Re: [LARTC] ip routing problems in 2.4.20

[Ard van Breemen <ard@kwaak.net>]

On Mon, May 05, 2003 at 01:21:52PM +0200, ulrich schwarz wrote:
> Ard van Breemen wrote:
> >Hi,
> >Has anybody noticed that when:
> >ip addr add 192.168.0.1/32 dev eth0
> >ip route add 192.168.0.2/32 dev eth0
> 
> /32? this would be a subnetmask with one host per subnet - so how could 
> the host communicate with a router in it's own subnet? not at all.

The use of whatever ip address to bind an interface to the ip
stack should not have any consequences to the arp behaviour if
rp_filter=0. If I said:
ip addr add 127.0.0.1/32 dev eth0
ip link set up eth0
echo 0 > /proc/sys/net/ipv4/conf/eth0/rp_filter

it should answer any arp request for any of it's ip addresses.
Adding a route to a device only makes sure that you can make
rp_filter=1.
At least that used to be the behaviour before 2.4.20. I've tested
a lot of this stuff, and it is used in a lot of places (not only
by me). It would hurt a lot of people if it does not work any
more.

> it seems to me this doesn't make much sense. maybe i just haven't got 
> the point.

Split a /24 in a lot of smaller subnets on a firewall with > 50
interfaces.

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