RPC operation.
Instead,
Initial revision
1999-10-08 07:47:09 +08:00
\fItcpdump\fP keeps track of ``recent'' requests, and matches them to the
break line after sentence, nroff cleanup
2001-06-25 11:18:27 +08:00
replies using the transaction ID.
If a reply does not closely follow the
Initial revision
1999-10-08 07:47:09 +08:00
corresponding request, it might not be parsable.
Move AFS info into man page Submitted by: Ken Hornstein <kenh@cmf.nrl.navy.mil>
2000-01-28 07:53:49 +08:00
.HD
Make the introductory section of the README file use the same style as the introductory README section of the libpcap README file, giving information about anonymous CVS and other additional information. Update to note that non-patch mail should be sent to "tcpdump-workers@tcpdump.org", and that patches should be sent to "patches@tcpdump.org". Merge in changes from the tcpdump 3.5 branch: "\f(CW" doesn't work on all systems - which appears to cause a subsequent "\fP" to revert to the font from which *roff last switched, which is often an italic or boldface font. Use "\fR" instead of "\fP" to undo a "\f(CW". and other changes not in the main line.
2000-07-13 14:36:57 +08:00
AFS Requests and Replies
Move AFS info into man page Submitted by: Ken Hornstein <kenh@cmf.nrl.navy.mil>
2000-01-28 07:53:49 +08:00
.LP
Transarc AFS (Andrew File System) requests and replies are printed
as:
.HD
.RS
.nf
.sp .5
\fIsrc.sport > dst.dport: rx packet-type\fP
\fIsrc.sport > dst.dport: rx packet-type service call call-name args\fP
\fIsrc.sport > dst.dport: rx packet-type service reply call-name args\fP
.sp .5
\f(CW
elvis.7001 > pike.afsfs:
rx data fs call rename old fid 536876964/1/1 ".newsrc.new"
new fid 536876964/1/1 ".newsrc"
pike.afsfs > elvis.7001: rx data fs reply rename
Make the introductory section of the README file use the same style as the introductory README section of the libpcap README file, giving information about anonymous CVS and other additional information. Update to note that non-patch mail should be sent to "tcpdump-workers@tcpdump.org", and that patches should be sent to "patches@tcpdump.org". Merge in changes from the tcpdump 3.5 branch: "\f(CW" doesn't work on all systems - which appears to cause a subsequent "\fP" to revert to the font from which *roff last switched, which is often an italic or boldface font. Use "\fR" instead of "\fP" to undo a "\f(CW". and other changes not in the main line.
2000-07-13 14:36:57 +08:00
\fR
Move AFS info into man page Submitted by: Ken Hornstein <kenh@cmf.nrl.navy.mil>
2000-01-28 07:53:49 +08:00
.sp .5
.fi
.RE
break line after sentence, nroff cleanup
2001-06-25 11:18:27 +08:00
In the first line, host elvis sends a RX packet to pike.
This was
Move AFS info into man page Submitted by: Ken Hornstein <kenh@cmf.nrl.navy.mil>
2000-01-28 07:53:49 +08:00
a RX data packet to the fs (fileserver) service, and is the start of
break line after sentence, nroff cleanup
2001-06-25 11:18:27 +08:00
an RPC call.
The RPC call was a rename, with the old directory file id
Move AFS info into man page Submitted by: Ken Hornstein <kenh@cmf.nrl.navy.mil>
2000-01-28 07:53:49 +08:00
of 536876964/1/1 and an old filename of `.newsrc.new', and a new directory
break line after sentence, nroff cleanup
2001-06-25 11:18:27 +08:00
file id of 536876964/1/1 and a new filename of `.newsrc'.
The host pike
Move AFS info into man page Submitted by: Ken Hornstein <kenh@cmf.nrl.navy.mil>
2000-01-28 07:53:49 +08:00
responds with a RPC reply to the rename call (which was successful, because
it was a data packet and not an abort packet).
.LP
break line after sentence, nroff cleanup
2001-06-25 11:18:27 +08:00
In general, all AFS RPCs are decoded at least by RPC call name.
Most
Move AFS info into man page Submitted by: Ken Hornstein <kenh@cmf.nrl.navy.mil>
2000-01-28 07:53:49 +08:00
AFS RPCs have at least some of the arguments decoded (generally only
the `interesting' arguments, for some definition of interesting).
