Hi Eric, >> If I understand correctly, packets sent to the all-ones >> broadcast address only go out through a single interface. > > I have some blur memories about this kind of issue, so my > answer my be wrong on some points...
It turns out you are exactly right on all points. :-) >> My question is threefold: >> >> 1. Why doesn't Linux send 255.255.255.255 packages >> through all network interfaces? (I realize that >> this is probably not a Linux-specific question.) > > IIRC, Linux treats 255.255.255.255 as a normal IP address. > Therefore it will follow the route for such an address and > select the interface it is associated (probably eth0 if > you are on a LAN). That makes a lot of sense, and it appears to be the case. >> 2. How does it choose which interface to send through? >> My first guess was that it just took the first >> Ethernet interface and used that for broadcasting. >> But playing around with nameif, this seems not to >> be the case. > > cf 1 > >> 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. > Hope this help, even if my memory is a bit confused, Yes, it did help. Thanks a bunch, Eric! Your memory seems to be in great shape. :-) Regards, -- Daniel Brockman <[EMAIL PROTECTED]> - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
