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The man page for ifdown roughly states (depending on the source of the man page):

The ifup and ifdown commands may be used to configure (or, respectively deconfigure) network interfaces based on interface definitions in ...

I'm not clear if the interface is "administratively" down or if its "powered" down.

My first question is, does ifdown power down the interface so that its not drawing any power?

My second question is, if the interface still receiving power, then how can I remove power from the interface?

I suspect the answer to the first question is going to be "maybe", and the second question is "it depends" based on the the chip and the driver. But I'd like feedback from those more experienced. Also note that physically removing an interface is not an option because it is soldered to the board.

  • I guess I'll say something better than "it depends": I will argue that most distros today moved away from ifup/ifdown because these scripts turned to be different on different distros. In essence ifup/ifdown are inconsistent across distros. Almost all distros moved to iproute2 and ifup/ifdown are just scripts that call ip/ifconfig. In the case of ifdown it is either: ip link <interface> down or ifconfig <interface> down, depending on distro. – grochmal Aug 6 '16 at 1:10
  • I can say that my board used to be an ill-fated buggy, and cheap realtek wifi chipset, with no shielding, and after I cut it physically, the wifi conditions at home improved. No, ifdown/not configuring it did not power it off. – Rui F Ribeiro Aug 6 '16 at 3:03
  • @RuiFRibeiro - The device is a Raspberry Pi 3. Its suffering intermittent lockups/freezes. I've replaced the power wart since it seems to be the number one cause, but others have suggested the problem is with the radios. I've thought about cutting the pins to the chips since I don't use the radios. – user56041 Aug 6 '16 at 5:51
  • Actually the device in question is also a rpi compatible board, however the wifi is(was) really bad. Not so familiar with the wifi of rpi3, I own one but it has not gave me the same amount of problems than the wifi of the Lamobo R1. – Rui F Ribeiro Aug 6 '16 at 13:18
  • Your question is incomplete. As others mentioned this can be system-specific. On my NetBSD system, ifconfig has an option for powersave, but on my Ubuntu system, I couldn't find anything that looked like the right thing. – MAP Aug 7 '16 at 23:22
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When wlan0 is up and connected, the power consumption of Raspberry Pi3 is around 300mA (at 5 volts). After running ifdown the power consumption reduces to 260mA. So this means the transceiver is off. Also scanning for nearby access points fails in this mode.

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