yum -y install ncurses-devel libpcap-devel
cd /usr/local/src/
wget http://www.ex-parrot.com/~pdw/iftop/download/iftop-0.17.tar.gz
tar xvfvz iftop-*
cd iftop-*
./configure
make
make install
Referensi: http://xmodulo.com/2012/06/how-to-install-iftop-on-linux.html