1TEXT2PCAP(1) TEXT2PCAP(1)
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6 text2pcap - Generate a capture file from an ASCII hexdump of packets
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9 text2pcap [ -a ] [ -d ] [ -D ] [ -e <l3pid> ] [ -h ] [ -i <proto> ]
10 [ -l <typenum> ] [ -n ] [ -N <intf-name> ] [ -m <max-packet> ]
11 [ -o hex|oct|dec ] [ -q ] [ -s <srcport>,<destport>,<tag> ]
12 [ -S <srcport>,<destport>,<ppi> ] [ -t <timefmt> ]
13 [ -T <srcport>,<destport> ] [ -u <srcport>,<destport> ] [ -v ]
14 [ -4 <srcip>,<destip> ] [ -6 <srcip>,<destip> ] <infile>|- <outfile>|-
15
17 Text2pcap is a program that reads in an ASCII hex dump and writes the
18 data described into a pcap or pcapng capture file. text2pcap can read
19 hexdumps with multiple packets in them, and build a capture file of
20 multiple packets. text2pcap is also capable of generating dummy
21 Ethernet, IP and UDP, TCP, or SCTP headers, in order to build fully
22 processable packet dumps from hexdumps of application-level data only.
23 Text2pcap understands a hexdump of the form generated by od -Ax -tx1
25 -v. In other words, each byte is individually displayed, with spaces
26 separating the bytes from each other. Each line begins with an offset
27 describing the position in the packet, each new packet starts with an
28 offset of 0 and there is a space separating the offset from the
29 following bytes. The offset is a hex number (can also be octal or
30 decimal - see -o), of more than two hex digits.
31 Here is a sample dump that text2pcap can recognize:
33 000000 00 0e b6 00 00 02 00 0e b6 00 00 01 08 00 45 00
35 000010 00 28 00 00 00 00 ff 01 37 d1 c0 00 02 01 c0 00
36 000020 02 02 08 00 a6 2f 00 01 00 01 48 65 6c 6c 6f 20
37 000030 57 6f 72 6c 64 21
38 000036
39 Note the last byte must either be followed by the expected next offset
41 value as in the example above or a space or a line-end character(s).
42 There is no limit on the width or number of bytes per line. Also the
44 text dump at the end of the line is ignored. Bytes/hex numbers can be
45 uppercase or lowercase. Any text before the offset is ignored,
46 including email forwarding characters '>'. Any lines of text between
47 the bytestring lines is ignored. The offsets are used to track the
48 bytes, so offsets must be correct. Any line which has only bytes
49 without a leading offset is ignored. An offset is recognized as being a
50 hex number longer than two characters. Any text after the bytes is
51 ignored (e.g. the character dump). Any hex numbers in this text are
52 also ignored. An offset of zero is indicative of starting a new packet,
53 so a single text file with a series of hexdumps can be converted into a
54 packet capture with multiple packets. Packets may be preceded by a
55 timestamp. These are interpreted according to the format given on the
56 command line (see -t). If not, the first packet is timestamped with the
57 current time the conversion takes place. Multiple packets are written
58 with timestamps differing by one microsecond each. In general, short of
59 these restrictions, text2pcap is pretty liberal about reading in
60 hexdumps and has been tested with a variety of mangled outputs
61 (including being forwarded through email multiple times, with limited
62 line wrap etc.)
63 There are a couple of other special features to note. Any line where
65 the first non-whitespace character is '#' will be ignored as a comment.
66 Any line beginning with #TEXT2PCAP is a directive and options can be
67 inserted after this command to be processed by text2pcap. Currently
68 there are no directives implemented; in the future, these may be used
69 to give more fine grained control on the dump and the way it should be
70 processed e.g. timestamps, encapsulation type etc.
71 Text2pcap also allows the user to read in dumps of application-level
73 data, by inserting dummy L2, L3 and L4 headers before each packet. The
74 user can elect to insert Ethernet headers, Ethernet and IP, or
75 Ethernet, IP and UDP/TCP/SCTP headers before each packet. This allows
76 Wireshark or any other full-packet decoder to handle these dumps.
77
79 -a
80 Enables ASCII text dump identification. It allows one to identify
82 the start of the ASCII text dump and not include it in the packet
83 even if it looks like HEX.
84 NOTE: Do not enable it if the input file does not contain the ASCII
86 text dump.
87 -d
89 Displays debugging information during the process. Can be used
91 multiple times to generate more debugging information.
92 -D
94 The text before the packet starts either with an I or O indicating
96 that the packet is inbound or outbound. This is used when
97 generating dummy headers. The indication is only stored if the
98 output format is pcapng.
99 -e <l3pid>
101 Include a dummy Ethernet header before each packet. Specify the
103 L3PID for the Ethernet header in hex. Use this option if your dump
104 has Layer 3 header and payload (e.g. IP header), but no Layer 2
105 encapsulation. Example: -e 0x806 to specify an ARP packet.
106 For IP packets, instead of generating a fake Ethernet header you
108 can also use -l 101 to indicate a raw IP packet to Wireshark. Note
109 that -l 101 does not work for any non-IP Layer 3 packet (e.g. ARP),
110 whereas generating a dummy Ethernet header with -e works for any
111 sort of L3 packet.
