Two things: anti-spam and per-process *network* I/O.

[David Rysdam]

On Wed, 26 Dec 2012 11:16:10 -0500, "Ken D'Ambrosio" <ken at jots.org> wrote:
> Per-process I/O accounting.  Every now and then, I see a system load 
> spike through the roof -- but disk I/O is okay, likewise CPU.  Which 
> really pretty much leaves network.  But I'm unaware of any tool that 
> spits out per-process network utilization statistics.  One *must* exist, 
> right?  Any pointers?

There's this neat little website out there[1] that has all these cool
command line tricks and little utilities. I liked their "all time
greats" so much I set up a cron job to download them monthly and mail
one a day to myself. Today I got:

    # Monitor bandwidth by pid                                                                                                                                  nethogs -p eth0  

nethogs is in the debian repository.

[1] http://www.commandlinefu.com/commands/browse