2. Using EtherApe

EtherApe can be used to have an overview of traffic conditions in your network. It is a great tool to easily pinpoint who is consuming the most bandwith, or to check which computers are actually talking to some others.

2.1. Quick Start

Most of the time you will want to run EtherApe with root permissions in order to monitor a live network. If you are not the administrator of the machine running EtherApe , you will ony be able to analyze previously generated capture files, generated by someone else.

Starting EtherApe opens the Main window, shown in Figure 1.

Figure 1. EtherApe Main Window

By default, EtherApe will try to open the default network interface for capture in IP mode, and will display a diagram of network traffic right away.

Every computer currently taking part in a conversation in the network will be represented as a circle (a node) in the diagram, with its name displayed on top of it. The fact that two computers are communicating with each other is represented with a line between those two nodes (a link).

You will notice that both nodes and links vary with time in color and size. Size is used to represent the amount of traffic: The bigger a node is, the more traffic it is dumping into the network. The wider a link is, the more data is flowing in that particular between those two nodes.

Color, on the other hand, is used to represent the protocol being used the most by a link or a node. You will find a legend for what a particular color means in the left side of the main window.

Look closely and you will notice that in fact links are not lines between nodes. Rather, every direction of communication is represented by a triangle. Packets go from the shorter side to the opposite vertex. Since computers usally talk back, there will usually be two such triangles between two nodes, the base of each representing how much each node is contributing to the conversation.

You don't need to know much more if you just want to have a simple look at your network. Nevertheless, there are many settings that you can use to configure what exactly will appear in the diagram, and you will have to understand how this settings affect the program to have a proper comprehension of the meaning of the display.

Besides, EtherApe offers you the possibility of displaying stastistics for many of the elements involved. Read on to learn how.

2.2. Toolbar

The toolbar (shown in Figure 2) provides access to several commonly used routines.

Figure 2. EtherApe Toolbar

Start

Starts the capture.

Pause

Freezes the display of both the main diagram and the additional information windows.

Stop

Finnishes the capture. The diagram, the protocol legend and the protocols window are cleared. Protocol and node information windows are deleted.

WarningWarning
 

Everytime a capture is stopped, all statistics gathered up to that time will be deleted from memory. Think about it when you have left EtherApe running for several hours.

2.3. Menus

The menu bar, located at the top of the Main Window, contains the following menus:

File

This menu contains:

  • Open (F3) — This opens a file which is saved on your computer.

  • Save (Ctrl-S) — This saves your file.

  • Close (Ctrl-W) — This closes your file.

  • Exit (Ctrl-Q) — This quits the application.

Edit

This menu contains:

  • Cut (Ctrl-X) — This removes any text or data which is selected and places it in the buffer.

  • Copy (Ctrl-C) — This copies any text or data which is selected into the buffer.

  • Paste (Ctrl-V) — This pastes any text or data which is copied into the buffer.

  • COMMAND1… — This opens the COMMAND1 dialog, which is used to ....

  • COMMAND2 — This ....

Settings

This menu contains:

  • Preferences… — This opens the Preferences Dialog, which allows you to configure many settings.

  • COMMAND3 — This command does something.

Help

This menu contains:

  • Manual — This opens the GNOME Help Browser and displays this manual.

  • About — This opens the About dialog which shows basic information about EtherApe, such as the author's name, the application version number, and the URL for the application's Web page if one exists.