112 -h
114 Displays a help message.
116 -i <proto>
118 Include dummy IP headers before each packet. Specify the IP
120 protocol for the packet in decimal. Use this option if your dump is
121 the payload of an IP packet (i.e. has complete L4 information) but
122 does not have an IP header with each packet. Note that an
123 appropriate Ethernet header is automatically included with each
124 packet as well. Example: -i 46 to specify an RSVP packet (IP
125 protocol 46). See
126 https://www.iana.org/assignments/protocol-numbers/protocol-numbers.xhtml
127 for the complete list of assigned internet protocol numbers.
128 -l
130 Specify the link-layer header type of this packet. Default is
132 Ethernet (1). See https://www.tcpdump.org/linktypes.html for the
133 complete list of possible encapsulations. Note that this option
134 should be used if your dump is a complete hex dump of an
135 encapsulated packet and you wish to specify the exact type of
136 encapsulation. Example: -l 7 for ARCNet packets encapsulated
137 BSD-style.
138 -m <max-packet>
140 Set the maximum packet length, default is 262144. Useful for
142 testing various packet boundaries when only an application level
143 datastream is available. Example:
144 od -Ax -tx1 -v stream | text2pcap -m1460 -T1234,1234 - stream.pcap
146 will convert from plain datastream format to a sequence of Ethernet
148 TCP packets.
149 -n
151 Write the file in pcapng format rather than pcap format.
153 -N <intf-name>
155 Specify a name for the interface included when writing a pcapng
157 format file. By default no name is defined.
158 -o hex|oct|dec
160 Specify the radix for the offsets (hex, octal or decimal). Defaults
162 to hex. This corresponds to the -A option for od.
163 -q
165 Be completely quiet during the process.
167 -s <srcport>,<destport>,<tag>
169 Include dummy SCTP headers before each packet. Specify, in decimal,
171 the source and destination SCTP ports, and verification tag, for
172 the packet. Use this option if your dump is the SCTP payload of a
173 packet but does not include any SCTP, IP or Ethernet headers. Note
174 that appropriate Ethernet and IP headers are automatically also
175 included with each packet. A CRC32C checksum will be put into the
176 SCTP header.
177 -S <srcport>,<destport>,<ppi>
179 Include dummy SCTP headers before each packet. Specify, in decimal,
181 the source and destination SCTP ports, and a verification tag of 0,
182 for the packet, and prepend a dummy SCTP DATA chunk header with a
183 payload protocol identifier if ppi. Use this option if your dump is
184 the SCTP payload of a packet but does not include any SCTP, IP or
185 Ethernet headers. Note that appropriate Ethernet and IP headers are
186 automatically included with each packet. A CRC32C checksum will be
187 put into the SCTP header.
188 -t <timefmt>
190 Treats the text before the packet as a date/time code; timefmt is a
192 format string of the sort supported by strptime(3). Example: The
193 time "10:15:14.5476" has the format code "%H:%M:%S."
194 NOTE: The subsecond component delimiter must be specified (.) but
196 no pattern is required; the remaining number is assumed to be
197 fractions of a second.
198 NOTE: Date/time fields from the current date/time are used as the
200 default for unspecified fields.
201 -T <srcport>,<destport>
203 Include dummy TCP headers before each packet. Specify the source
205 and destination TCP ports for the packet in decimal. Use this
206 option if your dump is the TCP payload of a packet but does not
207 include any TCP, IP or Ethernet headers. Note that appropriate
208 Ethernet and IP headers are automatically also included with each
209 packet. Sequence numbers will start at 0.
210 -u <srcport>,<destport>
212 Include dummy UDP headers before each packet. Specify the source
214 and destination UDP ports for the packet in decimal. Use this
215 option if your dump is the UDP payload of a packet but does not
216 include any UDP, IP or Ethernet headers. Note that appropriate
217 Ethernet and IP headers are automatically also included with each
218 packet. Example: -u1000,69 to make the packets look like TFTP/UDP
219 packets.
220 -v
222 Print the version and exit.
224 -4 <srcip>,<destip>
226 Prepend dummy IP header with specified IPv4 dest and source
228 address. This option should be accompanied by one of the following
229 options: -i, -s, -S, -T, -u Use this option to apply "custom" IP
230 addresses. Example: -4 10.0.0.1,10.0.0.2 to use 10.0.0.1 and
231 10.0.0.2 for all IP packets.
232 -6 <srcip>,<destip>
234 Prepend dummy IP header with specified IPv6 dest and source
236 address. This option should be accompanied by one of the following
237 options: -i, -s, -S, -T, -u Use this option to apply "custom" IP
238 addresses. Example: -6
239 fe80::202:b3ff:fe1e:8329,2001:0db8:85a3::8a2e:0370:7334 to use
240 fe80::202:b3ff:fe1e:8329 and 2001:0db8:85a3::8a2e:0370:7334 for all
241 IP packets.
242
244 od(1), pcap(3), wireshark(1), tshark(1), dumpcap(1), mergecap(1),
245 editcap(1), strptime(3), pcap-filter(7) or tcpdump(8)
246
248 This is the manual page for Text2pcap 3.6.2. Text2pcap is part of the
249 Wireshark distribution. The latest version of Wireshark can be found at
250 https://www.wireshark.org.
251
253 Original Author
254 Ashok Narayanan <ashokn[AT]cisco.com>
255 2022-02-16 TEXT2PCAP(1)