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The Tiger and Leopard releases of MacOS X include an implementation of BSD’s dummynet. Dummynet is “a system facility that permits the control of traffic going through the various network interfaces“.

There are many uses for this feature. I use it as part of my website development to simulate a slow network connection. Many of the users of our websites are in developing countries with slow, dialup-speed, network connections. By using a couple of quick commands I can throttle my connection to the webserver down to similar speeds. As such, I can feel their pain even though I’m on a snazzy gigabit connection, two hops away from the webserver.

The following series of commands will slow my communications to and from the webserver down to 56K modem speeds. It only affects http connections (to any web server, not just mine). My other network connections – ssh, for example – operate with native network performance.

$ sudo ipfw add pipe 1 src-port http
$ sudo ipfw add pipe 1 dst-port http
$ sudo ipfw pipe 1 config bw 56kbit/s

Adam Knight’s Traffic Shaping in Mac OS X is a good starter tutorial.

Additional articles and documentation.


Wake the media, alert the dog. I installed Windows XP Pro into a Parallels virtual machine (VM) today.

Disabling ‘Acceleration’ in the VM was required for successful installation. With Acceleration enabled, the installation kept hanging at the “installing devices” stage (this could be progressed sometimes by forced restarting of the VM) and spontaneously rebooting.

From Problems with installing Windows XP SP0 in VM in Parallels’ knowledge base:

1. Change the acceleration mode of the VM:
2. Open the VM's configuration page. 
3. In the Resources list select Options.
4. Click the Advanced tab.
5. Set the Acceleration level to Normal or Disabled.
After installing Windows XP in the VM, you can change the Acceleration level back to High.

Things I learned in the past 24 hours.

1. If you use NetNewsWire 2.1 and one day it rejects your purchased serial number with “This serial number has been used too many times, or is associated with another NewsGator account.”, then you have hit a known bug and need to get the free update.

2. An account with NewsGator is required but not necessary to use NetNewsWire. A quandary that this harshes this consumer’s buzz.

Long winded rambling about NewsGator after the jump.

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January 2019
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