My normal response for this type of problem is to turn to Process Monitor, a free SysInternals?utility from Microsoft. The problem is that it’s a pretty geeky tool, and requires a little patience and understanding to get useful results.
Of late, I’ve found myself firing up a completely different utility included?in Windows 7 and 8 to monitor network activity. It’s a utility that quickly displays a lot of information about what’s going on. It?actually can monitor several areas of your computer’s activity, but I’ll focus?here on networking.
Perfmon
Perfmon, the system performance monitor, has been around for a long time. If?you run “perfmon” (Windows Key + “R”, enter “perfmon”, click OK) you’ll end up?with something similar to this.
It’s a fairly intimidating application, unless you’re well-versed in Windows?technical details, so it’s decidedly not what I’m recommending?here.
However.
In the descriptive text in the upper pane, you’ll see a link that says “Open?Resource Monitor”. Click that – it’s the tool that we want.
Resource Monitor
Resource Monitor is really just a process monitor with a different interface.?In fact, if instead of running “perfmon”, you run “perfmon /res” (without?the quotes), you come directly to this interface.
Resource Monitor is probably somewhere between Task Manager and our old?friend Process Explorer in?complexity, with just a hint of Process Monitor thrown in. (Yes, all?these similar sounding names can be quite confusing.)
As I said, I’m going to focus on using Resource Monitor to?monitor network activity.
Click on the Network tab.
Here you’ll find several panes of information about the network activity?happening on your machine.
Let’s review the three most interesting.
Network Activity Graph
At the top of the right-hand column, you’ll see this graph, which shows the average network?traffic total for the last 60 seconds.
Be forewarned?that the?scale will change automatically based on traffic. In the example?above, the scale is 10mbps, or 10 megabits per second, and?the graph peaks?at around the 4mbps range. If the traffic slows for long enough, the scale will?change to 100kbps, or even 10kbps, so that even at lower traffic rates, the?spikes of traffic can be viewed. It’ll also scale higher should network traffic?exceed 10mbps long enough. The important thing to realize is that you need to?pay attention to the scale to understand how much data is being?transferred.
Processes with Network Activity
This pane lists the processes that are actively doing some kind of network?I/O (input/output). The column headers can be clicked to sort by their contents, and I find?sorting by Total to be the most interesting. In the example above, we can see?that chrome.exe – the Google Chrome browser – was performing the most networked?I/O on the system when the snapshot was taken, followed by Dropbox, and?Thunderbird and others.
Network Activity
I find this perhaps the most useful network pane. Listed here are the?processes that have network activity, and remote endpoints to which they?are connected. Not shown above (but off to the right) are the same?Send/Receive/Total bytes columns, so you can see which connection is generating the most traffic.
In the example above, the most active connection is to an IP address: 67.201.31.35. A little?research shows that this IP address belongs to “NETDNA”, the content?distribution network that I use for Ask Leo! Indeed, I was downloading an?Ask Leo! page with images to generate example traffic.
You can see additional connections to “cotendo.net”, another content?distribution network, “1e100.net”, which turns out to be Google (I have Google?sites open in my browser, and the example page that I used to generate traffic?includes Google services), and “lw3.pugetsoundsoftware.com”, which is the server?currently housing Ask Leo!
TCP connections
This pane lists all of the TCP network connections that have been established?by applications running on your PC, whether or not they are actively?transmitting or receiving data. This can be useful to examine what programs are?connecting where out on the internet.
TCP Connections Graph
This graph shows the number of connections being made between your machine?and others across the network, over time. Like the Network Activity graph, it?also auto-scales, so do watch the maximum number shown to get a sense for?exactly what the graph is showing you.
Summary
Resource Monitor’s network monitoring pane provides a very quick and?informative window to monitor network activity happening on your machine. While it won’t tell you what files are being downloaded (you’ll still need Process Monitor for that – see the related links), it will tell you?what remote sites your computer is?connected to, and which of the?applications on your machine are responsible for network traffic. Those two?bits of information alone can often resolve many of the questions that you might?have about what’s happening on your machine.