.LP
The format is intended to be self-describing, but it will probably
not be useful to people who are not familiar with the workings of
AFS and RX.
.LP
print the RX ack packets
2000-07-29 16:10:05 +08:00
If the -v (verbose) flag is given twice, acknowledgement packets and
additional header information is printed, such as the the RX call ID,
call number, sequence number, serial number, and the RX packet flags.
Make the handling of the -v flag a little more sensible, and document it.
2000-02-11 01:56:13 +08:00
.LP
Make the introductory section of the README file use the same style as the introductory README section of the libpcap README file, giving information about anonymous CVS and other additional information. Update to note that non-patch mail should be sent to "tcpdump-workers@tcpdump.org", and that patches should be sent to "patches@tcpdump.org". Merge in changes from the tcpdump 3.5 branch: "\f(CW" doesn't work on all systems - which appears to cause a subsequent "\fP" to revert to the font from which *roff last switched, which is often an italic or boldface font. Use "\fR" instead of "\fP" to undo a "\f(CW". and other changes not in the main line.
2000-07-13 14:36:57 +08:00
If the -v flag is given twice, additional information is printed,
Make the handling of the -v flag a little more sensible, and document it.
2000-02-11 01:56:13 +08:00
such as the the RX call ID, serial number, and the RX packet flags.
The MTU negotiation information is also printed from RX ack packets.
Move AFS info into man page Submitted by: Ken Hornstein <kenh@cmf.nrl.navy.mil>
2000-01-28 07:53:49 +08:00
.LP
Make the introductory section of the README file use the same style as the introductory README section of the libpcap README file, giving information about anonymous CVS and other additional information. Update to note that non-patch mail should be sent to "tcpdump-workers@tcpdump.org", and that patches should be sent to "patches@tcpdump.org". Merge in changes from the tcpdump 3.5 branch: "\f(CW" doesn't work on all systems - which appears to cause a subsequent "\fP" to revert to the font from which *roff last switched, which is often an italic or boldface font. Use "\fR" instead of "\fP" to undo a "\f(CW". and other changes not in the main line.
2000-07-13 14:36:57 +08:00
If the -v flag is given three times, the security index and service id
are printed.
Move AFS info into man page Submitted by: Ken Hornstein <kenh@cmf.nrl.navy.mil>
2000-01-28 07:53:49 +08:00
.LP
Error codes are printed for abort packets, with the exception of Ubik
beacon packets (because abort packets are used to signify a yes vote
for the Ubik protocol).
.LP
Note that AFS requests are very large and many of the arguments won't
break line after sentence, nroff cleanup
2001-06-25 11:18:27 +08:00
be printed unless \fIsnaplen\fP is increased.
Try using `\fB-s 256\fP'
Move AFS info into man page Submitted by: Ken Hornstein <kenh@cmf.nrl.navy.mil>
2000-01-28 07:53:49 +08:00
to watch AFS traffic.
.LP
break line after sentence, nroff cleanup
2001-06-25 11:18:27 +08:00
AFS reply packets do not explicitly identify the RPC operation.
Instead,
Move AFS info into man page Submitted by: Ken Hornstein <kenh@cmf.nrl.navy.mil>
2000-01-28 07:53:49 +08:00
\fItcpdump\fP keeps track of ``recent'' requests, and matches them to the
break line after sentence, nroff cleanup
2001-06-25 11:18:27 +08:00
replies using the call number and service ID.
If a reply does not closely
Move AFS info into man page Submitted by: Ken Hornstein <kenh@cmf.nrl.navy.mil>
2000-01-28 07:53:49 +08:00
follow the
corresponding request, it might not be parsable.
Initial revision
1999-10-08 07:47:09 +08:00
.HD
KIP Appletalk (DDP in UDP)
.LP
Appletalk DDP packets encapsulated in UDP datagrams are de-encapsulated
and dumped as DDP packets (i.e., all the UDP header information is
break line after sentence, nroff cleanup
2001-06-25 11:18:27 +08:00
discarded).
The file
Initial revision
1999-10-08 07:47:09 +08:00
.I /etc/atalk.names
is used to translate appletalk net and node numbers to names.
