Re: [Fwbuilder-discussion] bug: Network Mask 255.255.255.254 ?
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From: Henrique de M. H. <hmh...@hm...> - 2011-10-28 17:28:56
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On Sat, 29 Oct 2011, Karl Auer wrote: > Then the two ends should have /32 addresses. If you use a /31 and use > the two addresses in such a network, then the two ends are in the same > subnet, and you have used the network and broadcast addresses of that > subnet. > > Hey, it might work - but I can see it being confusing at very least. And > the symptoms described suggest that FWBuilder is confused. IPv4 /31 networks are specified in RFC3021, which is nearly 11 years old. Any routing gear worth being called a router supports RFC3021. And yes, Linux supports it, in the sense that it *works*. However, the kernel will not help: it will fail to refuse idiotic requests from deprecated userspace like ifconfig to set up IP-directed broadcast adresses on the /31 network, which *will* immediately cause traffic to be dropped. You have to use iproute2 to set up such links, and you must NOT attempt to set any broadcast addresses. I'd be extremely surprised if at least OpenBSD and FreeBSD don't support RFC3021 in some way. -- "One disk to rule them all, One disk to find them. One disk to bring them all and in the darkness grind them. In the Land of Redmond where the shadows lie." -- The Silicon Valley Tarot Henrique Holschuh |