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|
<!-- EUG Appendix Tools -->
<!-- $Id$ -->
<appendix id="AppTools">
<title>Related command line tools</title>
<section id="AppToolsIntroduction">
<title>Introduction</title>
<para>
Beside the Ethereal GUI application, there are some command line tools,
which can be helpful for doing some more specialized things. These tools
will be described in this chapter.
</para>
</section>
<section id="AppToolstcpdump">
<title><command>tcpdump</command>: Capturing with tcpdump for viewing
with Ethereal</title>
<para>
There are occasions when you want to capture packets using
<command>tcpdump</command> rather than <command>ethereal</command>,
especially when you want to do a remote capture and do not want the
network load associated with running Ethereal remotely (not to
mention all the X traffic polluting your capture).
</para>
<para>
However, the default <command>tcpdump</command> parameters result in a
capture file where each packet is truncated, because
<command>tcpdump</command>, by default, does only capture the first 68
bytes of each packet.
</para>
<para>
To ensure that you capture complete packets, use the following command:
<programlisting>
tcpdump -i <interface> -s 1500 -w <some-file>
</programlisting>
You will have to specify the correct <command>interface</command> and
the name of a <command>file</command> to save into. In addition,
you will have to terminate the capture with ^C when you believe you
have captured enough packets.
</para>
<note><title>Note!</title>
<para>
tcpdump is not part of the Ethereal distribution. You can get it from:
<ulink url="http://www.tcpdump.org">http://www.tcpdump.org</ulink> for various
platforms.
</para>
</note>
</section>
<section id="AppToolstethereal">
<title><command>tethereal</command>: Terminal-based Ethereal</title>
<para>
<application>Tethereal</application> is a terminal oriented version
of ethereal designed for capturing and displaying packets when an
interactive user interface isn't necessary or available. It supports
the same options as <command>ethereal</command>. For more
information on <command>tethereal</command>, see the manual pages
(<command>man tethereal</command>).
</para>
</section>
<section id="AppToolscapinfos">
<title><command>capinfos</command>: Print information about capture files
</title>
<para>
Included with Wireshark is a small utility called
<command>capinfos</command>, which is a command-line utility to
print information about binary capture files.
</para>
<para>
<example id="AppToolscapinfosEx">
<title>Help information available from capinfos</title>
<programlisting>
$ capinfos -h
Usage: capinfos [-t] [-c] [-s] [-d] [-u] [-a] [-e] [-y]
[-i] [-z] [-h] <capfile>
where -t display the capture type of <capfile>
-c count the number of packets
-s display the size of the file
-d display the total length of all packets in the file
(in bytes)
-u display the capture duration (in seconds)
-a display the capture start time
-e display the capture end time
-y display average data rate (in bytes)
-i display average data rate (in bits)
-z display average packet size (in bytes)
-h produces this help listing.
If no data flags are given, default is to display all statistics
</programlisting>
</example>
</para>
</section>
<section id="AppToolseditcap">
<title><command>editcap</command>: Edit capture files</title>
<para>
Included with Wireshark is a small utility called
<command>editcap</command>, which is a command-line utility for
working with capture files. Its main function is to remove
packets from capture files, but it can also be used to convert
capture files from one format to another, as well as print
information about capture files.
</para>
<para>
<example id="AppToolseditcapEx">
<title>Help information available from editcap</title>
<programlisting>
$ editcap.exe -h
Usage: editcap [-r] [-h] [-v] [-T <encap type>] [-E <probability>]
[-F <capture type>]> [-s <snaplen>] [-t <time adjustment>]
<infile> <outfile> [ <record#>[-<record#>] ... ]
where
-E <probability> specifies the probability (between 0 and 1)
that a particular byte will will have an error.
