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NAME | SYNOPSIS | DESCRIPTION | OPTIONS | DIAGNOSTIC OPTIONS | SEE ALSO | NOTES | AUTHORS |
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TEXT2PCAP(1) TEXT2PCAP(1)
text2pcap - Generate a capture file from an ASCII hex dump of
packets
text2pcap [ -a ] [ -b 2|8|16|64 ] [ -D ] [ -e <ethertype> ] [ -E
<encapsulation type> ] [ -F <file format> ] [ -i <proto> ] [ -l
<typenum> ] [ -N <intf-name> ] [ -m <max-packet> ] [ -o
hex|oct|dec|none ] [ -q ] [ -r <regex> ] [ -s
<srcport>,<destport>,<tag> ] [ -S <srcport>,<destport>,<ppi> ] [
-t <timefmt> ] [ -T <srcport>,<destport> ] [ -u
<srcport>,<destport> ] [ -4 <srcip>,<destip> ] [ -6
<srcip>,<destip> ] [ --little-endian ] <infile>|- <outfile>|-
text2pcap -h|--help
text2pcap -v|--version
Text2pcap is a program that reads in an ASCII hex dump and writes
the data described into a capture file. text2pcap can read hex
dumps with multiple packets in them, and build a capture file of
multiple packets. Text2pcap is also capable of generating dummy
Ethernet, IP, and UDP, TCP or SCTP headers, in order to build
fully processable packet dumps from hex dumps of application-level
data only.
Text2pcap can write the file in several output formats. The -F
flag can be used to specify the format in which to write the
capture file, text2pcap -F provides a list of the available output
formats. By default, it writes the packets to outfile in the
pcapng file format. Text2pcap also supports compression formats,
which can be specified with the --compress options. If that option
is not given, the the desired compression method, if any, is
deduced from the extension of outfile; e.g. if it has the
extension '.gz', then the output file is compressed to a gzip
archive.
Text2pcap understands many different hex dump formats. The native
format that Wireshark displays in the Packet Bytes pane, copies to
the clipboard, prints, and saves, and that tshark produces with
the --hexdump option is that generated by od -Ax -tx1 -v or
hexdump -X -v. That is, each line must begin with an offset
describing the position in the packet, each byte is individually
displayed, with spaces separating the bytes from each other, and
repeated or all NUL ('\0') lines are not omitted. Hex digits can
be upper or lowercase. Text2pcap can handle other hex dump
formats, some of which can be automatically detected and some of
which require enabling options to properly recognize.
Offsets are followed by one or more spaces or tabs separating them
from the bytes. Offsets optionally can be followed by a single
colon after the digits. Offsets can be between 3 and 8 digits;
hexadecimal base (radix) is assumed by default, but they can be in
octal or decimal - see -o. If offsets are in hex, they can be
preceded by 0x or 0X. Each packet must begin with offset zero, and
an offset zero indicates the beginning of a new packet. Offset
values must be correct; an unexpected value causes the current
packet to be aborted and the next packet start awaited. There is
also a single packet mode with no offsets; see -o.
There is no limit on the width or number of bytes per line, but
lines with only hex bytes without a leading offset are ignored (in
other words, line breaks should not be inserted in long lines that
wrap.) Bytes must be in hex; unlike with offsets (and the
alternative regex mode mentioned later), other bases such as
octal, decimal, or binary are unsupported. Byte groups of two to
four bytes are also supported. By default byte groups are assumed
to be in network (big-endian) byte order; the --little-endian
option can be used to support little-endian byte order.
Packets may be preceded by a direction indicator ('I' or 'O')
and/or a timestamp if indicated by the command line (see -D and
-t). If both are present, the direction indicator precedes the
timestamp. The format of the timestamps is specified as a
mandatory parameter to -t. If no timestamp is parsed, in the case
of the first packet the current system time is used, while
subsequent packets are written with timestamps one microsecond
later than that of the previous packet.
Other text in the input data is ignored. Any text before the
offset is ignored, including email forwarding characters '>'. Any
text on a line after the bytes is ignored, e.g. an ASCII character
dump (but see -a to ensure that hex digits in the character dump
are ignored if there is no delimiter between the hex dump and the
ASCII character translation). Any line where the first
non-whitespace character is a '#' will be ignored as a comment.
Some hex dump utilities use a line containing a single '*' to
indicate omitted lines, either duplicating the previous line or
entirely consisting of NUL ('\0') bytes; this is not supported.
Any lines of text between the bytestring lines are considered
preamble; the beginning of the preamble is scanned for the
direction indicator and timestamp as mentioned above and otherwise
ignored.
Any line beginning with #TEXT2PCAP is a directive and options can
be inserted after this command to be processed by text2pcap.
