Mr George

Topics: Ethernet, Transmission Control Protocol, Wireshark Pages: 5 (1438 words) Published: April 14, 2013
Wireshark (Ethereal) Tutorial
If you have not use Wireshark, this is the chance to learn this power networking tool, majority of all rest labs will be based on Wireshark.

Our Sun Workstation administrator is installing wireshark. Meanwhile, if you have a personal PC and Internet access, you can install wireshark onto your PC. You can find the free software at Http:// Once Wireshark is up, please follow instructions in the file Wireshark_tutorial. You don’t need submit anything, since it is to get familiar with the tool. If you have any question, please contact with Mini:, her office hour is Monday 11:30am – 1:30pm at Sun Workstation lab.

Running Wireshark
When you run the Wireshark program, the Wireshark graphical user interface shown in Figure 2 will de displayed. Initially, no data will be displayed in the various windows. command menus display filter specification listing of captured packets

details of selected packet header

packet content in hexadecimal and ASCII Figure 2: Wireshark Graphical User Interface

The Wireshark interface has five major components: The command menus are standard pulldown menus located at the top of the window. Of interest to us now are the File and Capture menus. The File menu allows you to save captured packet data or open a file containing previously captured packet data, and exit the Wireshark application. The Capture menu allows you to begin packet capture.

The packet-listing window displays a one-line summary for each packet captured, including the packet number (assigned by Wireshark; this is not a packet number contained in any protocol’s header), the time at which the packet was captured, the packet’s source and destination addresses, the protocol type, and protocol-specific information contained in the packet. The packet listing can be sorted according to any of these categories by clicking on a column name. The protocol type field lists the highest level protocol that sent or received this packet, i.e., the protocol that is the source or ultimate sink for this packet. The packet-header details window provides details about the packet selected (highlighted) in the packet listing window. (To select a packet in the packet listing window, place the cursor over the packet’s one-line summary in the packet listing window and click with the left mouse button.). These details include information about the Ethernet frame (assuming the packet was sent/receiverd over an Ethernet interface) and IP datagram that contains this packet. The amount of Ethernet and IP-layer detail displayed can be expanded or minimized by clicking on the plus-or-minus boxes to the left of the Ethernet frame or IP datagram line in the packet details window. If the packet has been carried over TCP or UDP, TCP or UDP details will also be displayed, which can similarly be expanded or minimized. Finally, details about the highest level protocol that sent or received this packet are also provided. The packet-contents window displays the entire contents of the captured frame, in both ASCII and hexadecimal format. Towards the top of the Wireshark graphical user interface, is 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 packet-header and packet-contents windows). In the example below, we’ll use the packet-display filter field to have Wireshark hide (not display) packets except those that correspond to HTTP messages.

Taking Wireshark for a Test Run
The best way to learn about any new piece of software is to try it out! We’ll assume that your computer is connected to the Internet via a wired Ethernet interface. Do the following 1. Start up your favorite web browser, which will display your selected homepage. 2. Start up the Wireshark software. You will initially see a window similar to that shown in Figure 2, except that no packet data...
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