-F <capture type> specifies the capture file type to write:
libpcap - libpcap (tcpdump, Ethereal, etc.)
rh6_1libpcap - RedHat Linux 6.1 libpcap (tcpdump)
suse6_3libpcap - SuSE Linux 6.3 libpcap (tcpdump)
modlibpcap - modified libpcap (tcpdump)
nokialibpcap - Nokia libpcap (tcpdump)
lanalyzer - Novell LANalyzer
ngsniffer - Network Associates Sniffer (DOS-based)
snoop - Sun snoop
netmon1 - Microsoft Network Monitor 1.x
netmon2 - Microsoft Network Monitor 2.x
ngwsniffer_1_1 - Network Associates Sniffer (Windows-based) 1.1
ngwsniffer_2_0 - Network Associates Sniffer (Windows-based) 2.00x
nettl - HP-UX nettl trace
visual - Visual Networks traffic capture
5views - Accellent 5Views capture
niobserverv9 - Network Instruments Observer version 9
default is libpcap
-h produces this help listing.
-r specifies that the records specified should be kept, not deleted,
default is to delete
-s <snaplen> specifies that packets should be truncated to
<snaplen> bytes of data
-t <time adjustment> specifies the time adjustment
to be applied to selected packets
-T <encap type> specifies the encapsulation type to use:
ether - Ethernet
tr - Token Ring
slip - SLIP
ppp - PPP
fddi - FDDI
fddi-swapped - FDDI with bit-swapped MAC addresses
rawip - Raw IP
arcnet - ARCNET
arcnet_linux - Linux ARCNET
atm-rfc1483 - RFC 1483 ATM
linux-atm-clip - Linux ATM CLIP
lapb - LAPB
atm-pdus - ATM PDUs
atm-pdus-untruncated - ATM PDUs - untruncated
null - NULL
ascend - Lucent/Ascend access equipment
isdn - ISDN
ip-over-fc - RFC 2625 IP-over-Fibre Channel
ppp-with-direction - PPP with Directional Info
ieee-802-11 - IEEE 802.11 Wireless LAN
prism - IEEE 802.11 plus Prism II monitor mode header
ieee-802-11-radio - IEEE 802.11 Wireless LAN with radio information
ieee-802-11-radiotap - IEEE 802.11 plus radiotap WLAN header
ieee-802-11-avs - IEEE 802.11 plus AVS WLAN header
linux-sll - Linux cooked-mode capture
frelay - Frame Relay
frelay-with-direction - Frame Relay with Directional Info
chdlc - Cisco HDLC
ios - Cisco IOS internal
ltalk - Localtalk
pflog-old - OpenBSD PF Firewall logs, pre-3.4
hhdlc - HiPath HDLC
docsis - Data Over Cable Service Interface Specification
cosine - CoSine L2 debug log
whdlc - Wellfleet HDLC
sdlc - SDLC
tzsp - Tazmen sniffer protocol
enc - OpenBSD enc(4) encapsulating interface
pflog - OpenBSD PF Firewall logs
chdlc-with-direction - Cisco HDLC with Directional Info
bluetooth-h4 - Bluetooth H4
mtp2 - SS7 MTP2
mtp3 - SS7 MTP3
irda - IrDA
user0 - USER 0
user1 - USER 1
user2 - USER 2
user3 - USER 3
user4 - USER 4
user5 - USER 5
user6 - USER 6
user7 - USER 7
user8 - USER 8
user9 - USER 9
user10 - USER 10
user11 - USER 11
user12 - USER 12
user13 - USER 13
user14 - USER 14
user15 - USER 15
symantec - Symantec Enterprise Firewall
ap1394 - Apple IP-over-IEEE 1394
bacnet-ms-tp - BACnet MS/TP
raw-icmp-nettl - Raw ICMP with nettl headers
raw-icmpv6-nettl - Raw ICMPv6 with nettl headers
gprs-llc - GPRS LLC
juniper-atm1 - Juniper ATM1
juniper-atm2 - Juniper ATM2
redback - Redback SmartEdge
rawip-nettl - Raw IP with nettl headers
ether-nettl - Ethernet with nettl headers
tr-nettl - Token Ring with nettl headers
fddi-nettl - FDDI with nettl headers
unknown-nettl - Unknown link-layer type with nettl headers
mtp2-with-phdr - MTP2 with pseudoheader
juniper-pppoe - Juniper PPPoE
gcom-tie1 - GCOM TIE1
gcom-serial - GCOM Serial
x25-nettl - X25 with nettl headers
default is the same as the input file
-v specifies verbose operation, default is silent
A range of records can be specified as well
</programlisting>
</example>
Where each option has the following meaning:
<variablelist>
<varlistentry><term><command>-r</command></term>
<listitem>
<para>
This option specifies that the frames listed should be kept,
not deleted. The default is to delete the listed frames.
