3.2.4.3 Configuration
Using Ethereal can be as simple as you want it to be. By default it comes with
everything set up for full sniffing, and the only necessary setting is the selection of the
network interface device. However, because of a very user-friendly user interface, this
option is simple to use and easy to find.
To start sniffing, ensure that you have a network card in operational mode. This
means the NIC’s drivers must be installed and the card must be able to receive and
transmit data. If the card does not work properly before using Ethereal, it will certainly
not work while it is running. In addition, if you are using a WNIC, you might be limited
as to how far out on the network you can sniff. If you are using a *nix OS, you will
probably be able to sniff to at least the wireless router, wireless access point, or closest
switch. If you are using Windows, your WNIC will only capture local data. Keep this in
mind, or else you will spend hours attempting to troubleshoot a known issue.
To set up Ethereal to use your NIC, click Capture
→
Start. You will be shown a
screen similar to Figure 9.2.
