Wireshark provides a simple but powerful display filter language that allows you
to build quite complex filter expressions. You can compare
values in packets as well as combine expressions into more
specific expressions. The following sections provide more
information on doing this.
Every field in the packet details pane can be used as a filter
string, this will result in showing only the packets where this field
exists. For example: the
filter string: tcp will show all packets containing the
There is a complete list of all filter fields available
through the menu item "Help/Supported Protocols" in the page "Display Filter
Fields" of the Supported Protocols dialog.
XXX - add some more info here and a link to the statusbar info.
You can express integers in decimal, octal, or
hexadecimal. The following display filters are
ip.len le 1500
ip.len le 02734
ip.len le 0x436
Signed integer (8-bit, 16-bit, 24-bit, 32-bit)
A boolean field is present in the protocol decode
only if its value is true. For example,
tcp.flags.syn is present, and
thus true, only if the SYN flag is present in a
TCP segment header.
Thus the filter expression
tcp.flags.syn will select only
those packets for which this flag exists, that is,
TCP segments where the segment header contains the
SYN flag. Similarly, to find source-routed token
ring packets, use a filter expression of
Ethernet address (6 bytes)
Separators can be a colon
(:), dot (.) or dash (-) and can have one or
two bytes between separators:
Wireshark allows you to string together single ranges
in a comma separated list to form compound ranges as
6.4.4. A common mistake
Using the != operator on combined expressions like: eth.addr, ip.addr,
tcp.port, udp.port and alike will probably not work as expected!
Often people use a filter string to display something like
ip.addr == 188.8.131.52 which will display all packets
containing the IP address 184.108.40.206.
Then they use ip.addr != 220.127.116.11 to see all packets
not containing the IP address 18.104.22.168 in it. Unfortunately, this does
not do the expected.
Instead, that expression will even be true for packets where either
source or destination IP address equals 22.214.171.124. The reason for this,
is that the expression ip.addr != 126.96.36.199 must be read as "the
packet contains a field named ip.addr with a value
different from 188.8.131.52". As an IP datagram contains both a source and
a destination address, the expression will evaluate to true whenever
at least one of the two addresses differs from 184.108.40.206.
If you want to
filter out all packets containing IP datagrams to or from IP address
220.127.116.11, then the correct filter is !(ip.addr == 18.104.22.168) as it
reads "show me all the packets for which it is not true
that a field named ip.addr exists with a value of 22.214.171.124", or in
other words, "filter out all packets for which there are
no occurrences of a field named ip.addr with the value 126.96.36.199".