</para>
</listitem>
</varlistentry>
<varlistentry><term><command>-h</command></term>
<listitem><para>This option provides help.</para></listitem>
</varlistentry>
<varlistentry><term><command>-v</command></term>
<listitem>
<para>
This option specifies verbose operation. The default is
silent operation.
</para>
</listitem>
</varlistentry>
<varlistentry><term><command>-T {encap type}</command></term>
<listitem>
<para>
This option specifies the frame encapsulation type to use.
</para>
<para>
It is mainly for converting funny captures to something
that Ethereal can deal with.
</para>
<para>
The default frame
encapsulation type is the same as the input encapsulation.
</para>
</listitem>
</varlistentry>
<varlistentry><term><command>-F {capture type}</command></term>
<listitem>
<para>
This option specifies the capture file format to write
the output file in.
</para>
<para>
The default is libpcap format.
</para>
</listitem>
</varlistentry>
<varlistentry><term><command>-s {snaplen}</command></term>
<listitem>
<para>
Specifies that packets should be truncated to {snaplen} bytes of data.
</para>
</listitem>
</varlistentry>
<varlistentry><term><command>-t {time adjustment}</command></term>
<listitem>
<para>
Specifies the time adjustment to be applied to selected packets.
</para>
</listitem>
</varlistentry>
<varlistentry><term><command>{infile}</command></term>
<listitem>
<para>
This parameter specifies the input file to use. It must be
present.
</para>
</listitem>
</varlistentry>
<varlistentry><term><command>{outfile}</command></term>
<listitem>
<para>
This parameter specifies the output file to use. It must
be present.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><command>[record#[-][record# ...]]</command></term>
<listitem>
<para>
This optional parameter specifies the records to include
or exclude (depending on the <command>-r</command> option.
You can specify individual records or a range of records.
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
</section>
<section id="AppToolsmergecap">
<title><command>mergecap</command>:
Merging multiple capture files into one
</title>
<para>
Mergecap is a program that combines multiple saved capture files
into a single output file specified by the -w argument. Mergecap
knows how to read libpcap capture files, including those of tcpdump.
In addition, Mergecap can read capture files from snoop (including
Shomiti) and atmsnoop, LanAlyzer, Sniffer (compressed or
uncompressed), Microsoft Network Monitor, AIX's iptrace, NetXray,
Sniffer Pro, RADCOM's WAN/LAN analyzer, Lucent/Ascend router debug
output, HP-UX's nettl, and the dump output from Toshiba's ISDN
routers. There is no need to tell Mergecap what type of file you are
reading; it will determine the file type by itself. Mergecap is also
capable of reading any of these file formats if they are compressed
using gzip. Mergecap recognizes this directly from the file; the '.gz'
extension is not required for this purpose.
</para>
<para>
By default, it writes the capture file in libpcap format, and writes
all of the packets in both input capture files to the output file.
The -F flag can be used to specify the format in which to write the
capture file; it can write the file in libpcap format (standard
libpcap format, a modified format used by some patched versions of
libpcap, the format used by Red Hat Linux 6.1, or the format used
by SuSE Linux 6.3), snoop format, uncompressed Sniffer format,
Microsoft Network Monitor 1.x format, and the format used by
Windows-based versions of the Sniffer software.
</para>
<para>
Packets from the input files are merged in chronological order based
on each frame's timestamp, unless the -a flag is specified. Mergecap
assumes that frames within a single capture file are already stored
in chronological order. When the -a flag is specified, packets are
copied directly from each input file to the output file, independent
of each frame's timestamp.
</para>
<para>
If the -s flag is used to specify a snapshot length, frames in the
input file with more captured data than the specified snapshot length
will have only the amount of data specified by the snapshot length
written to the output file. This may be useful if the program that
is to read the output file cannot handle packets larger than a
certain size (for example, the versions of snoop in Solaris 2.5.1 and
Solaris 2.6 appear to reject Ethernet frames larger than the standard
Ethernet MTU, making them incapable of handling gigabit Ethernet
captures if jumbo frames were used).
