Product Name : IFTOP
Product Version : 0.17
Homepage : http://www.ex-parrot.com/~pdw/iftop/
Description : ftop does for network usage what top(1) does for CPU usage. It listens to network traffic on a named interface and displays a table of current bandwidth usage by pairs of hosts. Handy for answering the question "why is our ADSL link so slow?".

Step 1: Installing libpcap

cd /usr/local/src
wget http://www.securecentos.com/files/src/libpcap-0.9.8.tar.gz
tar -zxvf libpcap-0.9.8.tar.gz
cd libpcap-0.9.8
./configure
make && make install

Step 2: Installing IFTOP

cd /usr/local/src
wget http://www.ex-parrot.com/~pdw/iftop/download/iftop-0.17.tar.gz
tar -zxvf iftop-0.17.tar.gz
cd iftop-0.17
./configure
make && make install

Step 3: Making IFTOP root only

chmod 700 /usr/local/sbin/iftop

Step 4: How to use IFTOP

Start it:

iftop -i eth0

Press H