wireshark-filter(4)
NAME
wireshark-filter - Wireshark filter syntax and reference
SYNOPSIS
wireshark [other options] [ -R "filter expression" ] tshark [other options] [ -R "filter expression" ]
DESCRIPTION
Wireshark and TShark share a powerful filter engine that helps remove the noise from a packet trace and lets you see only the packets that interest you. If a packet meets the requirements expressed in your filter, then it is displayed in the list of packets. Display filters let you compare the fields within a protocol against a specific value, compare fields against fields, and check the existence of specified fields or protocols. Filters are also used by other features such as statistics generation and packet list colorization (the latter is only available to Wireshark). This manual page describes their syntax. A comprehensive reference of filter fields can be found within Wireshark and in the display filter reference at <https://www.wireshark.org/docs/dfref/>.
FILTER SYNTAX
Check whether a field or protocol exists
The simplest filter allows you to check for the existence of a protocol
or field. If you want to see all packets which contain the IP
protocol, the filter would be "ip" (without the quotation marks). To
see all packets that contain a Token-Ring RIF field, use "tr.rif".
Think of a protocol or field in a filter as implicitly having the
"exists" operator.
Comparison operators
Fields can also be compared against values. The comparison operators
can be expressed either through English-like abbreviations or through
C-like symbols:
eq, == Equal
ne, != Not Equal
gt, > Greater Than
lt, < Less Than
ge, >= Greater than or Equal to
le, <= Less than or Equal to
Search and match operators
Additional operators exist expressed only in English, not C-like
syntax:
contains Does the protocol, field or slice contain a value
matches Does the protocol or text string match the given Perl
regular expression
The "contains" operator allows a filter to search for a sequence of
characters, expressed as a string (quoted or unquoted), or bytes,
expressed as a byte array. For example, to search for a given HTTP URL
in a capture, the following filter can be used:
http contains "https://www.wireshark.org"
The "contains" operator cannot be used on atomic fields, such as
numbers or IP addresses.
The "matches" operator allows a filter to apply to a specified Perl-
compatible regular expression (PCRE). The "matches" operator is only
implemented for protocols and for protocol fields with a text string
representation. For example, to search for a given WAP WSP User-Agent,
you can write:
wsp.user_agent matches "(?i)cldc"
This example shows an interesting PCRE feature: pattern match options
have to be specified with the (?option) construct. For instance, (?i)
performs a case-insensitive pattern match. More information on PCRE can
be found in the pcrepattern(3) man page (Perl Regular Expressions are
explained in <http://perldoc.perl.org/perlre.html>).
Functions
The filter language has the following functions:
upper(string-field) - converts a string field to uppercase
lower(string-field) - converts a string field to lowercase
upper() and lower() are useful for performing case-insensitive string
comparisons. For example:
upper(ncp.nds_stream_name) contains "MACRO"
lower(mount.dump.hostname) == "angel"
Protocol field types
Each protocol field is typed. The types are:
ASN.1 object identifier
Boolean
Character string
Compiled Perl-Compatible Regular Expression (GRegex) object
Date and time
Ethernet or other MAC address
EUI64 address
Floating point (double-precision)
Floating point (single-precision)
Frame number
Globally Unique Identifier
IPv4 address
IPv6 address
IPX network number
Label
Protocol
Sequence of bytes
Signed integer, 1, 2, 3, 4, or 8 bytes
Time offset
Unsigned integer, 1, 2, 3, 4, or 8 bytes
An integer may be expressed in decimal, octal, or hexadecimal notation.
The following three display filters are equivalent:
frame.pkt_len > 10
frame.pkt_len > 012
frame.pkt_len > 0xa
Boolean values are either true or false. In a display filter
expression testing the value of a Boolean field, "true" is expressed as
1 or any other non-zero value, and "false" is expressed as zero. For
example, a token-ring packet's source route field is Boolean. To find
any source-routed packets, a display filter would be:
tr.sr == 1
Non source-routed packets can be found with:
tr.sr == 0
Ethernet addresses and byte arrays are represented by hex digits. The
hex digits may be separated by colons, periods, or hyphens:
eth.dst eq ff:ff:ff:ff:ff:ff
aim.data == 0.1.0.d
fddi.src == aa-aa-aa-aa-aa-aa
echo.data == 7a
IPv4 addresses can be represented in either dotted decimal notation or
by using the hostname:
ip.dst eq www.mit.edu
ip.src == 192.168.1.1
IPv4 addresses can be compared with the same logical relations as
numbers: eq, ne, gt, ge, lt, and le. The IPv4 address is stored in
host order, so you do not have to worry about the endianness of an IPv4
address when using it in a display filter.