</para>
<para>
If the -T flag is used to specify an encapsulation type, the
encapsulation type of the output capture file will be forced to
the specified type, rather than being the type appropriate to the
encapsulation type of the input capture file. Note that this merely
forces the encapsulation type of the output file to be the specified
type; the packet headers of the packets will not be translated from the
encapsulation type of the input capture file to the specified
encapsulation type (for example, it will not translate an Ethernet
capture to an FDDI capture if an Ethernet capture is read
and '-T fddi' is specified).
</para>
<example id="AppToolsmergecapEx">
<title>Help information available from mergecap</title>
<programlisting>
$ mergecap.exe -h
mergecap version 0.10.5
Usage: mergecap [-hva] [-s <snaplen>] [-T <encap type>]
[-F <capture type>] -w <outfile> <infile> [...]
where -h produces this help listing.
-v verbose operation, default is silent
-a files should be concatenated, not merged
Default merges based on frame timestamps
-s <snaplen>: truncate packets to <snaplen> bytes of data
-w <outfile>: sets output filename to <outfile>
-T <encap type> encapsulation type to use:
ether - Ethernet
tr - Token Ring
slip - SLIP
ppp - PPP
fddi - FDDI
fddi-swapped - FDDI with bit-swapped MAC addresses
rawip - Raw IP
arcnet - ARCNET
arcnet_linux - Linux ARCNET
atm-rfc1483 - RFC 1483 ATM
linux-atm-clip - Linux ATM CLIP
lapb - LAPB
atm-pdus - ATM PDUs
atm-pdus-untruncated - ATM PDUs - untruncated
null - NULL
ascend - Lucent/Ascend access equipment
isdn - ISDN
ip-over-fc - RFC 2625 IP-over-Fibre Channel
ppp-with-direction - PPP with Directional Info
ieee-802-11 - IEEE 802.11 Wireless LAN
prism - IEEE 802.11 plus Prism II monitor mode header
ieee-802-11-radio - IEEE 802.11 Wireless LAN with radio information
ieee-802-11-bsd - IEEE 802.11 plus BSD WLAN header
ieee-802-11-avs - IEEE 802.11 plus AVS WLAN header
linux-sll - Linux cooked-mode capture
frelay - Frame Relay
frelay-with-direction - Frame Relay with Directional Info
chdlc - Cisco HDLC
ios - Cisco IOS internal
ltalk - Localtalk
pflog-old - OpenBSD PF Firewall logs, pre-3.4
hhdlc - HiPath HDLC
docsis - Data Over Cable Service Interface Specification
cosine - CoSine L2 debug log
whdlc - Wellfleet HDLC
sdlc - SDLC
tzsp - Tazmen sniffer protocol
enc - OpenBSD enc(4) encapsulating interface
pflog - OpenBSD PF Firewall logs
chdlc-with-direction - Cisco HDLC with Directional Info
bluetooth-h4 - Bluetooth H4
mtp2 - SS7 MTP2
mtp3 - SS7 MTP3
irda - IrDA
user0 - USER 0
user1 - USER 1
user2 - USER 2
user3 - USER 3
user4 - USER 4
user5 - USER 5
user6 - USER 6
user7 - USER 7
user8 - USER 8
user9 - USER 9
user10 - USER 10
user11 - USER 11
user12 - USER 12
user13 - USER 13
user14 - USER 14
user15 - USER 15
symantec - Symantec Enterprise Firewall
ap1394 - Apple IP-over-IEEE 1394
bacnet-ms-tp - BACnet MS/TP
default is the same as the first input file
-F <capture type> capture file type to write:
libpcap - libpcap (tcpdump, Ethereal, etc.)
