I discover this tools when I play around in a Freebsd vmware image. You may not find it at your yum repo and also apt-get repo. But installation is easy, dependencies are less too. What you need are ncursors and libpcap, use yum search or apt-cache search to query and download the dependencies and download trafshow from here.
Installation is easy, login as root
./configure; make; make install
Once done, type
and it will allow you to select the interface to show, you can open multiple trafshow to monitor different interfaces. One thing I like about trafshow is it is clean and lively shows me the traffic events, where I usually put that as background, if something unusual happens I will be aware of it.
Trafshow allows you to do filter like tcpdump, for example I want trafshow display me only udp events with source IP is 192.168.1.2
trafshow udp and src 192.168.1.2
Press h when you are in trafshow, there have many instant options to play around.