#!/bin/bash

interface="$1"

direction="src" ipfield="12"
[[ "$2" == "down" ]] && direction="dst" ipfield="10"

myaddress="$(ifconfig "$interface"| sed -nr 's/.*inet addr:([0-9.]*) .*/\1/p')"

tcpdump -eni "$interface" "$direction" "$myaddress" |
  awk -v "ipfield=$ipfield" '
    {
      total[gensub(".[0-9]*:*$","",1,$ipfield)] += $9
      if (NR % 200 == 0) {
        for (i in total) {
          print total[i], i | "sort -nr|head -n 25"
        }
        print ""
        close ("sort -nr|head -n 25")
      }
    }'