WIRESHARK-FILTER(4) WIRESHARK-FILTER(4)
NAME
wireshark-filter - Wireshark display filter syntax and reference
SYNOPSIS
wireshark [other options] [ -Y "display filter expression" |
--display-filter "display filter expression" ]
tshark [other options] [ -Y "display filter expression" |
--display-filter "display 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 .
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".
Whenever a protocol or field appears as the argument of a function in a
filter, an exists operator for that protocol or field implicitly
appears.
Values and operators
Each field has a value, and that value can be used in operations with
comparable values (which may be literals, other fields, or function
results). The value of a field is not necessarily what appears in the
Wireshark display or TShark output. For example, a protocol is
semantically equivalent to the sequence of bytes that it spans, not its
displayed text in the protocol tree.
Comparison operators
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
The ordering depends on the value type in the usual way (e.g.,
lexicographic for strings and arithmetic for integers.) A field may
appear more than once in a given frame. In that case equality can be
strict (all fields must match the condition) or not (any field must
match the condition). The inequality is the logical negation of
equality. The following table contains all equality operators, their
aliases and meaning:
eq, any_eq, == Any field must be equal
ne, all_ne, != All fields must be not equal
all_eq, === All fields must be equal
any_ne, !== Any fields must be not equal
The operators "any" or "all" can be used with any comparison operator
to make the test match any or all fields:
all tcp.port > 1024
any ip.addr != 1.1.1.1
The "any" and "all" modifiers take precedence over comparison operators
such as "===" and "any_eq".
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 string match the given case-insensitive
Perl-compatible regular expression
The "contains" operator allows a filter to search for a sequence of
characters, expressed as a string, or bytes, expressed as a byte array.
The type of the left hand side of the "contains" operator must be
comparable to that of the right hand side after any implicit or
explicit conversions.
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" or "~" operator allows a filter to apply to a specified
Perl-compatible regular expression (PCRE2). The regular expression
must be a double quoted string. The left hand side of the "matches"
operator must be a string, which can be a non-stringlike field
implicitly or explicitly converted to a string. Matches are
case-insensitive by default. For example, to search for a given WAP
WSP User-Agent, you can write:
wsp.header.user_agent matches "cldc"
This would match "cldc", "CLDC", "cLdC" or any other combination of
upper and lower case letters.
You can force case sensitivity using
wsp.header.user_agent matches "(?-i)cldc"
This is an example of PCRE2's (?option) construct. (?-i) performs a
case-sensitive pattern match but other options can be specified as
well. More information can be found in the
pcre2pattern(3)|https://www.pcre.org/current/doc/html/pcre2pattern.html
man page.
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
len(field) - returns the byte length of a string or bytes field
count(field) - returns the number of field occurrences in a frame
string(field) - converts a non-string field to string
max(f1,...,fn) - return the maximum value
min(f1,...,fn) - return the minimum value
abs(field) - return the absolute value of numeric fields
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"
string() converts a field value to a string, suitable for use with
operators like "matches" or "contains". Integer fields are converted to
their decimal representation. It can be used with IP/Ethernet
addresses (as well as others), but not with string or byte fields. For
example:
string(frame.number) matches "[13579]$"
gives you all the odd packets.
max() and min() take any number of arguments and returns one value,
respectively the largest/smallest. The arguments must all have the same
type.
Protocol field types
Each protocol field is typed. The types are:
ASN.1 object identifier, plain or relative
AX.25 address
Boolean
Byte sequence
Character string
Character, 1 byte
Date and time
Ethernet or other MAC address
EUI64 address
Fibre Channel WWN
Floating point, single or double precision
Frame number
Globally Unique Identifier
IEEE-11073 floating point, 16 or 32 bits
IPv4 address
IPv6 address
IPX network number
Label
OSI System-ID
Protocol
Signed integer, 1, 2, 3, 4, or 8 bytes
Time offset
Unsigned integer, 1, 2, 3, 4, or 8 bytes
VINES address
An integer may be expressed in decimal, octal, hexadecimal or binary
notation, or as a C-style character constant. The following seven
display filters are equivalent:
frame.len > 10
frame.len > 012
frame.len > 0xa
frame.len > 0b1010
frame.len > '\n'
frame.len > '\x0a'
frame.len > '\012'
Boolean values are either true or false. In a display filter
expression testing the value of a Boolean field, true is expressed as
the word true (case-insensitive) or any non-zero number. False is
expressed as false (case-insensitive) or the number zero. For example,
a token-ring packet's source route field is Boolean. To find any
source-routed packets, a display filter would be any of the following:
tr.sr == 1
tr.sr == true
tr.sr == TRUE
Non source-routed packets can be found with:
tr.sr == 0
tr.sr == false
tr.sr == FALSE
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.src == 192.168.1.1
ip.dst eq www.mit.edu
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 Inter-Domain 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 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
network as 'sneezy' (requires that 'sneezy' resolve to an IP address
for filter to be valid):
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).
