networking,software-rec,monitoring,bandwidth – Best Network Monitoring Tools

something to get you started (just in case you want to write it yourself):

#!/bin/bash
#
# usage: bwmon PID

IN=0; OUT=0; TIME=0

get_traffic() {
    t=`awk '/eth0:/ { printf("%s,%d,%d\n",strftime("%s"),$2,$10); }' < /proc/$1/net/dev`
    IN=${t#*,}; IN=${IN%,*}
    OUT=${t##*,};
    TIME=${t%%,*};
}

get_traffic $1
while true
do
    _IN=$IN; _OUT=$OUT; _TIME=$TIME
    get_traffic $1
    echo "$TIME,$(( $TIME - $_TIME )),$IN,$(( $IN - $_IN )),$OUT,$(( $OUT - $_OUT))"
    sleep 1
done

comments:

• checks only eth0
• checks every 1 second
• works only under linux, but other unixes work similar (procfs or whatever)
• output could be stored into a sqlite.db with stat --printf="%N\n" /proc/PID/exe | cut -d ' ' -f 3

There are a lot of answers. I personally use Zenoss, but there's a big list here: http://en.wikipedia.org/wiki/Comparison_of_network_monitoring_systems