rh6_1libpcap - RedHat Linux 6.1 libpcap (tcpdump)
suse6_3libpcap - SuSE Linux 6.3 libpcap (tcpdump)
modlibpcap - modified libpcap (tcpdump)
nokialibpcap - Nokia libpcap (tcpdump)
lanalyzer - Novell LANalyzer
ngsniffer - Network Associates Sniffer (DOS-based)
snoop - Sun snoop
netmon1 - Microsoft Network Monitor 1.x
netmon2 - Microsoft Network Monitor 2.x
ngwsniffer_1_1 - Network Associates Sniffer (Windows-based) 1.1
ngwsniffer_2_0 - Network Associates Sniffer (Windows-based) 2.00x
visual - Visual Networks traffic capture
5views - Accellent 5Views capture
niobserverv9 - Network Instruments Observer version 9
default is libpcap
</programlisting>
</example>
<variablelist>
<varlistentry><term><command>-h</command></term>
<listitem>
<para>Prints the version and options and exits.</para>
</listitem>
</varlistentry>
<varlistentry><term><command>-v</command></term>
<listitem>
<para>
Causes <command>mergecap</command> to print a number of messages
while it's working.
</para>
</listitem>
</varlistentry>
<varlistentry><term><command>-a</command></term>
<listitem>
<para>
Causes the frame timestamps to be ignored, writing all packets
from the first input file followed by all packets from the second
input file. By default, when <command>-a</command> is not
specified, the contents
of the input files are merged in chronological order based on
each frame's timestamp. Note: when merging, mergecap assumes
that packets within a capture file are already in chronological
order.
</para>
</listitem>
</varlistentry>
<varlistentry><term><command>-s</command></term>
<listitem>
<para>Sets the snapshot length to use when writing the data.</para>
</listitem>
</varlistentry>
<varlistentry><term><command>-w</command></term>
<listitem>
<para>Sets the output filename.</para>
</listitem>
</varlistentry>
<varlistentry><term><command>-T</command></term>
<listitem>
<para>
Sets the packet encapsulation type of the output capture file.
</para>
</listitem>
</varlistentry>
<varlistentry><term><command>-F</command></term>
<listitem>
<para>Sets the file format of the output capture file.</para>
</listitem>
</varlistentry>
</variablelist>
<para>
A simple example merging <filename>dhcp-capture.libpcap</filename>
and <filename>imap-1.libpcap</filename> into
<filename>outfile.libpcap</filename> is shown below.
</para>
<example id="AppToolsmergecapExSimple">
<title>Simple example of using mergecap</title>
<programlisting>$ mergecap -w outfile.libpcap dhcp-capture.libpcap imap-1.libpcap
</programlisting>
</example>
</section>
<section id="AppToolstext2pcap" >
<title><command>text2pcap</command>: Converting ASCII hexdumps to network
captures
</title>
<para>
There may be some occasions when you wish to convert a hex dump of some
network traffic into a libpcap file.</para>
<para>
<command>Text2pcap</command> 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 headers, in order to build fully
processable packet dumps from hexdumps of application-level data only.
</para>
<para>
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:
</para>
<programlisting>
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 ........
</programlisting>
<para>
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.)
</para>
<para>
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.
</para>
<para>
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 headers before each packet. This allows Ethereal
or any other full-packet decoder to handle these dumps.
</para>
<example id="AppToolstext2pcapEx">
<title>Help information available for text2pcap</title>
<programlisting>
$ text2pcap.exe -h
Usage: text2pcap.exe [-h] [-d] [-q] [-o h|o] [-l typenum] [-e l3pid] [-i proto]
[-m max-packet] [-u srcp,destp] [-T srcp,destp] [-s srcp,destp,tag]
[-S srcp,destp,tag] [-t timefmt] <input-filename> <output-filename>
where <input-filename> specifies input filename (use - for standard input)
<output-filename> specifies output filename (use - for standard output)
[options] are one or more of the following
-h : Display this help message
-d : Generate detailed debug of parser states
-o hex|oct : Parse offsets as (h)ex or (o)ctal. Default is hex
-l typenum : Specify link-layer type number. Default is 1 (Ethernet).
See net/bpf.h for list of numbers.
-q : Generate no output at all (automatically turns off -d)
-e l3pid : Prepend dummy Ethernet II header with specified L3PID (in
HEX)
Example: -e 0x800
-i proto : Prepend dummy IP header with specified IP protocol (in
DECIMAL).
Automatically prepends Ethernet header as well.
Example: -i 46
-m max-packet : Max packet length in output, default is 64000
-u srcp,destp : Prepend dummy UDP header with specified dest and source ports
(in DECIMAL).