Lines in this file have the form
.RS
.nf
.sp .5
\fInumber name\fP
\f(CW1.254 ether
16.1 icsd-net
Make the introductory section of the README file use the same style as the introductory README section of the libpcap README file, giving information about anonymous CVS and other additional information. Update to note that non-patch mail should be sent to "tcpdump-workers@tcpdump.org", and that patches should be sent to "patches@tcpdump.org". Merge in changes from the tcpdump 3.5 branch: "\f(CW" doesn't work on all systems - which appears to cause a subsequent "\fP" to revert to the font from which *roff last switched, which is often an italic or boldface font. Use "\fR" instead of "\fP" to undo a "\f(CW". and other changes not in the main line.
2000-07-13 14:36:57 +08:00
1.254.110 ace\fR
Initial revision
1999-10-08 07:47:09 +08:00
.sp .5
.fi
.RE
break line after sentence, nroff cleanup
2001-06-25 11:18:27 +08:00
The first two lines give the names of appletalk networks.
The third
Initial revision
1999-10-08 07:47:09 +08:00
line gives the name of a particular host (a host is distinguished
from a net by the 3rd octet in the number \-
a net number \fImust\fP have two octets and a host number \fImust\fP
have three octets.) The number and name should be separated by
whitespace (blanks or tabs).
The
.I /etc/atalk.names
file may contain blank lines or comment lines (lines starting with
a `#').
.LP
Appletalk addresses are printed in the form
.RS
.nf
.sp .5
\fInet.host.port\fP
\f(CW144.1.209.2 > icsd-net.112.220
office.2 > icsd-net.112.220
Make the introductory section of the README file use the same style as the introductory README section of the libpcap README file, giving information about anonymous CVS and other additional information. Update to note that non-patch mail should be sent to "tcpdump-workers@tcpdump.org", and that patches should be sent to "patches@tcpdump.org". Merge in changes from the tcpdump 3.5 branch: "\f(CW" doesn't work on all systems - which appears to cause a subsequent "\fP" to revert to the font from which *roff last switched, which is often an italic or boldface font. Use "\fR" instead of "\fP" to undo a "\f(CW". and other changes not in the main line.
2000-07-13 14:36:57 +08:00
jssmag.149.235 > icsd-net.2\fR
Initial revision
1999-10-08 07:47:09 +08:00
.sp .5
.fi
.RE
(If the
.I /etc/atalk.names
doesn't exist or doesn't contain an entry for some appletalk
host/net number, addresses are printed in numeric form.)
In the first example, NBP (DDP port 2) on net 144.1 node 209
is sending to whatever is listening on port 220 of net icsd node 112.
The second line is the same except the full name of the source node
break line after sentence, nroff cleanup
2001-06-25 11:18:27 +08:00
is known (`office').
The third line is a send from port 235 on
Initial revision
1999-10-08 07:47:09 +08:00
net jssmag node 149 to broadcast on the icsd-net NBP port (note that
the broadcast address (255) is indicated by a net name with no host
number \- for this reason it's a good idea to keep node names and
net names distinct in /etc/atalk.names).
.LP
NBP (name binding protocol) and ATP (Appletalk transaction protocol)
break line after sentence, nroff cleanup
2001-06-25 11:18:27 +08:00
packets have their contents interpreted.
Other protocols just dump
Initial revision
1999-10-08 07:47:09 +08:00
the protocol name (or number if no name is registered for the
protocol) and packet size.
\fBNBP packets\fP are formatted like the following examples:
.RS
.nf
.sp .5
\s-2\f(CWicsd-net.112.220 > jssmag.2: nbp-lkup 190: "=:LaserWriter@*"
jssmag.209.2 > icsd-net.112.220: nbp-reply 190: "RM1140:LaserWriter@*" 250
Make the introductory section of the README file use the same style as the introductory README section of the libpcap README file, giving information about anonymous CVS and other additional information. Update to note that non-patch mail should be sent to "tcpdump-workers@tcpdump.org", and that patches should be sent to "patches@tcpdump.org". Merge in changes from the tcpdump 3.5 branch: "\f(CW" doesn't work on all systems - which appears to cause a subsequent "\fP" to revert to the font from which *roff last switched, which is often an italic or boldface font. Use "\fR" instead of "\fP" to undo a "\f(CW". and other changes not in the main line.
