[PLUG] Red Hat routing follies

[Aaron Burt]

On Sun, 26 Oct 2003, Carla Schroder wrote:

> I have two NICs installed in one of my test boxes. <snip>
>
> The weird part is I can't figure out how Red Hat determines which one to use.
> They are configured the same:
>
> DEVICE=eth0
> ONBOOT=yes
>
> DEVICE=eth1
> ONBOOT=yes

It uses both.  Set "ONBOOT=no" on any you're not using.

>  The first time I booted it up, I had eth1 connected. But I couldn't get a
> network connection until I moved the cable to eth0. Now RH has decided it
> will use eth1.  How?

Oy.  That sort of eenie-miney-moe stuff is not something I've been able to
explain, but static-IP ports come up whether there's a network there or
not.  Since they're both static, it brings up and routes both of 'em.

> This looks weird too:
>
> % /sbin/route
>
> Destination	[...]	Iface
> 192.168.1.0	[...]	eth1
> 192.168.1.0	[...]	eth1
> 169.254.0.0	[...]	eth1
> 127.0.0.0	[...]	lo
> default	[...]	eth1
>
> Wut the heck is going on here? How did eth1 get all the goodies?

They both route to the same network, and eth1 was the last one to come up,
I 'spect.  So it did the obvious [sic] thing and used the wrong one.

> where did 169.254.0.0 come from?

Your internet router, most likely.

> signed, dazed and confused

unsigned, but overflowed anyway,
  Aaron