ifto[ Installation Tutorial
Direct omit the above steps
CentOS system:
yum install flex byacc libpcap ncurses ncurses-devel
wget ftp://fr2.rpmfind.net/linux/dag/redhat/el5/en/i386/dag/RPMS/iftop-0.17-1.el5.rf.i386.rpm
rpm -ivh iftop-0.17-1.el5.rf.i386.rpm