TEXT2PCAP(1) The Ethereal Network Analyzer TEXT2PCAP(1)NAMEtext2pcap - Generate a capture file from an ASCII hexdump
of packets
SYNOPSYStext2pcap [ -h ] [ -d ] [ -q ] [ -o hex|oct ]
[ -l typenum ] [ -e l3pid ] [ -i proto ] [ -m max-packet ]
[ -u srcport,destport ] [ -T srcport,destport ]
[ -s srcport,destport,tag ] [ -S srcport,destport,ppi ]
[ -t timefmt ] infile outfile
DESCRIPTION
Text2pcap is a program that reads in an ASCII hex dump and
writes the data described into a libpcap-style capture
file. text2pcap can read hexdumps with multiple packets in
them, and build a capture file of multiple packets.
text2pcap is also capable of generating dummy Ethernet, IP
and UDP or TCP headers, in order to build fully
processable packet dumps from hexdumps of application-
level data only.
Text2pcap understands a hexdump of the form generated by
od -t x1. In other words, each byte is individually
displayed and surrounded with a space. Each line begins
with an offset describing the position in the file. The
offset is a hex number (can also be octal - see -o), of
more than two hex digits. Here is a sample dump that
text2pcap can recognize:
000000 00 e0 1e a7 05 6f 00 10 ........
000008 5a a0 b9 12 08 00 46 00 ........
000010 03 68 00 00 00 00 0a 2e ........
000018 ee 33 0f 19 08 7f 0f 19 ........
000020 03 80 94 04 00 00 10 01 ........
000028 16 a2 0a 00 03 50 00 0c ........
000030 01 01 0f 19 03 80 11 01 ........
There is no limit on the width or number of bytes per
line. Also the text dump at the end of the line is
ignored. Bytes/hex numbers can be uppercase or lowercase.
Any text before the offset is ignored, including email
forwarding characters '>'. Any lines of text between the
bytestring lines is ignored. The offsets are used to track
the bytes, so offsets must be correct. Any line which has
only bytes without a leading offset is ignored. An offset
is recognized as being a hex number longer than two
characters. Any text after the bytes is ignored (e.g. the
character dump). Any hex numbers in this text are also
ignored. An offset of zero is indicative of starting a new
packet, so a single text file with a series of hexdumps
can be converted into a packet capture with multiple
packets. Multiple packets are read in with timestamps
differing by one second each. In general, short of these
restrictions, text2pcap is pretty liberal about reading in
hexdumps and has been tested with a variety of mangled
outputs (including being forwarded through email multiple
times, with limited line wrap etc.)
There are a couple of other special features to note. Any
line where the first non-whitespace character is '#' will
be ignored as a comment. 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.
Text2pcap also allows the user to read in dumps of
application-level data, by inserting dummy L2, L3 and L4
headers before each packet. The user can elect to insert
Ethernet headers, Ethernet and IP, or Ethernet, IP and
UDP/TCP headers before each packet. This allows Ethereal
or any other full-packet decoder to handle these dumps.
OPTIONS-h Displays a help message.
-d Displays debugging information during the process. Can
be used multiple times to generate more debugging
information.
-q Be completely quiet during the process.
-o hex|oct
Specify the radix for the offsets (hex or octal).
Defaults to hex. This corresponds to the -A option for
od.
-l Specify the link-layer type of this packet. Default is
Ethernet (1). See net/bpf.h for the complete list of
possible encapsulations. Note that this option should
be used if your dump is a complete hex dump of an
encapsulated packet and you wish to specify the exact
type of encapsulation. Example: -l 7 for ARCNet
packets.
-e l3pid
Include a dummy Ethernet header before each packet.
Specify the L3PID 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 -l 12 to indicate a raw IP
packet to Ethereal. Note that -l 12 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.
-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. Note that this automatically includes an
appropriate Ethernet header as well. Example: -i 46 to
specify an RSVP packet (IP protocol 46).
-m max-packet
Set the maximum packet length, default is 64000.
Useful for testing various packet boundaries when only
an application level datastream is available.
Example:
od -Ax -tx1 stream | text2pcap-m1460 -T1234,1234 -
stream.pcap
will convert from plain datastream format to a
sequence of Ethernet TCP packets.
-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 this automatically
includes appropriate Ethernet and IP headers with each
packet. Example: -u 1000,69 to make the packets look
like TFTP/UDP packets.
-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 this automatically
includes appropriate Ethernet and IP headers with each
packet. Sequence numbers will start a 0.
-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 this automatically includes appropriate
Ethernet and IP headers 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 this automatically includes appropriate Ethernet
and IP headers 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 of the sort supported by
strptime(3). Example: The time "10:15:14.5476" has
the format code "%H:%M:%S."
NOTE: The subsecond component delimiter must be
specified (.) but no pattern is required; the
remaining number is assumed to be fractions of a
second.
SEE ALSOtcpdump(8), pcap(3), ethereal(1), editcap(1), strptime(3).
NOTES
Text2pcap is part of the Ethereal distribution. The
latest version of Ethereal can be found at
http://www.ethereal.com.
AUTHORS
Ashok Narayanan <ashokn[AT]cisco.com>
26/Apr/2003 0.9.12 TEXT2PCAP(1)
