When sharing internet in my Macbook, from a 3G USB pendrive to Wi-Fi, if the 3G connection falls, the natd process rises up in CPU usage.

Is this a real problem? Is it expected in some way?

There's a easy way to solve the hogging, using the menubar disconnect option, but sometimes it doesn't work and I have to unplug the USB modem.

My modem is a HUAWEI E226.

Hope you can help me.

  • Sadly - it looks like the modem is getting your CPU stuck in a loop processing packets after the disconnect. Although it could be a Mac bug, it's more likely something from the modem. I've gone to a MiFi card to avoid my mac from running NAT and being less secure since internet sharing pokes holes in the firewall. – bmike Jun 6 '11 at 16:55

natd should be runnng ... NAT means Network Address Translation, so it's basically translating (communicating) between the Modem and the Wifi Access Point to share your connection.

You can read more about it here, natd

So in short this needs to run to share your connection,

Hope this helps.


  • Hi, thanks for the apple link, I'll read into that. Although the question is about the cpu hogging that the process does. – dequin Apr 7 '11 at 19:32
  • 1
    The hogging means it has more work to do than the CPU can dispatch at a lower utilization level. NAT translates packets, so if you can change your network to have less NAT traffic, the CPU load will go down. If you can't or won't modify your network, then you can turn off internet sharing on your CPU and add a dedicated NAT device for routing that traffic and have your CPU to yourself without it being loaded down. – bmike Jun 6 '11 at 16:52

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