[plug] Not even remotely local

[Leon Brooks]

Ginning around with a small home LAN last night, I came across a most unusual 
behaviour on an XP box: it had elected to set its loopback device to `obtain 
an IP address automatically.' Mmmm. _That's_ going to work... it eventually 
allocates itself an address in the 169.254.xxx.yyy range.

Because it's not a local address, the machine publishes it in the course of 
negotiating with its neighbours, which makes some scripting I'm doing with 
Samba noticeably harder because `nmblookup "*"' lists this rouge address 
(actually a private B-class subnet allocated by Microsoft specifically for 
when DHCP fails) along with all of the real ones.

Now comes the good part. If you visit the network configuration dialog and set 
the loopback interface to use a static address, XP barfs when you finish 
typing in `127.' because the address is reserved, and can I please choose a 
different one?

No worries, let's delete the interface and re-create it. Oh, look, the menu 
entry's grayed out. GAME OVER PLAYER<1>.

The same machine had a second network card, and until we physically removed 
this card (disabling it wasn't good enough), XP constantly wanted to `Bridge' 
it and the main card. `Bridging' here is not quite what the rest of the world 
means by `bridging;' rather than seamlessly forwarding traffic between 
interfaces, it means that the two cards are treated as one (this is often 
called `Bonding') and configured as one.

It also means that the machine doesn't respond to broadcasts, so doesn't 
appear when you do the nmblookup thing. Heaven help you should you happen 
have a non-functional built-in card and a functional plug-in card (as another 
mate from this circle of friends does).

Anyway, the Linux gateway there now has an additional `grep -v ^169\\.254\\.' 
link in the processing chain, and the DNS has an additional zonefile for 
254.169.in-addr.arpa that contains a single RR:

    *               IN      PTR     windows.xp.sucks.and.cannot.be.fuxed.

No, that's not a typoe.

Cheers; Leon