Re: Where do packets sent to 255.255.255.255 go?

Wei-Che, Hsu
2005-09-19T07:44:04Z

Dear sir,

I have the same question recently & found a solution on the following url.
http://www.uwsg.iu.edu/hypermail/linux/kernel/0508.3/0397.html
& trace to this mailing list.

I had added a 255.255.255.255 route to a specific interface(eth0).
But seems no luck.
The broadcast package still go out via default gateway(eth1).
(detail "route -n" will be attached on the tail of this mail.)

Does anyone have any idea about it?
Should I enable something on my kernel?

ThanX in advance.

=== Original Post ===
>>> 3. Can I set the default broadcast interface explicitly?
>>> For example, say I wanted broadcasts to go out over
>>> eth1 by default, instead of over eth0. What if I
>>> wanted them to get sent through tap0?
>>
>> Again, I'm not sure, but I think that you can force the
>> interface by adding a special route for IP 255.255.255.255
>> and with mask 255.255.255.255 to the interface you want.

> Yes, this works! It's so simple --- I can't believe I
> didn't try it before. I did mess around with iptables,
> trying to add some weird PREROUTEing DNAT that would
> redirect the packets, but I didn't know what I was doing.
=== Original Post ===

=== Detail route output ===
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use
Iface
255.255.255.255 0.0.0.0 255.255.255.255 UH 0 0 0 eth0
192.168.7.0 192.168.6.254 255.255.255.0 UG 0 0 0 eth0
192.168.6.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0
192.168.5.0 192.168.6.254 255.255.255.0 UG 0 0 0 eth0
192.168.4.0 192.168.6.254 255.255.255.0 UG 0 0 0 eth0
172.30.1.0 0.0.0.0 255.255.255.0 U 0 0 0 eth1
192.168.3.0 192.168.6.254 255.255.255.0 UG 0 0 0 eth0
192.168.2.0 192.168.6.254 255.255.255.0 UG 0 0 0 eth0
192.168.12.0 192.168.6.254 255.255.255.0 UG 0 0 0 eth0
192.168.11.0 192.168.6.254 255.255.255.0 UG 0 0 0 eth0
192.168.10.0 192.168.6.254 255.255.255.0 UG 0 0 0 eth0
192.168.9.0 192.168.6.254 255.255.255.0 UG 0 0 0 eth0
192.168.254.0 0.0.0.0 255.255.255.0 U 0 0 0 eth2
192.168.8.0 192.168.6.254 255.255.255.0 UG 0 0 0 eth0
127.0.0.0 0.0.0.0 255.0.0.0 U 0 0 0 lo
0.0.0.0 172.30.1.254 0.0.0.0 UG 0 0 0 eth1
=== Detail route output ===

Good day.

Sincerely yours,
responder