Is there any way to force my Linux box to always boot up with a self-assigned IP address?

Question

This is perhaps an unusual request: I'm trying to get a Debian Linux box to always give itself a self-assigned IP address (i.e. 169.254.x.y) on boot. In particular, I want it to do that even when there is a DHCP server present on the LAN. That is, it should not request an IP address from the DHCP server.

From what I can see in the "man interfaces" text, there is an option for "manual", and an option for "dhcp". Manual assignment won't do, since I need multiple boxes to work on the same LAN without requiring any manual configuration... and "dhcp" does what I want, but only if there is no DHCP server on the LAN. (A requirement is that the functionality of these boxes should not be affected by the presence or absence of a DHCP server).

Is there a trick that I can use to get this behavior?

EDIT: By "no manual configuration", I mean that I should be able to take this box (headless) to any LAN anywhere, plug in the Ethernet cable, and have it do its thing. I shouldn't have to ssh to the box and edit files to get it working each time it is moved to a different LAN.

Answer 1

If you install the avahi-autoipd package, and run it with the --force-bind option in a custom init or if-up.d script, you will always get a link-local address.

You can then use iface eth0 inet manual in your interfaces(5) file, although you will need to edit /etc/network/if-up.d/avahi-autoipd to add manual to the method lines.

There is more information about avahi-autoipd on the Avahi wiki.

Personally, I would edit /etc/network/if-up.d/avahi-autoipd to with something like:

--- avahi-autoipd       2010-08-04 04:26:49.000000000 +0800
+++ avahi-autoipd.1     2010-11-11 09:57:54.000000000 +0800
@@ -13,10 +13,13 @@
 esac

 case "$METHOD" in
-       static|dhcp|NetworkManager) ;;
+       static|dhcp|NetworkManager|linklocal) ;;
        *) exit 0
 esac

+if [ "$METHOD" == "linklocal" ]; then
+       /usr/sbin/avahi-autoipd --force-bind --daemonize --wait $IFACE 2> /dev/null
+fi

 if [ -x /bin/ip ]; then
        # route already present?

You can then list interfaces as iface eth0 inet linklocal. The edits to be made to the if-down.d script are left as an exercise to the reader.

Answer 2

You may have missed this in man interfaces:

The ipv4ll Method
   This method uses avahi-autoipd to configure an interface with an IPv4 Link-Layer address
   (169.254.0.0/16  family). This method is also known as "APIPA" or "IPAC", and often col‐
   loquially referred to as "Zeroconf address".

   Options

          (No options)

So, you would have an interfaces section as such:

auto eth0
iface eth0 inet ipv4ll

Install avahi-autoipd, and that should do it.

Answer 3

I think what you are looking for is zeroconf.

Answer 4

Nobody's mentioned it yet, so I'll just point out that, if you have control of how the machine boots, you can edit the default entry in GRUB's menu.lst (or whatever it's called this week) to add a "nodhcp" cheatcode to the arguments given the kernel at boot. That should at least keep the machine from sending out an initial IP request, though for how long I couldn't say as I've only really needed it when testing live-CDs (it's all static RFC1918 IP's on my LAN).

Answer 5

Posting for the sake of others Googling for this:

If you are using NetworkManager, As of July 2008 it includes support for avahi-autoipd. Just set BOOTPROTO=autoip in the interface's /etc/sysconfig/network-scripts/ifcfg-* file. NetworkManager will skip DHCP configuration of the interface and go straight to link-local IPv4LL addressing via autoipd.