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2 =head1 NAME
3  
4 text2pcap - Generate a capture file from an ASCII hexdump of packets
5  
6 =head1 SYNOPSIS
7  
8 B<text2pcap>
9 S<[ B<-a> ]>
10 S<[ B<-d> ]>
11 S<[ B<-D> ]>
12 S<[ B<-e> E<lt>l3pidE<gt> ]>
13 S<[ B<-h> ]>
14 S<[ B<-i> E<lt>protoE<gt> ]>
15 S<[ B<-l> E<lt>typenumE<gt> ]>
16 S<[ B<-n> ]>
17 S<[ B<-m> E<lt>max-packetE<gt> ]>
18 S<[ B<-o> hex|oct|dec ]>
19 S<[ B<-q> ]>
20 S<[ B<-s> E<lt>srcportE<gt>,E<lt>destportE<gt>,E<lt>tagE<gt> ]>
21 S<[ B<-S> E<lt>srcportE<gt>,E<lt>destportE<gt>,E<lt>ppiE<gt> ]>
22 S<[ B<-t> E<lt>timefmtE<gt> ]>
23 S<[ B<-T> E<lt>srcportE<gt>,E<lt>destportE<gt> ]>
24 S<[ B<-u> E<lt>srcportE<gt>,E<lt>destportE<gt> ]>
25 S<[ B<-v> ]>
26 E<lt>I<infile>E<gt>|-
27 E<lt>I<outfile>E<gt>|-
28  
29 =head1 DESCRIPTION
30  
31 B<Text2pcap> is a program that reads in an ASCII hex dump and writes the
32 data described into a B<pcap> capture file. B<text2pcap> can
33 read hexdumps with multiple packets in them, and build a capture file of
34 multiple packets. B<text2pcap> is also capable of generating dummy
35 Ethernet, IP and UDP, TCP, or SCTP headers, in order to build fully
36 processable packet dumps from hexdumps of application-level data only.
37  
38 B<Text2pcap> understands a hexdump of the form generated by I<od -Ax
39 -tx1 -v>. In other words, each byte is individually displayed, with
40 spaces separating the bytes from each other. Each line begins with an
41 offset describing the position in the file, with a space separating it
42 from the following bytes. The offset is a hex number (can also be octal
43 or decimal - see B<-o>), of more than two hex digits. Here is a sample
44 dump that B<text2pcap> can recognize:
45  
46 000000 00 0e b6 00 00 02 00 0e b6 00 00 01 08 00 45 00
47 000010 00 28 00 00 00 00 ff 01 37 d1 c0 00 02 01 c0 00
48 000020 02 02 08 00 a6 2f 00 01 00 01 48 65 6c 6c 6f 20
49 000030 57 6f 72 6c 64 21
50 000036
51  
52 There is no limit on the width or number of bytes per line. Also the
53 text dump at the end of the line is ignored. Bytes/hex numbers can be
54 uppercase or lowercase. Any text before the offset is ignored,
55 including email forwarding characters '>'. Any lines of text between
56 the bytestring lines is ignored. The offsets are used to track the
57 bytes, so offsets must be correct. Any line which has only bytes
58 without a leading offset is ignored. An offset is recognized as being
59 a hex number longer than two characters. Any text after the bytes is
60 ignored (e.g. the character dump). Any hex numbers in this text are
61 also ignored. An offset of zero is indicative of starting a new
62 packet, so a single text file with a series of hexdumps can be
63 converted into a packet capture with multiple packets. Packets may be
64 preceded by a timestamp. These are interpreted according to the format
65 given on the command line (see B<-t>). If not, the first packet
66 is timestamped with the current time the conversion takes place. Multiple
67 packets are written with timestamps differing by one microsecond each.
68 In general, short of these restrictions, B<text2pcap> is pretty liberal
69 about reading in hexdumps and has been tested with a variety of
70 mangled outputs (including being forwarded through email multiple
71 times, with limited line wrap etc.)
