@YeOldeStonecat:
Try the "BandwidthD" plugin.
"BandwidthD tracks usage of TCP/IP network subnets and builds html files with graphs to display utilization. Charts are built by individual IPs, and by default display utilization over 2 day, 8 day, 40 day, and 400 day periods. Furthermore, each ip address's utilization can be logged out at intervals of 3.3 minutes, 10 minutes, 1 hour or 12 hours in cdf format, or to a backend database server. HTTP, TCP, UDP, ICMP, VPN, and P2P traffic are color coded."
Wow! That's it! I forgot about packages… Though I installed nmap package before... :)
Thank you so much, sir! :) Would you like to point me, when I can see results of bandwidthd package job? I surfed through almost all menus and submenus and didn't find such a graphs (or I saw them but didn't understand this is bandwidthd's graphs... :)