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Question

I need to slow down (simulate bad) internet connection, I found some documentation where it was achieved by "ipfw pipe" command , the thing is that in latest MAC OS versions , ipfw was deprecated (and removed)...

I was wondering if there are any alternative to the ipfw API ? Does anyone know how latest Network Link Conditioner achieves it?

The original previous way which enabled to slow down an internet connection :

sudo ipfw pipe 1 config bw 56Kbit/s delay 200 plr 0.2

and to clear the pipe :

sudo ipfw delete 1

Thanks.

Answer

I don't know much about Mac OS (I use Linux myself), but I'll give this a shot.

A bunch of digging established that ipfw seems unavailable, as you say.

I was also unable to find a way to use the Network Link Conditioner from the command line. Everything should be usable from the command line, so that's stupid.

One work around would be to try to access the NLC from within AppleScript. The following will get you started on toggling the NLC:

property thePane : "com.apple.Network-Link-Conditioner"  
tell application "System Preferences"  
activate  
  set the current pane to pane id thePane  
--delay 2  
end tell  
---  
tell application "System Events"  
  tell application process "System Preferences"  
  try  
  click ((checkboxes of window "Network Link Conditioner") whose description is "enable switch")  
  on error  
  click ((checkboxes of window "Network Link Conditioner") whose description is "enable switch")  
  end try  
  end tell  
end tell  

I think that you can run a script from the terminal with osascript <SCRIPT>.

As an alternative, Charles Proxy is a pay-to-use program that can be used to perform throttling, provided you can convince the software you are testing to connect to the proxy's port rather than directly to the internet. Maybe there are free proxy solutions out there somewhere?

Perhaps Squid would work in that regard. SquidMan seems to be an easy-ish way to install it for Mac. It looks as though DelayPools and or Client Bandwidth Limits might be useful for simulating a low speed connection, though I can't find evidence of people having used them for such.