It can be very helpful to see a protocol in the way that the application layer sees it. Perhaps you are looking for passwords in a Telnet stream, or you are trying to make sense of a data stream. Maybe you just need a display filter to show only the packets in a TLS or SSL stream. If so, Wireshark’s ability to follow protocol streams will be useful to you.
To filter to a particular stream, select a TCP, UDP, DCCP, TLS, HTTP, HTTP/2 or QUIC packet in the packet list of the stream/connection you are interested in and then select the menu item Figure 7.1, “The “Follow TCP Stream” dialog box”.→ (or use the context menu in the packet list). Wireshark will set an appropriate display filter and display a dialog box with the data from the stream laid out, as shown in
Following a protocol stream applies a display filter which selects all the packets in the current stream. Some people open the “Follow TCP Stream” dialog and immediately close it as a quick way to isolate a particular stream. Closing the dialog with the “Back” button will reset the display filter if this behavior is not desired.
The stream content is displayed in the same sequence as it appeared on the network. Non-printable characters are replaced by dots. Traffic from the client to the server is colored red, while traffic from the server to the client is colored blue. These colors can be changed by opening→ and under → , selecting different colors for the and options.
The stream content won’t be updated while doing a live capture. To get the latest content you’ll have to reopen the dialog.
You can choose from the following actions:
By default, Wireshark displays both client and server data. You can select theto switch between both, client to server, or server to client data.
You can choose to view the data in one of the following formats:
You can switch between streams using the “Stream” selector.
You can search for text by entering it in the “Find” entry box and pressing.
The HTTP/2 Stream dialog is similar to the "Follow TCP Stream" dialog, except
for an additional "Substream" dialog field. HTTP/2 Streams are identified by
a HTTP/2 Stream Index (field name
http2.streamid) which are unique within a
TCP connection. The “Stream” selector determines the TCP connection whereas the
“Substream” selector is used to pick the HTTP/2 Stream ID.
The QUIC protocol is similar, the first number selects the UDP stream index while the "Substream" field selects the QUIC Stream ID.