User Guide

File Input / Output and Printing

Figure 5.9. "Merge" - old GTK version

Unix/Linux: GTK version < 2.4

This is the file open dialog of former Gimp/

GNOME versions - plus some Wireshark

extensions.

5.5. Import text file

Wireshark can read in an ASCII hex dump and write the data described into a temporary libpcap capture

file. It can read hex dumps with multiple packets in them, and build a capture file of multiple packets. It

is also capable of generating dummy Ethernet, IP and UDP, TCP, or SCTP headers, in order to build fully

processable packet dumps from hexdumps of application-level data only.

Wireshark understands a hexdump of the form generated by od -Ax -tx1 -v. 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 or decimal), of more than two hex digits. Here

is a sample dump that can be imported:

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. Packets may be preceded by a timestamp. These are interpreted

according to the format given. If not the first packet is timestamped with the current time the import takes

place. Multiple packets are read in with timestamps differing by one microsecond each. In general, short of

these restrictions, Wireshark 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 Wireshark. 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. Wireshark 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