I am sure this is simple, but Google is full of users which cannot get a DHCP address So no matter what search term I use, I only see solutions which do not apply to this problem.

I am running Debian Squeeze on a netbook eeePC 1001P I have a wireless interface and a wired interface defined in /etc/network/interfaces:

Both interfaces WORK! When I have plugged in a cable, eth0 acquires and gets an IP, when I am in reach of the WiFi, wlan0 gets an IP address.

Now when I want to use only wireless, and I have no LAN connected, this is what happens at boot:
This is fine, however it takes forever (I think 60 seconds) before DHCP decides to time out. That is awkward. This is my wife's computer and I cannot tell her to intervene manually when she is either in Wifi range or on the LAN.

Why is dhclient called when it is detected that eth0 is not ready? How can I disable acquiring a DHCP address on an interface which is not ready?

My idea is that when a link is not ready, acquiring a DHCP address is skipped. How can I configure that? I have looked thru the ifup scripts, but nothing. Where do I see what is happening when the interface is auto eth0?

jlinkels

No it isn't awkward. But maybe shorter timeout settings can be added to the dhclient configuration file.


Editing the script to include a little piece of code that checks device link state (mii-diag or whatever else available) before firing off dhclient else ifplugd or netplugd?

Well, if you have to wait for something while you are sure it is not gonna happen, the time is awkwardly long. Shortening the timeout in dhclient.conf I have tought about, but is not elegant. You don't want to make it too short so proper acquiring can take place, while on the other hand even 5 seconds timeout is long, bearing in mind that everything in the init process has been optimized to shave off tens of seconds.

Never heard of mii-diag, but it certainly looks promising. Thanks. And for ifplugd and netplugd, yes these seems to be the appropriate places but I had hoped for something so that I wouldn't have to re-invent the wheel.

jlinkels

Edit: I read through this: http://www.debian.org/doc/manuals/re...fplugd_package
before I posted this question. I must have been very tired not to recognize the solution offered here!

Well, it was easy and then again, not.

I found the information for what I wanted to do on this web site: http://www.howtoforge.com/whereami_i...fi_debian_etch

A few remarks on unexpected results or what was not fully clear from this web page.

- To detect wireless, the wlan detection in detect.conf:
worked best for me. Excluding the interface name defaults to eth0 for wireless which is not good. Excluding the essid but not the wep-key gave false positives.
- Even when wireless is detected, you might not be able to obtain a DHCP address on your laptop when the signal is too weak. When I was testing, my wireless quality was 23/70, but that was too low to obtain an address. Closer to the AP the wireless was working well. I didn't find a solution for that and left it that way.
- in the /etc/network/interfaces you must specify but you must not include as this brings up the interface and try to acquire a DHCP address at boot time.

jlinkels

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