Provided by: tcpslice_1.5-1_amd64 
NAME
tcpslice - extract pieces of and/or merge together pcap files
SYNOPSIS
tcpslice [ -DdlhRrtv ] [ -w file ]
[ -s types [ -e seconds ] [ -f format ] ]
[ start-time [ end-time ] ] file ...
DESCRIPTION
Tcpslice is a program for extracting portions of packet-trace files generated using
tcpdump(1)'s -w flag. It can also be used to merge together several such files, as
discussed below.
The basic operation of tcpslice is to copy to stdout all packets from its input file(s)
whose timestamps fall within a given range. The starting and ending times of the range
may be specified on the command line. All ranges are inclusive. The starting time
defaults to the earliest time of the first packet in any of the input files; we call this
the first time. The ending time defaults to ten years after the starting time. Thus, the
command tcpslice trace-file simply copies trace-file to stdout (assuming the file does not
include more than ten years' worth of data).
There are a number of ways to specify times. The first is using Unix timestamps of the
form sssssssss.uuuuuu (this is the format specified by tcpdump's -tt flag). For example,
654321098.7654 specifies 38 seconds and 765,400 microseconds after 8:51PM PDT, Sept. 25,
1990.
All examples in this manual are given for PDT times, but when displaying times and
interpreting times symbolically as discussed below, tcpslice uses the local timezone,
regardless of the timezone in which the pcap file was generated. The daylight-savings
setting used is that which is appropriate for the local timezone at the date in question.
For example, times associated with summer months will usually include daylight-savings
effects, and those with winter months will not.
Times may also be specified relative to either the first time (when specifying a starting
time) or the starting time (when specifying an ending time) by preceding a numeric value
in seconds with a `+'. For example, a starting time of +200 indicates 200 seconds after
the first time, and the two arguments +200 +300 indicate from 200 seconds after the first
time through 500 seconds after the first time.
Times may also be specified in terms of years (y), months (m), days (d), hours (h),
minutes (m), seconds (s), and microseconds(u). For example, the Unix timestamp
654321098.7654 discussed above could also be expressed as 1990y9m25d20h51m38s765400u. 2
or 4 digit years may be used; 2 digits can specify years from 1970 to 2069.
When specifying times using this style, fields that are omitted default as follows. If
the omitted field is a unit greater than that of the first specified field, then its value
defaults to the corresponding value taken from either first time (if the starting time is
being specified) or the starting time (if the ending time is being specified). If the
omitted field is a unit less than that of the first specified field, then it defaults to
zero (1 for days). For example, suppose that the input file has a first time of the Unix
timestamp mentioned above, i.e., 38 seconds and 765,400 microseconds after 8:51PM PDT,
Sept. 25, 1990. To specify 9:36PM PDT (exactly) on the same date we could use 21h36m. To
specify a range from 9:36PM PDT through 1:54AM PDT the next day we could use 21h36m
26d1h54m.
Relative times can also be specified when using the ymdhmsu format. Omitted fields then
default to 0 if the unit of the field is greater than that of the first specified field,
and to the corresponding value taken from either the first time or the starting time if
the omitted field's unit is less than that of the first specified field. Given a first
time of the Unix timestamp mentioned above, 22h +1h10m specifies a range from 10:00PM PDT
on that date through 11:10PM PDT, and +1h +1h10m specifies a range from 38.7654 seconds
after 9:51PM PDT through 38.7654 seconds after 11:01PM PDT. The first hour of the file
could be extracted using +0 +1h.
Note that with the ymdhmsu format there is an ambiguity between using m for `month' or for
`minute'. The ambiguity is resolved as follows: if an m field is followed by a d field
then it is interpreted as specifying months; otherwise it specifies minutes.
If more than one input file is specified then tcpslice merges the packets from the various
input files into the single output file. Normally, this merge is done based on the value
of the time stamps in the packets in the individual files. (Tcpslice assumes that within
each input file, packets are in time stamp order.) If the -l option is used, the value
used for ordering is the time stamp of a given packet minus the time stamp of the first
packet in the input file in which the given packet occurs.
When merging files, by default tcpslice will discard any duplicate packet it finds in more
than one file. A duplicate is a packet that has an identical timestamp (either relative
or absolute) and identical packet contents (for as much as was captured) as another packet
previously seen in a different file. Note that it is possible for the network to generate
true replicates of packets, and for systems that can return the same timestamp for
multiple packets, these can be mistaken for duplicates and discarded. Accordingly,
tcpslice will not discard duplicates in the same trace file. In addition, you can use the
-D option to suppress any discarding of duplicates.
OPTIONS
If any of -R, -r or -t are specified then tcpslice reports the timestamps of the first and
last packets in each input file and exits. Only one of these three options may be
specified.
-D Do not discard duplicate packets seen when merging multiple trace files.
