To monitor how much traffic in total goes through an interface is easy with 
MRTG, provided the device supports SNMP.

However to monitor this split by source/destination IP address requires 
something called an RMAN probe, or similar.  Not may devices support this, and 
usually you need an extra device to do it.  This is because most 
routers/switches only count packets at the level below IP (I've forgotten my 
OSI model numbers...).  To count grouped by IP, they would need to do deeper 
packet inspection.  This is the same problem as when people ask to graph just 
the Web traffic on their network, which requires packet inspection down to the 
transport layer (TCP) to get the port number.

I've actually set up my home router to do exactly this, using the Linux 
firewall.  It counts internet traffic based on whose machine it is from/to, so 
I can hassle the appropriate teenager for using our data allocation...  This 
works because I have my wireless AP connected to the linux firewall, which then 
connects to the DSL, and the linux takes care of the NAT, DNS, DHCP, and 
firewall.  In your case it sounds as if your WRT54G is doing everything.  I 
also have a close relative of the WRT54G at my place, but I disabled the 
DNS,DHCP and DSL capabilities of it so as to use the Linux server for this 
instead (my DSL is not compatible with the WRT54G anyway)

In brief, I don't believe you can do what you want without additional more 
intelligent hardware, such as a linux firewall, or RMAN probe, or network 
sniffer.

Steve


________________________________
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Al Grant
Sent: Sunday, 3 August 2008 10:04
To: [email protected]
Subject: [mrtg] MRTG

Hi Folks,

A bit of a newbie here.

Could someone please tell me if I can monitor how much traffic is being used 
monthly by a IP on the LAN using DD-WRT and MRTG?

Thanks in advance,

-Al
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