There are many alternatives to Ethereal for Linux and since it's discontinued a lot of people are looking for a replacement. The best Linux alternative is Wireshark, which is both free and Open Source. If that doesn't suit you, our users have ranked more than 10 alternatives to Ethereal and four of them are available for Linux so hopefully you can find a suitable replacement. Other interesting Linux alternatives to Ethereal are tcpdump (Free, Open Source), netcat (Free, Open Source) and Ettercap (Free, Open Source).
Wireshark is the world's foremost network protocol analyzer. It lets you capture and interactively browse the traffic running on a computer network. It is the de facto (and often de jure) standard across many industries and educational institutions.
tcpdump is a common packet analyzer that runs under the command line. It allows the user to intercept and display TCP/IP and other packets being transmitted or received over a network to which the computer is attached.
Netcat is a featured networking utility which reads and writes data across network connections, using the TCP/IP protocol. It is designed to be a reliable "back-end" tool that can be used directly or easily driven by other programs and scripts.