Linux Traffic/Bandwidth monitoring

[Gareth Harper]

Recently my bytemark vm has started to be utilised more than it has in 
the past (which is good).  Unfortunately the traffic monitoring tools on 
the bytemark website have been removed and I'd like to monitor how much 
throughput and traffic my machine is/has been utilising.  I've taken a 
look at ntop and a few other packages which seem to be a little 
heavyweight for my liking (memory intensive and not providing quite what 
I want).

I'd ideally like to be able to graph throughput (kb/sec) over a 
configurable timeframe (say in 5 minute intervals), and also Kb used 
over a configurable timeframe.  (so the two graphs would be KB/sec over 
time and KB over time). 

Does anyone know of any packages which allow this, or am I just going to 
have to bite the bullet and roll my own using iptables.

Gareth