Classless InterDomain Routing (CIDR) notation can be used to test if an
IPv4 address is in a certain subnet. For example, this display filter
will find all packets in the 129.111 Class-B network:
ip.addr == 129.111.0.0/16
Remember, the number after the slash represents the number of bits used
to represent the network. CIDR notation can also be used with
hostnames, as in this example of finding IP addresses on the same Class
C network as 'sneezy':
ip.addr eq sneezy/24
The CIDR notation can only be used on IP addresses or hostnames, not in
variable names. So, a display filter like "ip.src/24 == ip.dst/24" is
not valid (yet).
IPX networks are represented by unsigned 32-bit integers. Most likely
you will be using hexadecimal when testing IPX network values:
ipx.src.net == 0xc0a82c00
Strings are enclosed in double quotes:
http.request.method == "POST"
Inside double quotes, you may use a backslash to embed a double quote
or an arbitrary byte represented in either octal or hexadecimal.
browser.comment == "An embedded \" double-quote"
Use of hexadecimal to look for "HEAD":
http.request.method == "\x48EAD"
Use of octal to look for "HEAD":
http.request.method == "\110EAD"
This means that you must escape backslashes with backslashes inside
double quotes.
smb.path contains "\\\\SERVER\\SHARE"
looks for \\SERVER\SHARE in "smb.path".
The slice operator
You can take a slice of a field if the field is a text string or a byte
array. For example, you can filter on the vendor portion of an
ethernet address (the first three bytes) like this:
eth.src[0:3] == 00:00:83
Another example is:
http.content_type[0:4] == "text"
You can use the slice operator on a protocol name, too. The "frame"
protocol can be useful, encompassing all the data captured by Wireshark
or TShark.
token[0:5] ne 0.0.0.1.1
llc[0] eq aa
frame[100-199] contains "wireshark"
The following syntax governs slices:
[i:j] i = start_offset, j = length
[i-j] i = start_offset, j = end_offset, inclusive.
[i] i = start_offset, length = 1
[:j] start_offset = 0, length = j
[i:] start_offset = i, end_offset = end_of_field
Offsets can be negative, in which case they indicate the offset from
the end of the field. The last byte of the field is at offset -1, the
last but one byte is at offset -2, and so on. Here's how to check the
last four bytes of a frame:
frame[-4:4] == 0.1.2.3
or
frame[-4:] == 0.1.2.3
A slice is always compared against either a string or a byte sequence.
As a special case, when the slice is only 1 byte wide, you can compare
it against a hex integer that 0xff or less (which means it fits inside
one byte). This is not allowed for byte sequences greater than one
byte, because then one would need to specify the endianness of the
multi-byte integer. Also, this is not allowed for decimal numbers,
since they would be confused with hex numbers that are already allowed
as byte strings. Neverthelss, single-byte hex integers can be
convienent:
frame[4] == 0xff
Slices can be combined. You can concatenate them using the comma
operator:
ftp[1,3-5,9:] == 01:03:04:05:09:0a:0b
This concatenates offset 1, offsets 3-5, and offset 9 to the end of the
ftp data.
The membership operator
A field may be checked for matches against a set of values simply with
the membership operator. For instance, you may find traffic on common
HTTP/HTTPS ports with the following filter:
tcp.port in {80 443 8080}
as opposed to the more verbose:
tcp.port == 80 or tcp.port == 443 or tcp.port == 8080
Type conversions
If a field is a text string or a byte array, it can be expressed in
whichever way is most convenient.
So, for instance, the following filters are equivalent:
http.request.method == "GET"
http.request.method == 47.45.54
A range can also be expressed in either way:
frame[60:2] gt 50.51
frame[60:2] gt "PQ"
Bit field operations
It is also possible to define tests with bit field operations.
Currently the following bit field operation is supported:
bitwise_and, & Bitwise AND
The bitwise AND operation allows testing to see if one or more bits are
set. Bitwise AND operates on integer protocol fields and slices.
When testing for TCP SYN packets, you can write:
tcp.flags & 0x02
That expression will match all packets that contain a "tcp.flags" field
with the 0x02 bit, i.e. the SYN bit, set.