2000-07-13 14:36:57 +08:00
techpit.2 > icsd-net.112.220: nbp-reply 190: "techpit:LaserWriter@*" 186\fR\s+2
Initial revision
1999-10-08 07:47:09 +08:00
.sp .5
.fi
.RE
The first line is a name lookup request for laserwriters sent by net icsd host
break line after sentence, nroff cleanup
2001-06-25 11:18:27 +08:00
112 and broadcast on net jssmag.
The nbp id for the lookup is 190.
Initial revision
1999-10-08 07:47:09 +08:00
The second line shows a reply for this request (note that it has the
same id) from host jssmag.209 saying that it has a laserwriter
break line after sentence, nroff cleanup
2001-06-25 11:18:27 +08:00
resource named "RM1140" registered on port 250.
The third line is
Initial revision
1999-10-08 07:47:09 +08:00
another reply to the same request saying host techpit has laserwriter
"techpit" registered on port 186.
\fBATP packet\fP formatting is demonstrated by the following example:
.RS
.nf
.sp .5
\s-2\f(CWjssmag.209.165 > helios.132: atp-req 12266<0-7> 0xae030001
helios.132 > jssmag.209.165: atp-resp 12266:0 (512) 0xae040000
helios.132 > jssmag.209.165: atp-resp 12266:1 (512) 0xae040000
helios.132 > jssmag.209.165: atp-resp 12266:2 (512) 0xae040000
helios.132 > jssmag.209.165: atp-resp 12266:3 (512) 0xae040000
helios.132 > jssmag.209.165: atp-resp 12266:4 (512) 0xae040000
helios.132 > jssmag.209.165: atp-resp 12266:5 (512) 0xae040000
helios.132 > jssmag.209.165: atp-resp 12266:6 (512) 0xae040000
helios.132 > jssmag.209.165: atp-resp*12266:7 (512) 0xae040000
jssmag.209.165 > helios.132: atp-req 12266<3,5> 0xae030001
helios.132 > jssmag.209.165: atp-resp 12266:3 (512) 0xae040000
helios.132 > jssmag.209.165: atp-resp 12266:5 (512) 0xae040000
jssmag.209.165 > helios.132: atp-rel 12266<0-7> 0xae030001
Make the introductory section of the README file use the same style as the introductory README section of the libpcap README file, giving information about anonymous CVS and other additional information. Update to note that non-patch mail should be sent to "tcpdump-workers@tcpdump.org", and that patches should be sent to "patches@tcpdump.org". Merge in changes from the tcpdump 3.5 branch: "\f(CW" doesn't work on all systems - which appears to cause a subsequent "\fP" to revert to the font from which *roff last switched, which is often an italic or boldface font. Use "\fR" instead of "\fP" to undo a "\f(CW". and other changes not in the main line.
2000-07-13 14:36:57 +08:00
jssmag.209.133 > helios.132: atp-req* 12267<0-7> 0xae030002\fR\s+2
Initial revision
1999-10-08 07:47:09 +08:00
.sp .5
.fi
.RE
Jssmag.209 initiates transaction id 12266 with host helios by requesting
break line after sentence, nroff cleanup
2001-06-25 11:18:27 +08:00
up to 8 packets (the `<0-7>').
The hex number at the end of the line
Initial revision
1999-10-08 07:47:09 +08:00
is the value of the `userdata' field in the request.
.LP
break line after sentence, nroff cleanup
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Helios responds with 8 512-byte packets.
The `:digit' following the
Initial revision
1999-10-08 07:47:09 +08:00
transaction id gives the packet sequence number in the transaction
and the number in parens is the amount of data in the packet,
break line after sentence, nroff cleanup
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excluding the atp header.
The `*' on packet 7 indicates that the
Initial revision
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EOM bit was set.
.LP
break line after sentence, nroff cleanup
2001-06-25 11:18:27 +08:00
Jssmag.209 then requests that packets 3 & 5 be retransmitted.
Helios
resends them then jssmag.209 releases the transaction.
Finally,
jssmag.209 initiates the next request.
The `*' on the request
Initial revision
1999-10-08 07:47:09 +08:00
indicates that XO (`exactly once') was \fInot\fP set.
