My favorite Terminal Network monitoring tools

I would like to introduce some of my favorite network monitoring tools.

I will start with the 'simple as perfect' ifstat.
ifstat is "Report InterFace STATistics"
It lists all the network interfaces and displays the download and upload rates in a continuous stream. It can be scripted quite easily.

Similar to ifstat but with more options is bmon.
bmon is a "Portable bandwidth monitor and rate estimator"
It lists all the network interfaces and displays the current RX and TX rate.
It can show detailed statistics such as the errors, the total bytes the dropped packets etc.
Also it has a graphical statistics option.

Next on my list is iptraf.
iptraf is a "Interactive Colorful IP LAN Monitor"
It has a very nice text based menu and it can display lots of statistics about the interfaces.
It also has a IP traffic monitor showing the tcp and the udp connections.

Another powerful tool is iftop.
iftop can "display bandwidth usage on an interface by host"
and does exactly what is says. It displays the bandwidth usage of every host in a very nice graphical way.
This tool is very useful on a proxy server.

Last but not least, is ngrep and tcpdump.
Those tools are perfect for viewing and graping the network traffic.
They can be used with several filters.

For each one of the programs I described previously, there is a very nice man page you should try to read first before asking anything.

For graphical statistics collection tools, try ntop, munin and cacti. Each one suits different needs.