Similarly, filtering for all WSP GET and extended GET methods is
achieved with:
wsp.pdu_type & 0x40
When using slices, the bit mask must be specified as a byte string, and
it must have the same number of bytes as the slice itself, as in:
ip[42:2] & 40:ff
Logical expressions
Tests can be combined using logical expressions. These too are
expressible in C-like syntax or with English-like abbreviations:
and, && Logical AND
or, || Logical OR
not, ! Logical NOT
Expressions can be grouped by parentheses as well. The following are
all valid display filter expressions:
tcp.port == 80 and ip.src == 192.168.2.1
not llc
http and frame[100-199] contains "wireshark"
(ipx.src.net == 0xbad && ipx.src.node == 0.0.0.0.0.1) || ip
Remember that whenever a protocol or field name occurs in an
expression, the "exists" operator is implicitly called. The "exists"
operator has the highest priority. This means that the first filter
expression must be read as "show me the packets for which tcp.port
exists and equals 80, and ip.src exists and equals 192.168.2.1". The
second filter expression means "show me the packets where not (llc
exists)", or in other words "where llc does not exist" and hence will
match all packets that do not contain the llc protocol. The third
filter expression includes the constraint that offset 199 in the frame
exists, in other words the length of the frame is at least 200.
A special caveat must be given regarding fields that occur more than
once per packet. "ip.addr" occurs twice per IP packet, once for the
source address, and once for the destination address. Likewise,
"tr.rif.ring" fields can occur more than once per packet. The
following two expressions are not equivalent:
ip.addr ne 192.168.4.1
not ip.addr eq 192.168.4.1
The first filter says "show me packets where an ip.addr exists that
does not equal 192.168.4.1". That is, as long as one ip.addr in the
packet does not equal 192.168.4.1, the packet passes the display
filter. The other ip.addr could equal 192.168.4.1 and the packet would
still be displayed. The second filter says "don't show me any packets
that have an ip.addr field equal to 192.168.4.1". If one ip.addr is
192.168.4.1, the packet does not pass. If neither ip.addr field is
192.168.4.1, then the packet is displayed.
It is easy to think of the 'ne' and 'eq' operators as having an
implicit "exists" modifier when dealing with multiply-recurring fields.
"ip.addr ne 192.168.4.1" can be thought of as "there exists an ip.addr
that does not equal 192.168.4.1". "not ip.addr eq 192.168.4.1" can be
thought of as "there does not exist an ip.addr equal to 192.168.4.1".
Be careful with multiply-recurring fields; they can be confusing.
Care must also be taken when using the display filter to remove noise
from the packet trace. If, for example, you want to filter out all IP
multicast packets to address 224.1.2.3, then using:
ip.dst ne 224.1.2.3
may be too restrictive. Filtering with "ip.dst" selects only those IP
packets that satisfy the rule. Any other packets, including all non-IP
packets, will not be displayed. To display the non-IP packets as well,
you can use one of the following two expressions:
not ip or ip.dst ne 224.1.2.3
not ip.addr eq 224.1.2.3
The first filter uses "not ip" to include all non-IP packets and then
lets "ip.dst ne 224.1.2.3" filter out the unwanted IP packets. The
second filter has already been explained above where filtering with
multiply occurring fields was discussed.
FILTER FIELD REFERENCE
The entire list of display filters is too large to list here. You can
can find references and examples at the following locations:
* The online Display Filter Reference:
<https://www.wireshark.org/docs/dfref/>
* Help:Supported Protocols in Wireshark
* "tshark -G fields" on the command line
* The Wireshark wiki: <https://wiki.wireshark.org/DisplayFilters>
NOTES
The wireshark-filters manpage is part of the Wireshark distribution. The latest version of Wireshark can be found at <https://www.wireshark.org>. Regular expressions in the "matches" operator are provided by GRegex in GLib. See <http://developer.gnome.org/glib/2.32/glib-regex-syntax.html/> or <http://www.pcre.org/> for more information. This manpage does not describe the capture filter syntax, which is different. See the manual page of pcap-filter(7) or, if that doesn't exist, tcpdump(8), or, if that doesn't exist, <https://wiki.wireshark.org/CaptureFilters> for a description of capture filters.
SEE ALSO
wireshark(1), tshark(1), editcap(1), pcap(3), pcap-filter(7) or tcpdump(8) if it doesn't exist.
AUTHORS
See the list of authors in the Wireshark man page for a list of authors of that code.
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