[PLUG] Red Hat routing follies

[Fedor Pikus]

I have a machine with 3 nics. The boot order only matters if you have them
compiled into the kernel (but then there are kernel parameters to force
the order), otherwise the one which is eth0 in modules.conf is eth0, and
so on. However, in addition to specifying GATEWAY you also specify
GATEWAYDEV=eth0 and this determines where the default route goes. Note
that the only thing this determines is the default route, of which you can
only have one. And, of course, you alsways get subnets routed throug their
respective interfaces (unless both are on the same subnet, then it's a
mess and you have to route by hand). After this, if you want to add some
other routes, you must do it explicitly.

On Sun, 26 Oct 2003, Carla Schroder wrote:

> Date: Sun, 26 Oct 2003 19:21:35 -0800
> From: Carla Schroder <carla at bratgrrl.com>
> Reply-To: plug at lists.pdxlinux.org
> To: plug at lists.pdxlinux.org
> Subject: [PLUG] Red Hat routing follies
>
> I have two NICs installed in one of my test boxes. Currently I'm messing
> around with Red Hat 9. The NICs are common DLink and Linksys, all duly
> recognized & drivers installed at installation. I'm using only one of them,
> the box connects to a gateway/firewall/switch unit. The IP of the gateway is
> 192.168.1.1
>
> The weird part is I can't figure out how Red Hat determines which one to use.
> They are configured the same:
>
> eth0
> DEVICE=eth0
> ONBOOT=yes
> BROADCAST=192.168.1.255
> IPADDR=192.168.1.6
> NETMASK=255.255.255.0
> GATEWAY=192.168.1.1
>
> eth1
> DEVICE=eth1
> ONBOOT=yes
> BROADCAST=192.168.1.255
> IPADDR=192.168.1.8
> NETMASK=255.255.255.0
> GATEWAY=192.168.1.1
>
>  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?
>
> This looks weird too:
>
> % /sbin/route
>
> Destination	Gateway	Genmask		Flags	Metric	Ref	Use	Iface
> 192.168.1.0		*	255.255.255.0	U		0		0	0	eth1
> 192.168.1.0		*	255.255.255.0	U		0		0	0	eth1
> 169.254.0.0		*	255.255.0.0	U		0		0	0	eth1
> 127.0.0.0			*	255.0.0.0		U		0		0	0	lo
> default				192.168.1.1	UG		0		0	0	eth1
>
> Wut the heck is going on here? How did eth1 get all the goodies? where did
> 169.254.0.0 come from?
>
> signed, dazed and confused
>

-- 
                                  Fedor G. Pikus
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