Currently there are no directives implemented; in the future,
these may be used to give more fine grained control on the dump
and the way it should be processed e.g. timestamps, encapsulation
type etc.
In general, short of these restrictions, text2pcap is pretty
liberal about reading in hex dumps and has been tested with a
variety of mangled outputs (including being forwarded through
email multiple times, with limited line wrap etc.)
Here is a sample dump that text2pcap can recognize, with optional
directional indicator and timestamp:
I 2019-05-14T19:04:57Z
000000 00 0e b6 00 00 02 00 0e b6 00 00 01 08 00 45 00
000010 00 28 00 00 00 00 ff 01 37 d1 c0 00 02 01 c0 00
000020 02 02 08 00 a6 2f 00 01 00 01 48 65 6c 6c 6f 20
000030 57 6f 72 6c 64 21
000036
Text2pcap is also capable of scanning a text input file using a
custom Perl compatible regular expression that matches a single
packet. text2pcap searches the given file (which must end with
'\n') for non-overlapping non-empty strings matching the regex.
Named capturing subgroups, which must match exactly once per
packet, are used to identify fields to import. The following
fields are supported in regex mode, one mandatory and three
optional:
"data" Actual captured frame data to import
"time" Timestamp of packet
"dir" Direction of packet
"seqno" Arbitrary ID of packet
The 'data' field is the captured data, which must be in a selected
encoding: hexadecimal (the default), octal, binary, or base64 and
containing no characters in the data field outside the encoding
set besides whitespace. The 'time' field is parsed according to
the format in the -t parameter. The first character of the 'dir'
field is compared against a set of characters corresponding to
inbound and outbound that default to "iI<" for inbound and "oO>"
for outbound to assign a direction. The 'seqno' field is assumed
to be a positive integer base 10 used for an arbitrary ID. An
optional field’s information will only be written if the field is
present in the regex and if the capture file format supports it.
(E.g., the pcapng format supports all three fields, but the pcap
format only supports timestamps.)
Here is a sample dump that the regex mode can process with the
regex
'^(?<dir>[<>])\s(?<time>\d+:\d\d:\d\d.\d+)\s(?<data>[0-9a-fA-F]+)$'
along with timestamp format '%H:%M:%S.%f', directional indications
of '<' and '>', and hex encoding:
> 0:00:00.265620 a130368b000000080060
> 0:00:00.280836 a1216c8b00000000000089086b0b82020407
< 0:00:00.295459 a2010800000000000000000800000000
> 0:00:00.296982 a1303c8b00000008007088286b0bc1ffcbf0f9ff
> 0:00:00.305644 a121718b0000000000008ba86a0b8008
< 0:00:00.319061 a2010900000000000000001000600000
> 0:00:00.330937 a130428b00000008007589186b0bb9ffd9f0fdfa3eb4295e99f3aaffd2f005
> 0:00:00.356037 a121788b0000000000008a18
The regex is compiled with multiline support, and it is
recommended to use the anchors '^' and '$' for best results.
Text2pcap also allows the user to read in dumps of
application-level data and insert dummy L2, L3 and L4 headers
before each packet. This allows Wireshark or any other full-packet
decoder to handle these dumps. If the encapsulation type is
Ethernet, the user can elect to insert Ethernet headers, Ethernet
and IP, or Ethernet, IP and UDP/TCP/SCTP headers before each
packet. The fake headers can also be used with the Raw IP, Raw
IPv4, or Raw IPv6 encapsulations, with the Ethernet header
omitted. These encapsulation options can be used in both hex dump
mode and regex mode.
When <infile> or <outfile> are '-', standard input or standard
output, respectively, are used.
-a
Enables ASCII text dump identification. It allows one to
identify the start of the ASCII text dump and not include it
in the packet even if it looks like HEX. This parameter has no
effect in regex mode.
NOTE: Do not enable it if the input file does not contain the
ASCII text dump, or if the ASCII dump is separated from from
the hex dump by a non-blank delimiter such as |.
-b 2|8|16|64
Specify the base (radix) of the encoding of the packet data in
regex mode. The supported options are 2 (binary), 8 (octal),
16 (hexadecimal), and 64 (base64 encoding), with hex as the
default. This parameter has no effect in hex dump mode.
-D
Indicates that the text before each input packet may start
either with an I or O indicating that the packet is inbound or
outbound. If both this flag and the t flag are used, the
directional indicator is expected before the time code. This
parameter has no effect in regex mode, where the presence of
the <dir> capturing group determines whether direction
indicators are expected.
Direction indication is stored in the packet headers if the
output format supports it (e.g. pcapng), and is also used when
generating dummy headers to swap the source and destination
addresses and ports as appropriate.
