![]() ![]() There is often much more going on than “meet’s the eye”! Protocols as we progress through the course! For now, you should just be aware that Even though the only action you took was toĭownload a web page, there were evidently many other protocols running on yourĬomputer that are unseen by the user. Of packets displayed as well (see, e.g., the many different protocol types shown in Somewhere in the listing of packets captured. HTTP message exchanges with the web server should appear Messages exchanged between your computer and other network entities! The You now have live packet data that contains all protocol Simple one line of congratulations), stop Wireshark packet capture by selecting The Ethernet frames containing these HTTP messages (as well as all other frames passing through your Ethernet adapter) will be captured by Wireshark.Īfter your browser has displayed the intro page (it is a Messages with the server in order to download this page, as discussed in lecture 1. In order to display this page, yourīrowser will contact the HTTP server at and exchange HTTP While Wireshark is running, enter the URL: Īnd have that page displayed in your browser. Will use the HTTP protocol that we will study in detail in class to download content from a website. To do so, we’ll need to generate some network traffic. Let’s capture some interesting packets first. This window shows the packets being captured.īy selecting Capture pulldown menu and selecting Stop, you can stop packet capture. Once you begin packet capture, a window similar to that shown in Figure 3 will appear. Packet capture will now begin - Wireshark is nowĬapturing all packets being sent/received from/by your computer on the selected interface! Interface on which you want to begin packet capture (in the case, the any). You’ll see a list of the interfaces on your computer. The packet-contents window displays the entire contents of the captured frame, in both ASCII and hexadecimal format. Or received this packet are also provided. Finally, details about the highest-level protocol that sent TCP or UDP, TCP or UDP details will also be displayed, which can similarly beĮxpanded or minimized. IP datagram line in the packet details window. Minimized by clicking on the plus minus boxes to the left of the Ethernet frame or The amount of Ethernet and IP-layer detail displayed can be expanded or Sent/received over an Ethernet interface) and IP datagram that contains this Include information about the Ethernet frame (assuming the packet was Packet-listing window and click with the left mouse button.). Listing window, place the cursor over the packet’s one-line summary in the (highlighted) in the packet-listing window. The packet-header details window provides details about the packet selected I.e., the protocol that is the source or ultimate sink for this packet. Protocol type field lists the highest-level protocol that sent or received this packet, The packet listing canīe sorted according to any of these categories by clicking on a column name. Was captured, the packet’s source and destination addresses, the protocol type,Īnd protocol-specific information contained in the packet. Packet number contained in any protocol’s header), the time at which the packet The packet-listing window displays a one-line summary for each packetĬaptured, including the packet number (assigned by Wireshark this is not a The packet-header and packet-contents windows) The packet display filter field, into which a protocol name or other information can be entered in order to filter the information displayed in the packet-listing window (and hence The Capture menu allows you to begin packet capture. The File menu allows you to save captured packet data or open a file containing previously captured packet data, and exit the Wireshark application. Of interest to us now are the File and Capture menus. The command menus are standard pulldown menus. In Figure 1, the assumed physical media is an Ethernet, and so all upper-layer protocols are eventually encapsulated within an Ethernet frame.Ĭapturing all link-layer frames thus gives you all messages sent/received from/by all protocols and applications executing in your computer. Or IP all are eventually encapsulated in link-layer frames that are transmitted over physical media such as an Ethernet cable. Recall from the discussion from lecture 1 that messages exchanged by higher layer protocols such as HTTP, FTP, TCP, UDP, DNS, The packet capture library receives a copy of every link-layer frame that is sent from or received by your computer. The packet sniffer, shown within the dashed rectangle in Figure 1 is an addition to the usual software in your computer, and consists of two parts. At the right of Figure 1 are the protocols (in this case, Internet protocols)Īnd applications (such as a web browser or ftp client) that normally run on your computer. Figure 1 shows the structure of a packet sniffer. ![]()
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