Bandwidth usage monitoring tools

[Aeryn <aeryn_sunn hotmail com>]

Hello all, I was wondering if anybody knows of a good, open source bandwidth
usage monitoring tool for linux.   My problem is that I have a dedicated
webserver at a hosting company and they measure the bandwidth usage with
some networking tools.  Lately, their measurements are rather high for my
usage, at least it seems to me.  I need something I can use on my server
that will measure the amount of bandwidth usage I have for the server so
that I can have some idea if the hosting company's tools are measuring my
usage correctly.  If anybody has any ideas, please let me know.

Thanks,
A