-e <ethertype>
Include a dummy Ethernet header before each packet. Specify
the EtherType for the Ethernet header in hex. Use this option
if your dump has Layer 3 header and payload (e.g. IP header),
but no Layer 2 encapsulation. Example: -e 0x806 to specify an
ARP packet.
For IP packets, instead of generating a fake Ethernet header
you can also use -E rawip or -l 101 to indicate raw IP
encapsulation. Note that raw IP encapsulation does not work
for any non-IP Layer 3 packet (e.g. ARP), whereas generating a
dummy Ethernet header with -e works for any sort of L3 packet.
-E <encapsulation type>
Sets the packet encapsulation type of the output capture file.
text2pcap -E provides a list of the available types; note that
not all file formats support all encapsulation types. The
default type is ether (Ethernet).
NOTE: This sets the encapsulation type of the output file, but
does not translate the packet headers or add additional
headers. It is used to specify the encapsulation that matches
the input data.
-F <file format>
Sets the file format of the output capture file. Text2pcap can
write the file in several formats; text2pcap -F provides a
list of the available output formats. The default is the
pcapng format.
-h|--help
Print the version number and options and exit.
-i <proto>
Include dummy IP headers before each packet. Specify the IP
protocol for the packet in decimal. Use this option if your
dump is the payload of an IP packet (i.e. has complete L4
information) but does not have an IP header with each packet.
Note that an appropriate Ethernet header is automatically
included with each packet as well if the link-layer type is
Ethernet. Example: -i 46 to specify an RSVP packet (IP
protocol 46). See
https://www.iana.org/assignments/protocol-numbers/protocol-numbers.xhtml
for the complete list of assigned internet protocol numbers.
-l <typenum>
Sets the packet encapsulation type of the output capture file,
using pcap link-layer header type numbers. Default is Ethernet
(1). See https://www.tcpdump.org/linktypes.html for the
complete list of possible encapsulations. Example: -l 7 for
ARCNet packets encapsulated BSD-style.
-m <max-packet>
Set the maximum packet length, default is 262144. Useful for
testing various packet boundaries when only an application
level datastream is available. Example:
od -Ax -tx1 -v stream | text2pcap -m1460 -T1234,1234 -
stream.pcap
will convert from plain datastream format to a sequence of
Ethernet TCP packets.
-N <intf-name>
Specify a name for the interface included when writing a
pcapng format file.
-o hex|oct|dec|none
Specify the radix for the offsets (hex, octal, decimal, or
none). Defaults to hex. This corresponds to the -A option for
od. This parameter has no effect in regex mode.
NOTE: With -o none, only one packet will be created, ignoring
any direction indicators or timestamps after the first byte
along with any offsets.
-P <dissector>
Include an EXPORTED_PDU header before each packet. Specify, as
a string, the dissector to be called for the packet
(DISSECTOR_NAME tag). Use this option if your dump is the
payload for a single upper layer protocol (so specifying a
link layer type would not work) and you wish to create a
capture file without a full dummy protocol stack.
Automatically sets the link layer type to Wireshark Upper PDU
export. Without this option, if the Upper PDU export link
layer type (252) is selected the dissector defaults to "data".
-q
Don’t display the summary of the options selected at the
beginning, or the count of packets processed at the end.
-r <regex>
Process the file in regex mode using regex as described above.
NOTE: The regex mode uses memory-mapped I/O and does not work
on streams that do not support seeking, like terminals and
pipes.
-s <srcport>,<destport>,<tag>
Include dummy SCTP headers before each packet. Specify, in
decimal, the source and destination SCTP ports, and
verification tag, for the packet. Use this option if your dump
is the SCTP payload of a packet but does not include any SCTP,
IP or Ethernet headers. Note that appropriate Ethernet and IP
headers are automatically also included with each packet. A
CRC32C checksum will be put into the SCTP header.
-S <srcport>,<destport>,<ppi>
Include dummy SCTP headers before each packet. Specify, in
decimal, the source and destination SCTP ports, and a
verification tag of 0, for the packet, and prepend a dummy
SCTP DATA chunk header with a payload protocol identifier if
ppi. Use this option if your dump is the SCTP payload of a
packet but does not include any SCTP, IP or Ethernet headers.
Note that appropriate Ethernet and IP headers are
automatically included with each packet. A CRC32C checksum
will be put into the SCTP header.
-t <timefmt>
Treats the text before the packet as a date/time code; timefmt
is a format string supported by strftime(3), supplemented with
the field descriptor '%f' for fractional seconds up to
nanoseconds. Example: The time "10:15:14.5476" has the format
code "%H:%M:%S.%f" The special format string ISO indicates
that the string should be parsed according to the ISO-8601
specification. This parameter is used in regex mode if and
only if the <time> capturing group is present.