-d Dump the start and end times specified by the given range and exit. This option is
useful for checking that the given range actually specifies the times you think it
does. If one of -R, -r or -t has been specified then the times are dumped in the
corresponding format; otherwise, raw format (-R) is used.
-e Specify a number of seconds to wait after the last packet was seen before
considering a session to be expired (default: 0 = do not expire inactive sessions).
This is only effective when the -s option is used to track sessions.
-f Specify the name format of PCAP files to which each session will be extracted
(default: NULL = do not extract sessions to separate files). This is only effective
when the -s option is used to track sessions.
-h Print the tcpslice and libpcap version strings, print a usage message, and exit.
-l When merging more than one file, merge on the basis of relative time, rather than
absolute time. Normally, when merging files is done, packets are merged based on
absolute time stamps. With -l packets are merged based on the relative time
between the start of the file in which the packet is found and the time stamp of
the packet itself. The time stamp of packets in the output file is calculated as
the relative time for the packet within its file plus first time.
-R Dump the timestamps of the first and last packets in each input file as raw
timestamps (i.e., in the form sssssssss.uuuuuu).
-r Same as -R except the timestamps are dumped in human-readable format, similar to
that used by date(1).
-s Enable session tracking for the specified types which is a comma-separated list of
the following:
tcp track all TCP connections
sip track SIP-based VoIP calls, which may enable tracking of TCP connections but
only the ones that are related to SIP calls. This feature is only available
if tcpslice was linked against Aymeric Moizard's GNU oSIP library; if not,
install the latest version of libosip2 from
https://www.gnu.org/software/osip/ and recompile tcpslice.
h323 track H.323-based VoIP calls, which may enable tracking of TCP connections
but only the ones that are related to H.323 calls. This feature is only
available if tcpslice was linked against Objective Systems' Open H.323
library for C; if not, install the latest version of libooh323c from
https://sourceforge.net/projects/ooh323c/ and recompile tcpslice.
Session tracking altogether is only available if tcpslice was linked against a
recent version (>1.20) of Rafal Wojtczuk's Network Intrusion Detection System
library; if not, install the latest version of libnids from
http://libnids.sourceforge.net/ and recompile tcpslice.
-t Same as -R except the timestamps are dumped in tcpslice format, i.e., in the
ymdhmsu format discussed above.
-v Turn on verbose mode. Currently this only affects session tracking (-s) messages:
if specified at least once, sessions openings and closings are displayed regardless
of the time (by default the closings are only displayed past end-time); if
specified at least twice, subsessions (sessions initiated by other sessions)
openings and closings are also displayed.
-w Direct the output to file rather than stdout.
SEE ALSO
tcpdump(1)
AUTHORS
The original author was:
Vern Paxson, of Lawrence Berkeley Laboratory, University of California, Berkeley, CA.
It is currently being maintained by The Tcpdump Group.
The current version is available at:
https://github.com/the-tcpdump-group/tcpslice
The original distribution is available via anonymous ftp:
ftp://ftp.ee.lbl.gov/tcpslice-1.2a3.tar.gz
BUGS
Please send problems, bugs, questions, desirable enhancements, etc. to:
tcpdump-workers@lists.tcpdump.org
Please send source code contributions as git pull requests through the project page above.
An input filename that exactly matches the sssssssss.uuuuuu or the ymdhmsu format
discussed above can be confused with a start/end time (regardless if the date and the time
are valid in the latter case). Such filenames can be specified with a leading `./'; for
example, specify the file `1976y07m04d' as `./1976y07m04d' and `00000123' as `./00000123'.
Alternatively, renaming the files to `1976y07m04d.pcap' and `00000123.pcap' respectively
would resolve this ambiguity.
tcpslice cannot read its input from stdin, since it uses random-access to rummage through
its input files.
tcpslice refuses to write to its output if it is a terminal (as indicated by isatty(3)).
This is not a bug but a feature, to prevent it from spraying binary data to the user's
terminal. Note that this means you must either redirect stdout or specify an output file
via -w.
tcpslice will not work properly on pcap files spanning more than one year; with files
containing portions of packets whose original length was more than 65,535 bytes; nor with
files containing fewer than two packets. Such files result in the error message:
`couldn't find final packet in file'. These problems are due to the interpolation scheme
used by tcpslice to greatly speed up its processing when dealing with large trace files.
Note that tcpslice can efficiently extract slices from the middle of trace files of any
size, and can also work with truncated trace files (i.e., the final packet in the file is
only partially present, typically due to tcpdump being ungracefully killed).
Adding -l has broken some compatibility with older versions, since tcpslice now merges its
input files, rather than (approximately) concatenating them together as it did previously.
It would sometimes be convenient if you could specify a clock offset to use with the -l
option.
It would be nice if tcpslice supported more general editing of trace files.
30 July 2020 TCPSLICE(1)