Automatically prepends Ethernet and IP headers as well
Example: -u 30,40
-T srcp,destp : Prepend dummy TCP header with specified dest and source ports
(in DECIMAL).
Automatically prepends Ethernet and IP headers as well
Example: -T 50,60
-s srcp,dstp,tag: Prepend dummy SCTP header with specified dest/source ports
and verification tag (in DECIMAL).
Automatically prepends Ethernet and IP headers as well
Example: -s 30,40,34
-S srcp,dstp,ppi: Prepend dummy SCTP header with specified dest/source ports
and verification tag 0. It also prepends a dummy SCTP DATA
chunk header with payload protocol identifier ppi.
Example: -S 30,40,34
-t timefmt : Treats the text before the packet as a date/time code; the
specified argument is a format string of the sort supported
by strptime.
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.
</programlisting>
</example>
<variablelist>
<varlistentry><term><command>-w <filename></command></term>
<listitem>
<para>
Write the capture file generated by <command>text2pcap</command>
to <filename>. The default is to write to standard
output.
</para>
</listitem>
</varlistentry>
<varlistentry><term><command>-h</command></term>
<listitem>
<para>Display the help message</para>
</listitem>
</varlistentry>
<varlistentry><term><command>-d</command></term>
<listitem>
<para>
Displays debugging information during the process. Can be
used multiple times to generate more debugging information.
</para>
</listitem>
</varlistentry>
<varlistentry><term><command>-q</command></term>
<listitem>
<para>Be completely quiet during the process.</para>
</listitem>
</varlistentry>
<varlistentry><term><command>-o hex|oct</command></term>
<listitem>
<para> Specify the radix for the offsets (hex or octal). Defaults to
hex. This corresponds to the <command>-A</command> option for od.
</para>
</listitem>
</varlistentry>
<varlistentry><term><command>-l</command></term>
<listitem>
<para>
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.
</para>
</listitem>
</varlistentry>
<varlistentry><term><command>-e l3pid</command></term>
<listitem>
<para>
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.
</para>
<para>
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.
</para>
</listitem>
</varlistentry>
<varlistentry><term><command>-u srcport destport</command></term>
<listitem>
<para>
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.
</para>
</listitem>
</varlistentry>
</variablelist>
</section>
<section id="AppToolsidl2eth" >
<title><command>idl2eth</command>:
Creating dissectors from Corba IDL files
</title>
<para>
In an ideal world idl2eth would be mentioned in the users guide
in passing and documented in the developers guide. As the
developers guide
has not yet been completed it will be documented here.
</para>
<section>
<title>What is it?</title>
<para>
As you have probably guessed from the name,
<command>idl2eth</command> takes a
user specified IDL file and attempts to build a dissector that
can decode the IDL traffic over GIOP. The resulting file is
"C" code, that should compile okay as an ethereal dissector.
</para>
<para>
<command>idl2eth</command> basically parses the data struct given to
it by the omniidl compiler, and using the GIOP API available in
packet-giop.[ch], generates get_CDR_xxx calls to decode the
CORBA traffic on the wire.
</para>
<para>It consists of 4 main files.</para>
<variablelist>
<varlistentry><term><filename>README.idl2eth</filename></term>
<listitem>
<para>This document</para>
</listitem>
</varlistentry>
<varlistentry><term><filename>ethereal_be.py</filename></term>
<listitem>
<para>The main compiler backend</para>
</listitem>
</varlistentry>
<varlistentry><term><filename>ethereal_gen.py</filename></term>
<listitem>
<para>A helper class, that generates the C code.</para>
</listitem>
</varlistentry>
<varlistentry><term><filename>idl2eth</filename></term>
<listitem>
<para> A simple shell script wrapper that the end user should
use to generate the dissector from the IDL file(s).</para>
</listitem>
</varlistentry>
</variablelist>
</section>
<section>
<title>Why do this?</title>
<para>
It is important to understand what CORBA traffic looks
like over GIOP/IIOP, and to help build a tool that can assist
in troubleshooting CORBA interworking. This was especially the
case after seeing a lot of discussions about how particular
IDL types are represented inside an octet stream.