72  
73 There are a couple of other special features to note. Any line where
74 the first non-whitespace character is '#' will be ignored as a
75 comment. Any line beginning with #TEXT2PCAP is a directive and options
76 can be inserted after this command to be processed by
77 B<text2pcap>. Currently there are no directives implemented; in the
78 future, these may be used to give more fine grained control on the
79 dump and the way it should be processed e.g. timestamps, encapsulation
80 type etc.
81  
82 B<Text2pcap> also allows the user to read in dumps of
83 application-level data, by inserting dummy L2, L3 and L4 headers
84 before each packet. The user can elect to insert Ethernet headers,
85 Ethernet and IP, or Ethernet, IP and UDP/TCP/SCTP headers before each
86 packet. This allows Wireshark or any other full-packet decoder to
87 handle these dumps.
88  
89 =head1 OPTIONS
90  
91 =over 4
92  
93 =item -a
94  
95 Enables ASCII text dump identification. It allows one to identify the start of
96 the ASCII text dump and not include it in the packet even if it looks like HEX.
97  
98 B<NOTE:> Do not enable it if the input file does not contain the ASCII text dump.
99  
100 =item -d
101  
102 Displays debugging information during the process. Can be used
103 multiple times to generate more debugging information.
104  
105 =item -D
106  
107 The text before the packet starts either with an I or O indicating that
108 the packet is inbound or outbound.
109 This is only stored if the output format is PCAP-NG.
110  
111 =item -e E<lt>l3pidE<gt>
112  
113 Include a dummy Ethernet header before each packet. Specify the L3PID
114 for the Ethernet header in hex. Use this option if your dump has Layer
115 3 header and payload (e.g. IP header), but no Layer 2
116 encapsulation. Example: I<-e 0x806> to specify an ARP packet.
117  
118 For IP packets, instead of generating a fake Ethernet header you can
119 also use I<-l 101> to indicate a raw IP packet to Wireshark. Note that
120 I<-l 101> does not work for any non-IP Layer 3 packet (e.g. ARP),
121 whereas generating a dummy Ethernet header with I<-e> works for any
122 sort of L3 packet.
123  
124 =item -h
125  
126 Displays a help message.
127  
128 =item -i E<lt>protoE<gt>
129  
130 Include dummy IP headers before each packet. Specify the IP protocol
131 for the packet in decimal. Use this option if your dump is the payload
132 of an IP packet (i.e. has complete L4 information) but does not have
133 an IP header with each packet. Note that an appropriate Ethernet header
134 is automatically included with each packet as well.
135 Example: I<-i 46> to specify an RSVP packet (IP protocol 46). See
136 L<http://www.iana.org/assignments/protocol-numbers/protocol-numbers.xhtml> for
137 the complete list of assigned internet protocol numbers.
138  
139 =item -l
140  
141 Specify the link-layer header type of this packet. Default is Ethernet
142 (1). See L<http://www.tcpdump.org/linktypes.html> for the complete list
143 of possible encapsulations. Note that this option should be used if
144 your dump is a complete hex dump of an encapsulated packet and you wish
145 to specify the exact type of encapsulation. Example: I<-l 7> for ARCNet
146 packets encapsulated BSD-style.
147  
148 =item -m E<lt>max-packetE<gt>
149  
150 Set the maximum packet length, default is 65535.
151 Useful for testing various packet boundaries when only an application
152 level datastream is available. Example:
153  
154 I<od -Ax -tx1 -v stream | text2pcap -m1460 -T1234,1234 - stream.pcap>
155  
156 will convert from plain datastream format to a sequence of Ethernet
157 TCP packets.
158  
159 =item -n
160  
161 Write PCAP-NG file instead of a PCAP.
162  
163 =item -o hex|oct|dec
164  
165 Specify the radix for the offsets (hex, octal or decimal). Defaults to
166 hex. This corresponds to the C<-A> option for I<od>.
167  
168 =item -q
169  
170 Be completely quiet during the process.
171  
172 =item -s E<lt>srcportE<gt>,E<lt>destportE<gt>,E<lt>tagE<gt>
173  
174 Include dummy SCTP headers before each packet. Specify, in decimal, the
175 source and destination SCTP ports, and verification tag, for the packet.
