Messages in this thread |  | | Date | Thu, 06 Sep 2001 18:05:30 +0100 | From | Alex Bligh - linux-kernel <> | Subject | Re: notion of a local address [was: Re: ioctl SIOCGIFNETMASK: ip alias bug 2.4.9 and 2.2.19] |
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Andrey,
--On Thursday, September 06, 2001 8:38 PM +0400 Andrey Savochkin <saw@saw.sw.com.sg> wrote:
> Hell, how else could you define the notion of a local address as not the > address which responds to pings without external network, the address for > which
So the remote end of a looped /30 serial line is now a local address? Can you bind() to 127.0.0.2? In any case, all you've found is a peculiarity of the loopback driver. So send a patch.
The read RFC1122. (hosts & routers requirements). Not only does this define local address, but specifically writes:
3.3.4.2 Multihoming Requirements
The following general rules apply to the selection of an IP source address for sending a datagram from a multihomed host.
(1) If the datagram is sent in response to a received datagram, the source address for the response SHOULD be the specific-destination address of the request. See Sections 4.1.3.5 and 4.2.3.7 and the "General Issues" section of [INTRO:1] for more specific requirements on higher layers.
Otherwise, a source address must be selected.
(2) An application MUST be able to explicitly specify the source address for initiating a connection or a request.
How can (2) be usefully true if the application cannot determine what the list of valid local addresses are? Or is your argument that all such addresses should be configured manually, rather than by the application? Which would not only be a rather odd point of view, but makes implementing things like BGP, which depends on being able to get the outbound interface address used for a session up to the higher layers, rather hard.
-- Alex Bligh - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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