OT: Network bandwidth monitor

[Roberto Ragusa]

Steve Repo wrote:
> Hello,
> 
> I have a network of  20 hosts and all of them are windows machines
> except one Fedora 10 box. One of the machines is using all the
> bandwidth and seem to be uploading  something.  We have a liberal
> network policy and policing the firewall is beyond my hands.
> 
> What i'd like to do  is identify this rogue machine that is uploading
> something and using our bandwidth.  I thought I could identify the box
> that is using up the most network bandwidth.  Oh, we all machines are
> on DHCP.
> 
> Should I install iftop and run it on the fedora box?  or do i have to
> make fedora as the router to capture all traffic? Any other tools that
> does bandwidth monitoring?

Excuse me if what I'm going to say sounds too stupid, but...
could you have a look at the LEDs behind the machines?
could you have a look at the LEDs on your network switch?
could you unplug each machine for a few seconds and see if
the traffic slows down?

Because it is not easy to observe the traffic on your Fedora box;
if the network is switched you have to rearrange things
so the traffic actually goes to the Fedora box, as you
already noted yourself.

If the used bandwidth is really huge, the involved machine
could be slower in responding to pings.
Try pinging them all and see if one of them is remarkably slower.
You can ping them one by one or all together (option -b).

-- 
   Roberto Ragusa    mail at robertoragusa.it