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I am having internet problems and the ISP technicians suggested that something is using my bandwidth.

Is there a software to monitor which processes use how much bandwidth?

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    Hi there - Can I ask that you also describe what your internet problems are - the assumption that the ISP tech support guy is right may be a red herring to get you off the phone ;)
    – stuffe
    Nov 8, 2011 at 14:49
  • Internet became very slow. But not always. He did a test where I was connected not to the internet but only to the ISP, and the speed test was fine.
    – nute
    Nov 8, 2011 at 15:11
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    Put Activity Monitor in your dock, and set the dock icon to "Show Network Usage"… that won't show you which application is using it, but it will alert you to when it is happening, which might be of some help.
    – TJ Luoma
    Nov 9, 2011 at 9:17
  • Does this answer your question? Bandwidth shaper or bandwidth controller application for Mac OS X
    – bobobobo
    Apr 18 at 2:11

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I believe that Rubbernet is exactly what you are looking for.

The only downside is that Rubbernet cannot distinguish between LAN traffic and WAN traffic. It sounds like you are looking at one computer, so that shouldn't be an issue.

There is a demo available on their website, or you can buy it from the Mac App Store for US$25, which seems to be a pretty good deal since they want € 29.99 (about US$42) for a single user copy or € 49.99 (almost $69) for a "family pack" if you buy through their website.

(Hat tip to Macworld.com for bringing it to my attention a few months ago.)

If you want something cheaper, NetUse Traffic Monitor might suit you too.

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Built-in Activity Monitor (Applications → Utilities) shows you network usage. Also you can see open network ports for each running process.

screenshot

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    Activity monitor only seems to display sums over some period of time (the timespan isn't obvious). I wish it would show instantaneous usage (Mbps) of each app.
    – OzzieOrca
    Oct 19, 2018 at 4:28
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    Took me a while to realise that I should click the PACKETS label above the graph at the bottom to switch to monitor data usage in Mb/s
    – Johan Franzén
    Mar 24, 2020 at 9:03
  • Is there a way to get this at top of screen (in menu bar) without external software?
    – stevec
    Sep 22, 2020 at 19:38
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You can try nettop(1) in the Terminal. It is pre-installed, and refreshes every few seconds to provide a dashboard of all open network connections with their usage. Better than lsof since it shows the usage data too.

$ nettop

Then hit 'd' and look for odd-looking entries or entries with consistently large traffic in the 'bytes in' or 'bytes out' column. The 'd' instructs nettop to only show differences in each screen refresh.

Practical usage notes:

If you don't recognize the process name, Google it.

If you don't want the process around, get the pid (the number next to the process name in nettop), and kill it with kill -9 <pid>. If that doesn't solve it, find out if you can uninstall the process.

If you're interested in what the process is transmitting over the network, use the client port number for that particular connection (e.g. '53133' from 10.0.0.1:53133->74.125.68.100:80) to run a tcpdump(1) to see the data in the packets being exchanged: sudo tcpdump -nnvvXSs 1514 port 53133

If you're interested in the destination the process is talking to, but the destination IP address doesn't have a reverse DNS hostname (like in the previous example), then try visiting that IP address in a web browser as https://IP, click the broken lock icon in the address bar, and view the certificate details to find out which domain is served there (*.google.com in this case). This won't work if SSL port 443 isn't open on the destination.

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Perhaps Little Snitch might fit your needs. It's a paid app though, so you can try it out using it's trial version.

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  • I have Little Snitch (paid for), but it only quickly shows some process list without really telling me if its just a ping or using 1MB of bandwidth - unless I'm not using it correctly
    – nute
    Nov 8, 2011 at 15:10
  • +1, this is an awesome program. To see what processes are using the network, from the Little Snitch menu choose "Show Network Monitor".
    – Josh
    Nov 8, 2011 at 15:24
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First, most ISPs can tell you how much bandwidth you're using. It sounds like you had a technician that either didn't know much or was just trying to shoo you away.

Second, the only way to steal bandwidth is if you have a wireless network that isn't properly secured. This means you'll need to monitor bandwidth from your wireless router, not your laptop/desktop.

If you do have a wireless router, I would just change the SSID and secure it with a new (hard to guess) password. That will immediately cut-off anyone that could be leaching off your network. It's very simple to do compared to trying to monitor your bandwidth usage.

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  • This is not a wireless setup, it's an old-school PPPoE. If the technician is correct, it would be from my own computer. He ran speed tests by disconnecting me from the rest of the internet and having only the ISP in the DNS resolver, and it worked good.
    – nute
    Nov 8, 2011 at 15:12
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If you're looking for a way to monitor your Internet usage as a whole, including all devices connected to it, you might want to check out PeakHour (Mac Appstore).

It uses SNMP or UPnP to talk to routers and computers that can given you a real-time and historical view of bandwidth consumption and activity. This lets you monitor usage of your Internet connection as a whole, not just the computer you're on - useful if you have a few devices on your network.

Knowing your exact network activity or activity over time can be very helpful for diagnosing ISP issues. You can also monitor individual devices (if they support SNMP) which can be good for tracking down excessive usage.

peakhourapp.com

enter image description here

Heads up: I'm the developer.

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OsTrack (Mac App Store) tracks how much memory, cpu, and bandwidth each process is using. It may not be accurate to a very specific degree, but it works, has a nice UI, and is free so I suggest you give it a try.

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  • sounds interesting from the description. Will give it a try now.
    – nute
    Nov 8, 2011 at 15:14
  • not sure i understand the metrics - it shows uTorrent using 6MB - that can't be, my connection is only 1.5Mbps ... and I'm downloading at 0.2KB/s
    – nute
    Nov 8, 2011 at 15:17
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This page list four options: http://mac.appstorm.net/roundups/internet-roundup/4-ways-to-monitor-bandwidth-usage-on-your-mac/

The best two seem to be Surplus Meter (free) and Net Monitor($10)

There may also be linux tools available but I am not familar with them.

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I would check what apps use the network or which are listening for connection with lsof -Pi command.

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If you already have little snitch, here's a tip which you can quickly check how much you've [recently] used. I have limited data on tethering, which I use when there is no wifi available. It is useful to keep an eye on whats going on in short periods.

OSX Server app also has network monitoring tools. It comes free with the apple developer program.

little snitch monitor

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