Transaction and other IDs are often represented by unsigned 16 or 32
bit integers and formatted as a hexadecimal string with "0x" prefix:
(dhcp.id == 0xfe089c15) || (ip.id == 0x0373)
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". This may be more conveniently
written as
smb.path contains r"\\SERVER\SHARE"
String literals prefixed with 'r' are called "raw strings". Such
strings treat backslash as a literal character. Double quotes may still
be escaped with backslash but note that backslashes are always
preserved in the result.
The following table lists all escape sequences supported with strings
and character constants:
\' single quote
\" double quote
\\ backslash
\a audible bell
\b backspace
\f form feed
\n line feed
\r carriage return
\t horizontal tab
\v vertical tab
\NNN arbitrary octal value
\xNN arbitrary hexadecimal value
\uNNNN Unicode codepoint U+NNNN
\UNNNNNNNN Unicode codepoint U+NNNNNNNN
Date and time values can be given in ISO 8601 format or using a legacy
month-year-time format:
"2020-07-04T12:34:56"
"Sep 26, 2004 23:18:04.954975"
The 'T' separator in ISO 8601 can be omitted. The timezone can be given
as "Z" or an offset from UTC.
When not using ISO 8601 the timezone can be given as the strings "UTC",
"GMT" or "UT" for UTC or also given as an offset from UTC, plus some
North American and Nautical/Military designations (see the
specification for %z in strptime(3)
). Note that arbitrary timezone
names are not supported however.
If the timezone is omitted then date and time values are interpreted as
local time.
The slice operator
You can take a slice of a field if the field base type is a text string
or a byte array (the base type of most network address fields is
bytes). 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
Slice indexes are zero-based. 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
As mentioned above the slice operator can be used on string and byte
fields and will respectively produce string or byte slices. String
slices are indexed on UTF-8 codepoint boundaries (i.e:
internationalized characters), so the following comparison is true:
"touche"[5] == "e"
The example above generates an error because the compiler rejects
constant expressions but is otherwise syntactically correct and
exemplifies the behaviour of string slices.
To obtain a byte slice of the same string the raw (@) operator can be
used:
@"touche"[5-6] == c3:a9
A slice can always be compared against either a string or a byte
sequence.
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 layer operator
A field can be restricted to a certain layer in the protocol stack
using the layer operator (#), followed by a decimal number:
ip.addr#2 == 192.168.30.40
matches only the inner (second) layer in the packet. Layers use simple
stacking semantics and protocol layers are counted sequentially
starting from 1. For example, in a packet that contains two IPv4
headers, the outer (first) source address can be matched with
"ip.src#1" and the inner (second) source address can be matched with
"ip.src#2".
For more complicated ranges the same syntax used with slices is valid:
tcp.port#[2-4]
means layers number 2, 3 or 4 inclusive. The hash symbol is required to
distinguish a layer range from a slice.
The at operator
By prefixing the field name with an at sign (@) the comparison is done
against the raw packet data for the field.
A character string must be decoded from a source encoding during
dissection. If there are decoding errors the resulting string will
usually contain replacement characters:
browser.comment == "string is ����"
The at operator allows testing the raw undecoded data:
@browser.comment == 73:74:72:69:6e:67:20:69:73:20:aa:aa:aa:aa
The syntactical rules for a bytes field type apply to the second
example.