.HD
IP Fragmentation
.LP
Fragmented Internet datagrams are printed as
.RS
.nf
.sp .5
\fB(frag \fIid\fB:\fIsize\fB@\fIoffset\fB+)\fR
\fB(frag \fIid\fB:\fIsize\fB@\fIoffset\fB)\fR
.sp .5
.fi
.RE
break line after sentence, nroff cleanup
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(The first form indicates there are more fragments.
The second
Initial revision
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indicates this is the last fragment.)
.LP
break line after sentence, nroff cleanup
2001-06-25 11:18:27 +08:00
\fIId\fP is the fragment id.
\fISize\fP is the fragment
size (in bytes) excluding the IP header.
\fIOffset\fP is this
Initial revision
1999-10-08 07:47:09 +08:00
fragment's offset (in bytes) in the original datagram.
.LP
break line after sentence, nroff cleanup
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The fragment information is output for each fragment.
The first
Initial revision
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fragment contains the higher level protocol header and the frag
break line after sentence, nroff cleanup
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info is printed after the protocol info.
Fragments
Initial revision
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after the first contain no higher level protocol header and the
frag info is printed after the source and destination addresses.
For example, here is part of an ftp from arizona.edu to lbl-rtsg.arpa
over a CSNET connection that doesn't appear to handle 576 byte datagrams:
.RS
.nf
.sp .5
\s-2\f(CWarizona.ftp-data > rtsg.1170: . 1024:1332(308) ack 1 win 4096 (frag 595a:328@0+)
arizona > rtsg: (frag 595a:204@328)
rtsg.1170 > arizona.ftp-data: . ack 1536 win 2560\fP\s+2
.sp .5
.fi
.RE
There are a couple of things to note here: First, addresses in the
break line after sentence, nroff cleanup
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2nd line don't include port numbers.
This is because the TCP
Initial revision
1999-10-08 07:47:09 +08:00
protocol information is all in the first fragment and we have no idea
what the port or sequence numbers are when we print the later fragments.
Second, the tcp sequence information in the first line is printed as if there
were 308 bytes of user data when, in fact, there are 512 bytes (308 in
break line after sentence, nroff cleanup
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the first frag and 204 in the second).
If you are looking for holes
Initial revision
1999-10-08 07:47:09 +08:00
in the sequence space or trying to match up acks
with packets, this can fool you.
.LP
A packet with the IP \fIdon't fragment\fP flag is marked with a
trailing \fB(DF)\fP.
.HD
Timestamps
.LP
break line after sentence, nroff cleanup
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By default, all output lines are preceded by a timestamp.
The timestamp
Initial revision
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is the current clock time in the form
.RS
.nf
\fIhh:mm:ss.frac\fP
.fi
.RE
and is as accurate as the kernel's clock.
break line after sentence, nroff cleanup
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The timestamp reflects the time the kernel first saw the packet.
No attempt
Initial revision
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is made to account for the time lag between when the
ethernet interface removed the packet from the wire and when the kernel
serviced the `new packet' interrupt.
.SH "SEE ALSO"
traffic(1C), nit(4P), bpf(4), pcap(3)
.SH AUTHORS
update with new URLs and addresses (to tcpdump.org)
2000-06-12 14:50:50 +08:00
The original authors are:
.LP
Initial revision
1999-10-08 07:47:09 +08:00
Van Jacobson,
Craig Leres and
Steven McCanne, all of the
Lawrence Berkeley National Laboratory, University of California, Berkeley, CA.
.LP
update with new URLs and addresses (to tcpdump.org)
2000-06-12 14:50:50 +08:00
It is currently being maintained by tcpdump.org.
.LP
The current version is available via http:
.LP
.RS
.I http://www.tcpdump.org/
.RE
.LP
The original distribution is available via anonymous ftp:
Initial revision
1999-10-08 07:47:09 +08:00
.LP
.RS
.I ftp://ftp.ee.lbl.gov/tcpdump.tar.Z
.RE
Bring in KAME IPv6 tcpdump. replaces esp/ah/isakmp decoder. Hope I did not break anything. Portability on IPv4-only node needs checking, I'll do this very soon. (sorry for rather jumbo commit) XXx what is _FAVOR_BSD?
1999-10-30 13:11:06 +08:00
.LP
IPv6/IPsec support is added by WIDE/KAME project.
This program uses Eric Young's SSLeay library, under specific configuration.
