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I am running Ubuntu 11.10 32bit Server on a single-board computer. I want the option of using the Ethernet interface (eth0) as a backend to control the computer if it's connected. I'm also lazy: if the cable is plugged in and I power the computer, I want eth0 up and running; in the event no cable is plugged in to eth0 upon powerup, I would like to be able to significantly reduce time it takes to bring eth0 `up' during boot.

I had thought that simply changing the DHCP timeout value to something small would do the job, but even after editing the /etc/dhcp/dhclient.conf, I still get the same long boot times when the cable is unplugged.

I understand the value of a robust bootup sequence for servers (see top answer for [1]), but I don't understand why changes to dhclient.conf are ignored during boot. Is there anything else going on under the hood that I'm not aware of? Perhaps I'm approaching the problem the wrong way (in which case I might need to ask a different question!)?

Thanks in advance for any input.

My /etc/network/interfaces file contains:

auto lo
iface lo inet loopback

auto eth0
iface eth0 inet dhcp

auto wlan0
iface wlan0 inet static
...

My /etc/dhcp/dhclient.conf file has uncommented and changed the line:

timeout 5;

[1] "Waiting for network configuration" adding 3 to 5 minutes to boot time

Community
  • 1
Jeffrey Wildman
  • 161

1 Answers1

1

Why are you using auto instead of allow-hotplug? If you use allow-hotplug and your hardware supports link detection, then your system will not even try doing DHCP if there is no link detected.

Another value you may want to look at changing is in the /etc/default/ifupdown file. Consider setting the IFUPDOWN_TIMEOUT timeout.

Zoredache
  • 298