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Cerin
Asked: 2016-10-10 16:50:55 +0800 CST

How to disable ethernet check during boot

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I have Ubuntu 16 running on a Raspberry Pi 3 mobile platform, and if it's not connected to ethernet, and the wifi's out of range during boot, it takes about 15 minutes to boot, since it appears Ubuntu has a very long timeout while it waits to bring up eth0 or wlan0. I've tested this repeatedly, and when the boot takes forever, I find plugging in an ethernet cable magically makes boot completely instantly.

How do I disable this, so Ubuntu boots up quickly, regardless of network connectivity? I'm using Network Manager, which is excellent at re-establishing a wlan0 connection onces an recognized SSID is detected.

boot

3 Answers

  1. Fire up your favorite text editor: /etc/systemd/system/network-online.targets.wants/networking.service

    Find and edit this line with your meat fidgets: TimeoutStartSec=5min

    ?

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  2. The problem is that eth0 was hardcoded in /etc/network/interfaces, so networking always tried to bring it up at boot.

    Since I'm using Network Manager, I found the easiest solution was to remove all the eth0 entries from /etc/network/interfaces. This makes Network Manager auto-detect it and bring it up if present.

    Edit: Even with the eth0 entry removed the /etc/network/interfaces, booting was still slow (even though it was faster than before). I found adding the entry back, but changing it from "auto" to "manual" made boot happen almost instantly.

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  3. The sleep commands waiting for the network can be changed in the file

    /etc/init/failsafe.conf
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