</para>
<para>
I have also had comments/feedback that this tool would be good for say
a CORBA class when teaching students what CORBA traffic looks like
"on the wire".
</para>
<para>
It is also COOL to work on a great Open Source project such as
the case with "Ethereal" (
<ulink url="http://www.ethereal.com">http://www.ethereal.com</ulink>
)
</para>
</section>
<section><title>How to use idl2eth</title>
<para>
To use the idl2eth to generate ethereal dissectors, you
need the following:
</para>
<orderedlist>
<title>Prerequisites to using idl2eth</title>
<listitem>
<para>
Python must be installed. See
<ulink url="http://python.org/"/>
</para>
</listitem>
<listitem>
<para>
omniidl from the the omniORB package must be available. See
<ulink url="http://omniorb.sourceforge.net/"/>
</para>
</listitem>
<listitem>
<para>
Of course you need ethereal installed to compile the
code and tweak it if required. idl2eth is part of the
standard Ethereal distribution
</para>
</listitem>
</orderedlist>
<para>
To use idl2eth to generate an ethereal dissector from an idl file
use the following procedure:
</para>
<orderedlist>
<title>
Procedure for converting a Corba idl file into an ethereal
dissector
</title>
<listitem>
<para>
To write the C code to stdout.
<programlisting>idl2eth <your file.idl></programlisting>
eg: <programlisting>idl2eth echo.idl</programlisting>
</para>
</listitem>
<listitem>
<para>
To write to a file, just redirect the output.
<programlisting>idl2eth echo.idl > packet-test-idl.c</programlisting>
You may wish to comment out the register_giop_user_module() code
and that will leave you with heuristic dissection.
</para>
</listitem>
</orderedlist>
<para>
If you don't want to use the shell script wrapper, then try
steps 3 or 4 instead.</para>
<orderedlist continuation="continues">
<listitem>
<para>To write the C code to stdout.
<programlisting>Usage: omniidl -p ./ -b ethereal_be <your file.idl></programlisting>
eg:
<programlisting>omniidl -p ./ -b ethereal_be echo.idl</programlisting>
</para>
</listitem>
<listitem>
<para>
To write to a file, just redirect the output.
<programlisting>omniidl -p ./ -b ethereal_be echo.idl > packet-test-idl.c</programlisting>
You may wish to comment out the register_giop_user_module() code
and that will leave you with heuristic dissection.
</para>
</listitem>
<listitem>
<para>
Copy the resulting C code to your ethereal src directory,
edit the 2 make files to include the packet-test-idl.c
<programlisting>
cp packet-test-idl.c /dir/where/ethereal/lives/
edit Makefile.am
edit Makefile.nmake
</programlisting>
</para>
</listitem>
<listitem>
<para>Run configure
<programlisting>./configure (or ./autogen.sh)</programlisting>
</para>
</listitem>
<listitem>
<para> Compile the code
<programlisting>make</programlisting>
</para>
</listitem>
<listitem>
<para>Good Luck !!</para>
</listitem>
</orderedlist>
</section>
<section><title>TODO</title>
<orderedlist>
<listitem>
<para>
Exception code not generated (yet), but can be added manually.
</para>
</listitem>
<listitem>
<para>
Enums not converted to symbolic values (yet), but can be added
manually.
</para>
</listitem>
<listitem>
<para>Add command line options etc</para>
</listitem>
<listitem>
<para>More I am sure :-)</para>
</listitem>
</orderedlist>
</section>
<section><title>Limitations</title>
<para>
See the TODO list inside <filename>packet-giop.c</filename>
</para>
</section>
<section><title>Notes</title>
<orderedlist>
<listitem>
<para>
The "-p ./" option passed to omniidl indicates that the
ethereal_be.py and ethereal_gen.py are residing in the
current directory. This may need
tweaking if you place these files somewhere else.
</para>
</listitem>
<listitem>
<para>
If it complains about being unable to find some modules
(eg tempfile.py),
you may want to check if PYTHONPATH is set correctly.
On my Linux box, it is PYTHONPATH=/usr/lib/python1.5/
</para>
</listitem>
</orderedlist>
</section>
</section>
</appendix>
<!-- End of EUG Appendix Tools -->
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