176 Use this option if your dump is the SCTP payload of a packet but does
177 not include any SCTP, IP or Ethernet headers. Note that appropriate
178 Ethernet and IP headers are automatically also included with each
179 packet. A CRC32C checksum will be put into the SCTP header.
180  
181 =item -S E<lt>srcportE<gt>,E<lt>destportE<gt>,E<lt>ppiE<gt>
182  
183 Include dummy SCTP headers before each packet. Specify, in decimal, the
184 source and destination SCTP ports, and a verification tag of 0, for the
185 packet, and prepend a dummy SCTP DATA chunk header with a payload
186 protocol identifier if I<ppi>. Use this option if your dump is the SCTP
187 payload of a packet but does not include any SCTP, IP or Ethernet
188 headers. Note that appropriate Ethernet and IP headers are
189 automatically included with each packet. A CRC32C checksum will be put
190 into the SCTP header.
191  
192 =item -t E<lt>timefmtE<gt>
193  
194 Treats the text before the packet as a date/time code; I<timefmt> is a
195 format string of the sort supported by strptime(3).
196 Example: The time "10:15:14.5476" has the format code "%H:%M:%S."
197  
198 B<NOTE:> The subsecond component delimiter must be specified (.) but no
199 pattern is required; the remaining number is assumed to be fractions of
200 a second.
201  
202 B<NOTE:> Date/time fields from the current date/time are
203 used as the default for unspecified fields.
204  
205 =item -T E<lt>srcportE<gt>,E<lt>destportE<gt>
206  
207 Include dummy TCP headers before each packet. Specify the source and
208 destination TCP ports for the packet in decimal. Use this option if
209 your dump is the TCP payload of a packet but does not include any TCP,
210 IP or Ethernet headers. Note that appropriate Ethernet and IP headers
211 are automatically also included with each packet.
212 Sequence numbers will start at 0.
213  
214 =item -u E<lt>srcportE<gt>,E<lt>destportE<gt>
215  
216 Include dummy UDP headers before each packet. Specify the source and
217 destination UDP ports for the packet in decimal. Use this option if
218 your dump is the UDP payload of a packet but does not include any UDP,
219 IP or Ethernet headers. Note that appropriate Ethernet and IP headers
220 are automatically also included with each packet.
221 Example: I<-u1000,69> to make the packets look like TFTP/UDP packets.
222  
223 =item -v
224  
225 Print the version and exit.
226  
227 =item -4 E<lt>srcipE<gt>,E<lt>destipE<gt>
228  
229 Prepend dummy IP header with specified IPv4 dest and source address.
230 This option should be accompanied by one of the following options: -i, -s, -S, -T, -u
231 Use this option to apply "custom" IP addresses.
232 Example: I<-4 10.0.0.1,10.0.0.2> to use 10.0.0.1 and 10.0.0.2 for all IP packets.
233  
234 =item -6 E<lt>srcipE<gt>,E<lt>destipE<gt>
235  
236 Prepend dummy IP header with specified IPv6 dest and source address.
237 This option should be accompanied by one of the following options: -i, -s, -S, -T, -u
238 Use this option to apply "custom" IP addresses.
239 Example: I<-6 fe80:0:0:0:202:b3ff:fe1e:8329, 2001:0db8:85a3:0000:0000:8a2e:0370:7334> to
240 use fe80:0:0:0:202:b3ff:fe1e:8329 and 2001:0db8:85a3:0000:0000:8a2e:0370:7334 for all IP packets.
241  
242 =back
243  
244 =head1 SEE ALSO
245  
246 od(1), pcap(3), wireshark(1), tshark(1), dumpcap(1), mergecap(1),
247 editcap(1), strptime(3), pcap-filter(7) or tcpdump(8)
248  
249 =head1 NOTES
250  
251 B<Text2pcap> is part of the B<Wireshark> distribution. The latest version
252 of B<Wireshark> can be found at L<https://www.wireshark.org>.
253  
254 =head1 AUTHORS
255  
256 Ashok Narayanan <ashokn[AT]cisco.com>