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How to simulate slow internet connections on the mac

For testing purposes I would like to choke the performance of the network on my OS X 10.8.2 machine. I have currently Little Snitch installed, which I can block access to certain hosts with... however I would like to lower the network performance as if I would be using an 56k6 old-school modem.

How can I accomplish this?

  • 1
    Great wording - I'll point this to the canonical question we have on this tool and this will help guide everyone to the answers we have on Network Link conditioner.
    – bmike
    Nov 21, 2012 at 15:19
  • Thnx! Good idea. Nov 21, 2012 at 15:32

2 Answers 2


Although you can use command-line tools to do this, Apple has a developer tool that allows you to do what you are talking about from a control panel. There are presets available, or you can set your own performance limits. The tool is called "Network Link Conditioner" and is available on Apple's developer download site with a package called "Hardware IO Tools for Xcode".

Here is a blog post discussing the tool (with screen shots): http://mattgemmell.com/2011/07/25/network-link-conditioner-in-lion/

  • I just found about that. Thanks. The link, however, is developer.apple.com/downloads/… Nov 21, 2012 at 13:07
  • +1 for the link to the article - feel free to add that to the existing answers on the main thread for this. It's a very good article.
    – bmike
    Nov 21, 2012 at 15:38

After some more searching and talking with a friend of mine, I found the Hardware I/O tools for XCode which has the Network Link Conditioner which does this kind of things.


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