Ubuntu/Debian installation command:
sudo apt-get install iftop
Example run with monitoring of all interfaces:
sudo iftop
An example of starting with monitoring the specified interface and packets accessing port 80:
sudo iftop -i eth0 -f "dst port 80"
I will give a list of possible launch options and describe them:
-h (help)
-n (do not display domain names instead of IP)
-N (do not associate port numbers with service names)
-p (start in promiscuous mode listening on all interfaces and packages)
-P (display ports)
-l (display IPv6 addresses)
-b (do not show traffic histograms)
-m limit (specifying the upper bandwidth limit in K, M, or G)
-B (display in bytes instead of bits)
-i interface (listen to packets only on the specified network interface)
-f filter (specifying special codes for filtering data)
-F net/mask (listen to packets of only the specified network, for example /24 or /255.255.255.0)
-G net6/mask6 (listen to packets of only the specified IPv6 network)
-c file (specifying a file with parameters)
-t (text mode)
Some function keys:
p (port mapping)
h (help)
q (exit)