"Pktstat" software shows an up-to-date record of active connections and their bandwidth consumption on a network interface. It provides real-time insight into the network traffic without requiring extra configuration.
One of the things I like about this program is that the entries hang around on the screen for a few seconds, so you can see what just happened. You can also use filter expressions similar to those in tcpdump. I find pktstat especially helpful when trying to identify what is clogging up my modem.
Requirements for using pktstat include having libpcap 0.5 installed on your computer. In the latest release, the packet and octet counter ranges have been increased from 32 bit to 64 bit, and window resize event handling has been improved. The new version also fixes a buffer overflow bug and adds a single-shot batch output mode.
Version 1.8.4: N/A