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Archive for the ‘Networking’ Category

Automatically reset your cable modem when the Internet goes missing

So…  I have Comcast cable Internet service at home, and a Motorola SB6120 cable modem that I own myself.  I’m not sure if it is Comcast, the modem, the combination of the two, or something else altogether… but, every now and then, the modem goes into a funk and the Internet stops working, and the only way to fix it is to power-cycle the modem.

This doesn’t happen terribly often, maybe once a month or so.  (Occasionally it will happen, say, twice in one week and thus cause me to think about it a little more.)  Power-cycling the modem is not a big deal, but I do access stuff that I have at home remotely, so if the connection dies while I am at work or away someplace, I can’t fix it until I return home.

It would be great if there was a way for a computer at the house to, say, periodically check and see if the Internet is working and if it is not, somehow reset the modem.  So, I did some searching on the topic, and… it turns out that it is possible to do this, and in fact, it is pretty simple.

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WDS and WPA with Apple Airport Extreme

Apple Airport Extreme (and Express) wireless base stations support WPA encryption, and also WDS, which allows you to use multiple access points to create one big wireless network (so you don’t actually have to connect each access point to the same “backbone” network, as they will create wireless links between each other).

In this day and age, you’d be silly to use anything less than WPA encryption (WEP is fundamentally flawed), but there are a few caveats with setting up WPA and WDS together on Apple’s devices that I ran into while setting this up for someone recently.

  • WPA only works with Airport Express or Extreme access points. (It does not work with the original Airports, or the “snow” models.)
  • Upgrade your access points to the latest firmware, some earlier versions have a bug that prevents WPA and WDS from working together.
  • Your wireless network name (SSID) must be the same on all access points participating in WDS. (This doesn’t seem to be documented anywhere, and without WPA, you can use different SSIDs.)