Re: route trouble with kernel

From: Valdis . Kletnieks
Date: Tue Jun 28 2005 - 09:11:00 EST


On Tue, 28 Jun 2005 20:57:04 +0800, cigarette Chan said:
> i add a route to the kernel
> eg: # route add -net XXX.XXX.XXX.XXX/24 gw XXX.XXX.XXX.XXX dev eth1
>
> but after i restart eth1
>
> #ifdown eth1
> #ifup eth1
>
> the route disappear,this make me a lot of troubles.i have several
> interfaces,and i have to
> re-add all of these routes...
>
> Is there any way or patches to make route work like iptables,after i
> restart the interface,
> rules are still there.

Your system should have a way of doing this in a callout during the ifup
and ifdown scripts. Under Fedora, ifup calls ifup-post, which calls
/sbin/ifup-local - you could add your routes there.

More importantly, routes are different from iptables. At worst, an iptable
rule has a dangling '-i ethX' match that will fail if the interface is down,
but that's a harmless because the packet isn't from that interface.

On the other hand, what is the kernel supposed to do with a route that
points to a down'ed ethX after you've done the ifdown, but before you've
done the ifup? It may as well clear routes to the down'ed interface....

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