[Lisi <lisi.reisz@xxxxxxxxx>]

My question is, I'm afraid, very elementary, and possibly very dumb.  I am a 
complete newbie to Wireshark and to packet-sniffers in general.

How do you use a capture filter?  I.e., how do you turn it on and off?  How do 
you make it _do_ anything?

There is a menu item under capture for capture filters.  But selecting any of 
the filters doesn't seem to have any effect.

Thanks,
Lisi