NOTE: Date/time fields from the current date/time are used as
the default for unspecified fields.
-T <srcport>,<destport>
Include dummy TCP headers before each packet. Specify the
source and destination TCP ports for the packet in decimal.
Use this option if your dump is the TCP payload of a packet
but does not include any TCP, IP or Ethernet headers. Note
that appropriate Ethernet and IP headers are automatically
also included with each packet. Sequence numbers will start at
0.
-u <srcport>,<destport>
Include dummy UDP headers before each packet. Specify the
source and destination UDP ports for the packet in decimal.
Use this option if your dump is the UDP payload of a packet
but does not include any UDP, IP or Ethernet headers. Note
that appropriate Ethernet and IP headers are automatically
also included with each packet. Example: -u1000,69 to make the
packets look like TFTP/UDP packets.
-v|--version
Print the full version information and exit.
-4 <srcip>,<destip>
Prepend dummy IP header with specified IPv4 source and
destination addresses. This option should be accompanied by
one of the following options: -i, -s, -S, -T, -u Use this
option to apply "custom" IP addresses. Example: -4
10.0.0.1,10.0.0.2 to use 10.0.0.1 and 10.0.0.2 for all IP
packets.
-6 <srcip>,<destip>
Prepend dummy IP header with specified IPv6 source and
destination addresses. This option should be accompanied by
one of the following options: -i, -s, -S, -T, -u Use this
option to apply "custom" IP addresses. Example: -6
2001:db8::b3ff:fe1e:8329,2001:0db8:85a3::8a2e:0370:7334 to use
2001:db8::b3ff:fe1e:8329 and 2001:0db8:85a3::8a2e:0370:7334
for all IP packets.
--compress <type>
Compress the output file using the type compression format.
--compress with no argument provides a list of the compression
formats supported for writing. The type given takes precedence
over the extension of outfile.
--little-endian
Treat multiple byte groups as in little-endian byte order,
instead of the default, network (big-endian) byte order.
NOTE: This only applies to byte groups. If -a is used, the
ASCII dump is still assumed to have the normal ordering.
--log-level <level>
Set the active log level. Supported levels in lowest to
highest order are "noisy", "debug", "info", "message",
"warning", "critical", and "error". Messages at each level and
higher will be printed, for example "warning" prints
"warning", "critical", and "error" messages and "noisy" prints
all messages. Levels are case insensitive.
--log-fatal <level>
Abort the program if any messages are logged at the specified
level or higher. For example, "warning" aborts on any
"warning", "critical", or "error" messages.
--log-domains <list>
Only print messages for the specified log domains, e.g.
"GUI,Epan,sshdump". List of domains must be comma-separated.
Can be negated with "!" as the first character (inverts the
match).
--log-debug <list>
Force the specified domains to log at the "debug" level. List
of domains must be comma-separated. Can be negated with "!" as
the first character (inverts the match).
--log-noisy <list>
Force the specified domains to log at the "noisy" level. List
of domains must be comma-separated. Can be negated with "!" as
the first character (inverts the match).
--log-fatal-domains <list>
Abort the program if any messages are logged for the specified
log domains. List of domains must be comma-separated.
--log-file <path>
Write log messages and stderr output to the specified file.
od(1), hexdump(1), xxd(1), pcap(3), wireshark(1), tshark(1),
dumpcap(1), mergecap(1), editcap(1), strftime(3), pcap-filter(7)
or tcpdump(8)
This is the manual page for Text2pcap 4.5.0. Text2pcap is part of
the Wireshark distribution. The latest version of Wireshark can be
found at https://www.wireshark.org.
Original Author
Ashok Narayanan <ashokn[AT]cisco.com>.SH COLOPHON This page is
part of the wireshark (Interactively dump and analyze network
traffic) project. Information about the project can be found at
⟨https://www.wireshark.org/⟩. If you have a bug report for this
manual page, see
⟨https://gitlab.com/wireshark/wireshark/-/issues⟩. This page was
obtained from the project's upstream Git repository
⟨https://gitlab.com/wireshark/wireshark.git⟩ on 2025-08-11. (At
that time, the date of the most recent commit that was found in
the repository was 2025-08-11.) If you discover any rendering
problems in this HTML version of the page, or you believe there is
a better or more up-to-date source for the page, or you have
corrections or improvements to the information in this COLOPHON
(which is not part of the original manual page), send a mail to
[email protected]
2025-08-09 TEXT2PCAP(1)
Pages that refer to this page: editcap(1), mergecap(1), rawshark(1), reordercap(1), tshark(1), wireshark(1)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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