I’m keeping this short and sweet…
iftop isn’t in the CentOS repo by default which is a shame, luckily there is an rpm on repoforge available; just run this little bash command/script to install the correct version depending on arch or display saying it’s unavailable.
if uname -a | grep -q "64"; then rpm -ivh http://pkgs.repoforge.org/iftop/iftop-0.17-1.el6.rf.x86_64.rpm; elif uname -a | grep -q "86"; then rpm -ivh http://pkgs.repoforge.org/iftop/iftop-0.17-1.el6.rf.i686.rpm; else echo Not available for your arch.; fi
This should work on Fedora and Red Hat too.