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
To find HTTP requests using the HEAD or GET methods:
http.request.method in {"HEAD", "GET"}
The set of values can also contain ranges:
tcp.port in {443, 4430..4434}
ip.addr in {10.0.0.5 .. 10.0.0.9, 192.168.1.1..192.168.1.9}
frame.time_delta in {10 .. 10.5}
Implicit type conversions
Fields which are sequences of bytes, including protocols, are
implicitly converted to strings for comparisons against (double quoted)
literal strings and raw strings.
So, for instance, the following filters are equivalent:
tcp.payload contains "GET"
tcp.payload contains 47.45.54
As noted above, a slice can also be compared in either way:
frame[60:2] gt 50.51
frame[60:2] gt "PQ"
The inverse does not occur; stringlike fields are not implicitly
converted to byte arrays. (Some operators allow stringlike fields to
be compared with unquoted literals, which are then treated as strings;
this is deprecated in general and specifically disallowed by the
"matches" operator. Literal strings should be double quoted for
clarity.)
A hex integer that is 0xff or less (which means it fits inside one
byte) can be implicitly converted to a byte string. This is not
allowed for hex integers 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 or octal numbers, since they would be confused
with the hex numbers that make up byte string literals. Nevertheless,
single-byte hex integers can be convenient:
frame[4] == 0xff
frame[1:4] contains 0x02
Bitwise operators
It is also possible to define tests with bitwise operations. Currently
the following bitwise operator is supported:
bitwise_and, & Bitwise AND
The bitwise AND operation allows masking bits and 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.
To match locally administered unicast ethernet addresses you can use:
eth.addr[0] & 0x0f == 2
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
Arithmetic operators
Arithmetic expressions are supported with the usual operators:
+ Addition
- Subtraction
* Multiplication
/ Division
% Modulo (integer remainder)
For example it is possible to filter for UDP destination ports greater
or equal by one to the source port with the expression:
udp.dstport >= udp.srcport + 1
It is possible to group arithmetic expressions using curly brackets
(parenthesis will not work for this):
tcp.dstport >= 4 * {tcp.srcport + 3}
Do not confuse this usage of curly brackets with set membership.
An unfortunate quirk in the filter syntax is that the subtraction
operator must be preceded by a space character, so "A-B" must be
written as "A -B" or "A - B".
Protocol field references
A variable using a sigil with the form ${some.proto.field} is called a
field reference. A field reference is a field value read from the
currently selected frame in the GUI. This is useful to build dynamic
filters such as, frames since the last five minutes to the selected
frame:
frame.time_relative >= ${frame.time_relative} - 300
Field references share a similar notation to macros but are distinct
syntactical elements in the filter language.
Logical expressions
Tests can be combined using logical expressions. These too are
expressible in C-like syntax or with English-like abbreviations. The
following table lists the logical operators from highest to lowest
precedence:
not, ! Logical NOT (right-associative)
and, && Logical AND (left-associative)
xor, ^^ Logical XOR (left-associative)
or, || Logical OR (left-associative)
The evaluation is always performed left to right. Expressions can be
grouped by parentheses as well. The expression "A and B or not C or D
and not E or F" is read:
(A and B) or (not C) or (D and (not E)) or F
It's usually better to be explicit about grouping using parenthesis.
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 exists
llc", 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.
Because each comparison has an implicit exists test for field values
care must 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. This is the same as writing:
ip.dst and ip.dst ne 224.1.2.3
The filter selects only frames that have the "ip.dst" field. Any other
frames, 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.dst or ip.dst ne 224.1.2.3
not ip.dst eq 224.1.2.3
The first filter uses "not ip.dst" 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 also negates the implicit existence test and so is a
shorter way to write the first.
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:
o The online Display Filter Reference:
o View:Internals:Supported Protocols in Wireshark
o tshark -G fields on the command line
o The Wireshark wiki:
NOTES
The wireshark-filter(4) manpage is part of the Wireshark distribution.
The latest version of Wireshark can be found at
.
Regular expressions in the "matches" operator are provided by the PCRE2
library. See 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,
for a
description of capture filters.
Display Filters are also described in the User's Guide:
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.
2024-04-06 WIRESHARK-FILTER(4)