Initial revision
1999-10-08 07:47:09 +08:00
.SH BUGS
Make the introductory section of the README file use the same style as the introductory README section of the libpcap README file, giving information about anonymous CVS and other additional information. Update to note that non-patch mail should be sent to "tcpdump-workers@tcpdump.org", and that patches should be sent to "patches@tcpdump.org". Merge in changes from the tcpdump 3.5 branch: "\f(CW" doesn't work on all systems - which appears to cause a subsequent "\fP" to revert to the font from which *roff last switched, which is often an italic or boldface font. Use "\fR" instead of "\fP" to undo a "\f(CW". and other changes not in the main line.
2000-07-13 14:36:57 +08:00
Please send problems, bugs, questions, desirable enhancements, etc. to:
update with new URLs and addresses (to tcpdump.org)
2000-06-12 14:50:50 +08:00
.LP
.RS
tcpdump-workers@tcpdump.org
.RE
Initial revision
1999-10-08 07:47:09 +08:00
.LP
Make the introductory section of the README file use the same style as the introductory README section of the libpcap README file, giving information about anonymous CVS and other additional information. Update to note that non-patch mail should be sent to "tcpdump-workers@tcpdump.org", and that patches should be sent to "patches@tcpdump.org". Merge in changes from the tcpdump 3.5 branch: "\f(CW" doesn't work on all systems - which appears to cause a subsequent "\fP" to revert to the font from which *roff last switched, which is often an italic or boldface font. Use "\fR" instead of "\fP" to undo a "\f(CW". and other changes not in the main line.
2000-07-13 14:36:57 +08:00
Please send source code contributions, etc. to:
.LP
.RS
patches@tcpdump.org
.RE
.LP
Initial revision
1999-10-08 07:47:09 +08:00
NIT doesn't let you watch your own outbound traffic, BPF will.
We recommend that you use the latter.
.LP
Clean up promiscuous mode, when using SOCK_PACKET, as best we can; remember which pcap_t's were opened (with SOCK_PACKET) in promiscuous mode on interfaces not already in promiscuous mode, turn promiscuous mode off when closing such a pcap_t, and arrange that, when the program exits, all pcap_t's of that sort not already closed have their interfaces taken out of promiscuous mode. (It's not sufficient to do this on exit - applications may close a pcap_t without exiting, e.g. Ethereal.) This won't always work right (if somebody else requests promiscuous mode after it's opened by libpcap, we'll turn promiscuous mode off when we close the pcap_t, and if the program doesn't exit cleanly, it won't clean up the interfaces), but neither of those problems are fixable - the only way to get things to work correctly is to use PF_PACKET sockets, which requires a 2.2 or later kernel. On a 2.0[.x] kernel, when doing a "recvfrom()" on a SOCK_PACKET socket to read a captured packet, don't pass a byte count value based on the snapshot length - "recvfrom()" won't return the actual packet length if you do that. (2.2 and later kernels will return the actual packet length if MSG_TRUNC is passed in.) Update the documentation to reflect improved Appletalk support.
2000-12-16 18:57:26 +08:00
On Linux systems with 2.0[.x] kernels:
.IP
packets on the loopback device will be seen twice;
.IP
packet filtering cannot be done in the kernel, so that all packets must
be copied from the kernel in order to be filtered in user mode;
.IP
all of a packet, not just the part that's within the snapshot length,
will be copied from the kernel (the 2.0[.x] packet capture mechanism, if
asked to copy only part of a packet to userland, will not report the
true length of the packet; this would cause most IP packets to get an
error from
Note that on Linux 2.0[.x] kernels, capturing on some PPP devices won't work correctly (because not all PPP devices have the same link-layer headers, but we don't try to figure out what type of link-layer header they'll have, and we can't work around that with PF_PACKET/SOCK_DGRAM cooked-mode capture if the kernel doesn't support PF_PACKET sockets, and 2.0[.x] kernels don't support PF_PACKET sockets).
2002-02-10 08:36:40 +08:00
.BR tcpdump );
.IP
capturing on some PPP devices won't work correctly.
