You can start Wireshark from the command line, but it can also be started from most Window managers as well. In this section we will look at starting it from the command line.
Wireshark supports a large number of command line parameters. To see what they are, simply enter the command wireshark -h and the help information shown in Example 10.1, “Help information available from Wireshark” (or something similar) should be printed.
Example 10.1. Help information available from Wireshark
Wireshark 2.1.0 (v2.1.0rc0-502-g328fbc0 from master) Interactively dump and analyze network traffic. See https://www.wireshark.org for more information. Usage: wireshark [options] ... [ <infile> ] Capture interface: -i <interface> name or idx of interface (def: first non-loopback) -f <capfilter|predef:> packet filter in libpcap filter syntax or predef:filtername - predefined filtername from GUI -s <snaplen> packet snapshot length (def: 65535) -p don't capture in promiscuous mode -k start capturing immediately (def: do nothing) -S update packet display when new packets are captured -l turn on automatic scrolling while -S is in use -I capture in monitor mode, if available -B <buffer size> size of kernel buffer (def: 2MB) -y <link type> link layer type (def: first appropriate) -D print list of interfaces and exit -L print list of link-layer types of iface and exit Capture stop conditions: -c <packet count> stop after n packets (def: infinite) -a <autostop cond.> ... duration:NUM - stop after NUM seconds filesize:NUM - stop this file after NUM KB files:NUM - stop after NUM files Capture output: -b <ringbuffer opt.> ... duration:NUM - switch to next file after NUM secs filesize:NUM - switch to next file after NUM KB files:NUM - ringbuffer: replace after NUM files RPCAP options: -A <user>:<password> use RPCAP password authentication Input file: -r <infile> set the filename to read from (no pipes or stdin!) Processing: -R <read filter> packet filter in Wireshark display filter syntax -n disable all name resolutions (def: all enabled) -N <name resolve flags> enable specific name resolution(s): "mnNtCd" --disable-protocol <proto_name> disable dissection of proto_name --enable-heuristic <short_name> enable dissection of heuristic protocol --disable-heuristic <short_name> disable dissection of heuristic protocol User interface: -C <config profile> start with specified configuration profile -Y <display filter> start with the given display filter -g <packet number> go to specified packet number after "-r" -J <jump filter> jump to the first packet matching the (display) filter -j search backwards for a matching packet after "-J" -m <font> set the font name used for most text -t a|ad|d|dd|e|r|u|ud output format of time stamps (def: r: rel. to first) -u s|hms output format of seconds (def: s: seconds) -X <key>:<value> eXtension options, see man page for details -z <statistics> show various statistics, see man page for details Output: -w <outfile|-> set the output filename (or '-' for stdout) Miscellaneous: -h display this help and exit -v display version info and exit -P <key>:<path> persconf:path - personal configuration files persdata:path - personal data files -o <name>:<value> ... override preference or recent setting -K <keytab> keytab file to use for kerberos decryption
We will examine each of the command line options in turn.
The first thing to notice is that issuing the command
wireshark by itself will
bring up Wireshark. However, you can include as many of the command line
parameters as you like. Their meanings are as follows ( in alphabetical order ):
Specify a criterion that specifies when Wireshark is to stop writing to a capture file. The criterion is of the form test:value, where test is one of:
If a maximum capture file size was specified, this option causes Wireshark to run in “ring buffer” mode, with the specified number of files. In “ring buffer” mode, Wireshark will write to several capture files. Their name is based on the number of the file and on the creation date and time.
When the first capture file fills up Wireshark will switch to writing to the next file, and so on. With the <command>files</command> option it’s also possible to form a “ring buffer.” This will fill up new files until the number of files specified, at which point the data in the first file will be discarded so a new file can be written.
If the optional <command>duration</command> is specified, Wireshark will also switch to the next file when the specified number of seconds has elapsed even if the current file is not completely fills up.
Print a list of the interfaces on which Wireshark can capture, then exit. For
each network interface, a number and an interface name, possibly followed by a
text description of the interface, is printed. The interface name or the number
can be supplied to the
-i flag to specify an interface on which to capture.
This can be useful on systems that don’t have a command to list them (e.g.,
Windows systems, or UNIX systems lacking
ifconfig -a). The number can be
especially useful on Windows, where the interface name is a GUID.
Note that “can capture” means that Wireshark was able to open that device to
do a live capture. If, on your system, a program doing a network capture must be
run from an account with special privileges (for example, as root), then, if
Wireshark is run with the
-D flag and is not run from such an account, it will
not list any interfaces.
-hoption requests Wireshark to print its version and usage instructions (as shown above) and exit.
Set the name of the network interface or pipe to use for live packet capture.
Network interface names should match one of the names listed in
(described above). A number, as reported by
wireshark -D, can also be used. If
you’re using UNIX,
netstat -i or
ifconfig -a might also work to list
interface names, although not all versions of UNIX support the
-a flag to
If no interface is specified, Wireshark searches the list of interfaces, choosing the first non-loopback interface if there are any non-loopback interfaces, and choosing the first loopback interface if there are no non-loopback interfaces; if there are no interfaces, Wireshark reports an error and doesn’t start the capture.
Pipe names should be either the name of a FIFO (named pipe) or “-” to read data from the standard input. Data read from pipes must be in standard libpcap format.
-rflag, jump to the first packet which matches the filter expression. The filter expression is in display filter format. If an exact match cannot be found the first packet afterwards is selected.
-Joption to search backwards for a first packet to go to.
-koption specifies that Wireshark should start capturing packets immediately. This option requires the use of the
-iparameter to specify the interface that packet capture will occur from.
mto enable MAC address resolution,
nto enable network address resolution, and
tto enable transport-layer port number resolution. This overrides
-nare present. The letter
Cenables concurrent (asynchronous) DNS lookups. The letter
denables resolution from captured DNS packets.
Sets a preference or recent value, overriding the default value and any value
read from a preference or recent file. The argument to the flag is a string of
the form prefname:value, where prefname is the name of the preference (which
is the same name that would appear in the
recent file), and
value is the value to which it should be set. Multiple instances of `-o
<preference settings> ` can be given on a single command line.
An example of setting a single preference would be:
wireshark -o mgcp.display_dissect_tree:TRUE
An example of setting multiple preferences would be:
wireshark -o mgcp.display_dissect_tree:TRUE -o mgcp.udp.callagent_port:2627
You can get a list of all available preference strings from the preferences file. See Appendix B, Files and Folders for details.
User access tables can be overridden using “uat,” followed by the UAT file name and a valid record for the file:
wireshark -o "uat:user_dlts:\"User 0 (DLT=147)\",\"http\",\"0\",\"\",\"0\",\"\""
The example above would dissect packets with a libpcap data link type 147 as HTTP, just as if you had configured it in the DLT_USER protocol preferences.
-pcannot be used to ensure that the only traffic that is captured is traffic sent to or from the machine on which Wireshark is running, broadcast traffic, and multicast traffic to addresses received by that machine.
Special path settings usually detected automatically. This is used for special cases, e.g. starting Wireshark from a known location on an USB stick.
The criterion is of the form key:path, where key is one of:
-coption. It must be used in conjunction with the
This option sets the format of packet timestamps that are displayed in the packet list window. The format can be one of:
-voption requests Wireshark to print out its version information and exit.
Specify an option to be passed to a TShark module. The eXtension option is in the form extension_key:value, where extension_key can be:
-X lua_script:my.lua, then
-X lua_script1:foowill pass the string foo to the my.lua script. If two scripts were loaded, such as
-X lua_script:other.luain that order, then a
-X lua_script2:barwould pass the string bar to the second lua script, namely other.lua.