Can Ethereal capture on (my T1/E1 line, SS7 links, etc.)?
Ethereal can only capture on devices supported by libpcap/WinPcap. On most OSes, only devices that can act as network interfaces of the type that support IP are supported as capture devices for libpcap/WinPcap, although the device doesn’t necessarily have to be running as an IP interface in order to support traffic capture. On Linux and FreeBSD, libpcap 0.8 and later support the API for Endace Measurement Systems’ DAG cards, so that a system with one of those cards, and its driver and libraries, installed can capture traffic with those cards with libpcap-based applications. You would either have to have a version of Ethereal built with that version of libpcap, or a dynamically-linked version of Ethereal and a shared libpcap library with DAG support, in order to do so with Ethereal. You should ask Endace whether that could be used to capture traffic on, for example, your T1/E1 link. See the SS7 capture setup page on the Ethereal Wiki for current information on capturing SS7 traffic on T
