How to interpret wireshark capture manual#

The protocol hierarchy is often the starting point for further analyses, because here indications of unexpected traffic or errors come to light, such as unexpected protocols or unexpected data ratios of individual protocols. Overall, the protocol hierarchy technique is a scaleable way to get an overall view of a pcap file. A separate capture file can be saved from the filtered results. However, a deductive strategy can be used by filtering out logs that are not of interest directly from the log hierarchy view. Due to the hierarchical structure of the list, it is not possible to sort or reorder the logs. A context menu opens to filter or colour packets directly. For this purpose, the entry is marked with the right mouse button for further analysis. If unexpectedly high values are detected in the data entries, this traffic should be examined more closely. In addition to the protocol information, an administrator can view how high the protocol's share of the total traffic is, the exact number of packets or the bandwidth of a protocol. Both text and background colours can be customized. User-defined colour rules can be assigned to their own profile and saved, complete the system. These colour codes help an administrator to identify the packet types at a glance. By default for example, all UDP packets are marked in blue, standard TCP transfer in purple and HTTP in green. In addition to the filter functions, Wireshark has a customizable colour coding system. Applying filters more esoteric than the simplest display filters requires in-depth knowledge of Wireshark's filter syntax in order to consistently use filters to address one's research question. In this article, only the most important filters that Wireshark provides as an on-board tool are addressed.

How to interpret wireshark capture manual#

The Wireshark manual contains much more information about the filters integrated in Wireshark. Capture filters are not trivial in their application because they are more cryptic than display filters. That is, a syntax of byte offsets, hex values, and masks associated with true values to filter the data. Wireshark capture filters use the same syntax as tcpdump, the libpcap filters. In addition to the display filters described above, which reduce the packets displayed, filters can be applied the moment that traffic recording begins these are called capture filters, ensuring that network data is limited to the desired selection.

If the filter is invalid, the area is highlighted in red. To check if the selected filter is correct, the filter toolbar turns green. Here, predefined operators can be selected and linked. This dialogue box opens when the term 'Expression' is right-clicked in the filter toolbar. Initially, it is easier to use Wireshark's Expression Builder dialogue box to add an expression to the display filter. Condition 1 states that the source IP address of the packets must be 10.17.2.5 and condition 2 specifies that the protocol must be TCP and the destination port must be 80.Īny number of conditions can be linked to further limit the selection of traffic displayed.Īs a skilled Wireshark user, expressions can be applied freely from memory. In this example, the conditions are linked with 'and'. Wireshark's filter syntax provides for parentheses, logical operators such as 'and' 'or', and comparison operators such as = or !=.įor example, if you want to show 'any TCP traffic from IP address 10.17.2.5 to port 80', the translation to Wireshark's filter syntax is ip.src = 10.17.2.5 and tcp.dstport = 80. In addition to using simple filters, conditions can also be linked.