   program to show network utilization on lan
  Can anyone give me a good free program to show how many bytes each client on a LAN is sending/receiving?  I have a good understanding of network setup and how networks work but i cant seem to find a good program.  I would prefer it to be rather simple and just give me a listing of each IP address and how many bytes they have sent/received.   
Process Monitor will show you each TCP send / recv which you can total up. There's also TCPView, but it's more of a glorified netstat.   ;  SNMP is one approach which should be available across all OSes. Simply find a client that suits you, but even if not, putting together a custom one shouldn't be too much of a problem.For Windows, performance counters might be another standard way.It also depends on platform, JVM for example exposes all performance metrics locally or remotely, and allows very high-grained tracking. I'm not immediately sure of any generic solution which would actually report data at per-socket resolution. SysInterals tools are mostly for local interactive use, but not really useful for bulk data acquisition.There are obviously complete solutions that allow comprehensive monitoring, but they tend to be focused on enterprise-grade networks (price/features).IMHO, for any kind of non-trivial measurements, poll all data and dump it into a database. Then it's trivial to either analyze it verbatim, or to push it through some suitable tools such as R.   ;  The problem is that most smart/learning switches will not forward non-broadcast packets to ports that have not had the MAC address in the packet visible in a previous packet. Thus, even if your interface is in promiscuous mode, you won't see all the traffic on a LAN from a single node.In general, if you want a good view, you want a managed switch (the high-end switches for $1,000, not the cheap crap for $50), which will keep statistics on a per-port basis, and make those statistics available; generally using SNMP.If your network has more switches and/or routers, then you'd need each of them to be managed to gather data for the whole network, and then aggregate it. There exists software that does this, both pay-for and free -- but one of the reasons businesses pay a lot more for infrastructure and management than homes is exactly this kind of management and reporting capability (which is necessary for capacity planning, etc).   