Clean up promiscuous mode, when using SOCK_PACKET, as best we can; remember which pcap_t's were opened (with SOCK_PACKET) in promiscuous mode on interfaces not already in promiscuous mode, turn promiscuous mode off when closing such a pcap_t, and arrange that, when the program exits, all pcap_t's of that sort not already closed have their interfaces taken out of promiscuous mode. (It's not sufficient to do this on exit - applications may close a pcap_t without exiting, e.g. Ethereal.) This won't always work right (if somebody else requests promiscuous mode after it's opened by libpcap, we'll turn promiscuous mode off when we close the pcap_t, and if the program doesn't exit cleanly, it won't clean up the interfaces), but neither of those problems are fixable - the only way to get things to work correctly is to use PF_PACKET sockets, which requires a 2.2 or later kernel. On a 2.0[.x] kernel, when doing a "recvfrom()" on a SOCK_PACKET socket to read a captured packet, don't pass a byte count value based on the snapshot length - "recvfrom()" won't return the actual packet length if you do that. (2.2 and later kernels will return the actual packet length if MSG_TRUNC is passed in.) Update the documentation to reflect improved Appletalk support.
2000-12-16 18:57:26 +08:00
.LP
We recommend that you upgrade to a 2.2 or later kernel.
Document the deficiencies of tcpdump (of libpcap in general, actually) with the Linux 2.0[.x] kernel, and suggest that the user upgrade to a 2.2[.x] kernel.
2000-10-25 15:49:28 +08:00
.LP
Initial revision
1999-10-08 07:47:09 +08:00
Some attempt should be made to reassemble IP fragments or, at least
to compute the right length for the higher level protocol.
.LP
Add documentation for Token Ring. Change some font choices to match the conventions used historically in this man page (use boldface for literal strings, italics for variables, and italics for "tcpdump" when it refers to the name of the program).
2000-07-25 14:09:32 +08:00
Name server inverse queries are not dumped correctly: the (empty)
Initial revision
1999-10-08 07:47:09 +08:00
question section is printed rather than real query in the answer
break line after sentence, nroff cleanup
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section.
Some believe that inverse queries are themselves a bug and
Add documentation for Token Ring. Change some font choices to match the conventions used historically in this man page (use boldface for literal strings, italics for variables, and italics for "tcpdump" when it refers to the name of the program).
2000-07-25 14:09:32 +08:00
prefer to fix the program generating them rather than \fItcpdump\fP.
Initial revision
1999-10-08 07:47:09 +08:00
.LP
A packet trace that crosses a daylight savings time change will give
skewed time stamps (the time change is ignored).
.LP
Add documentation for Token Ring. Change some font choices to match the conventions used historically in this man page (use boldface for literal strings, italics for variables, and italics for "tcpdump" when it refers to the name of the program).
2000-07-25 14:09:32 +08:00
Filter expressions that manipulate FDDI or Token Ring headers assume
that all FDDI and Token Ring packets are SNAP-encapsulated Ethernet
break line after sentence, nroff cleanup
2001-06-25 11:18:27 +08:00
packets.
This is true for IP, ARP, and DECNET Phase IV, but is not true
for protocols such as ISO CLNS.
Therefore, the filter may inadvertently
Add documentation for Token Ring. Change some font choices to match the conventions used historically in this man page (use boldface for literal strings, italics for variables, and italics for "tcpdump" when it refers to the name of the program).
2000-07-25 14:09:32 +08:00
accept certain packets that do not properly match the filter expression.
.LP
Filter expressions on fields other than those that manipulate Token Ring
headers will not correctly handle source-routed Token Ring packets.
Bring in KAME IPv6 tcpdump. replaces esp/ah/isakmp decoder. Hope I did not break anything. Portability on IPv4-only node needs checking, I'll do this very soon. (sorry for rather jumbo commit) XXx what is _FAVOR_BSD?
1999-10-30 13:11:06 +08:00
.LP
.BR "ip6 proto"
should chase header chain, but at this moment it does not.
document -E. this option has very nasty effects and I'm still wondering if it is correct to include it in tcpdump.org distribution.
2000-01-15 15:54:15 +08:00
.BR "ip6 protochain"
is supplied for this behavior.
caveat: tcp[0] does not match IPv6 packets.
2000-01-30 00:39:27 +08:00
.LP
Arithmetic expression against transport layer headers, like \fBtcp[0]\fP,
does not work against IPv6 packets.
It only looks at IPv4 packets.
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