When I was running Mandrake Linux I couldn't get (meaning, didn't know how at the time) to get the FVWM window manager to work as I wanted, so I used icewm. Actually, I might still use it, if I could figure out how to set up a giant virtual desktop like FVWM has.
But I digress. One of the things I liked about icewm is that it had a network traffic meter which fit into the toolbar. This was particularly helpful because it let me know when my Linksys BEFW11S4 (ver 4) router decided that it didn't want to handle downloading that file anymore, thank you very much.
FVWM doesn't come with a traffic meter, but a quick Google search found Roland's software for Linux. Roland created a program called xnetload. It was easy to compile, though I had to hand-change the install location from the default /usr/local to my preferred /home/local location.
And then I was able to get it into FVWM's ButtonBar. After much playing around, I finally decided on an entry that looked like this: *FvwmButtons(2x2, Frame 2, Title eth0, Swallow(UseOld) "xnetload" 'Exec xnetload -nv -ni -kb eth0 -fg red -bg gray &') which monitors my ethernet port ("eth0") displays the upload and download information in graphic form only ("-nv -ni"), and logs information in kilobytes.
So thank you Roland, great software.