ntop is a network probe that shows network usage in a way similar to 
what top does for processes. In interactive mode, it displays the 
network status on the user's terminal. In Web mode, it acts as a Web 
server, creating an HTML dump of the network status. 

It sports a NetFlow/sFlow emitter/collector, an HTTP-based client 
interface for creating ntop-centric monitoring applications, and 
RRD for persistently storing traffic statistics.

ntop requires rrdtool, which is also available at Slackbuilds.org.

ntop needs to run under its own user/group. This has been assigned to
the following by SlackBuilds.org, but feel free to change it on your
system for consistency with local assignments.
  User:   ntop            UID: 212        GID: 212
  group:  ntop                            GID: 212

If you want to change that, you'll need to change the script and 
the rc.ntop to reflect your changes.

Logs are placed in /var/log/ntop/ and will be rotated every week. The
log rotation will restart the ntop server which will reset the ntop
statistics. If you want to keep the statistics you have to edit or delete
the /etc/logrotate.d/ntop file.

If you want to start ntop on system bootup:

/etc/rc.d/rc.local
==================
    # Startup ntop
    if [ -x /etc/rc.d/rc.ntop ]; then
        /etc/rc.d/rc.ntop start
    fi

/etc/rc.d/rc.local_shutdown
===========================
    # Stop ntop
    if [ -x /etc/rc.d/rc.ntop ]; then
        /etc/rc.d/rc.ntop stop
    fi

Additionally, you'll have to set the rc script to be executable just
like any other Slackware rc script.
    # chmod +x /etc/rc.d/rc.ntop

When ntop is installed at the first time, you MUST set the 
administration password for ntop (user 'admin'). You do that 
by running ntop with the option -A (or --set-admin-password) as root.
    # /usr/bin/ntop -P <ntop_homedirectory> -u <ntopuser> -A
  For example:
    # /usr/bin/ntop -P /var/lib/ntop -u ntop -A
It will prompt you for the password and then exit. 

Running ntop:
Once ntop has started and configured correctly, you should be able to look 
at all the data it's collected by pointing your browser at:
    http://localhost:3000/
