RE: [2.4 PATCH] bugfix: ARP respond on all devices

3 messages, 3 authors, 2003-08-19 · open the first message on its own page

RE: [2.4 PATCH] bugfix: ARP respond on all devices

From: Richard Underwood <hidden>
Date: 2003-08-19 18:28:08

David S. Miller wrote:
quoted
	Which nicely sums up the bug, really.
Ok, then how would you propose to be able to send
packets out an interface _before_ we have addresses
assigned to it?
	IP packets you mean? You don't? ;) It would depend on why you're
doing it naturally. Mostly, I'd have thought that if a host doesn't have an
IP number it doesn't get to use ARP.
Linux allows that, and in fact it's a useful feature.

Consider MSG_DONTROUTE as well.
	Irrelevant, ARP should stick to resolving Layer 2 issues, not be
misused as some Layer 3 routeing protocol.
BTW, this ARP source address algorithm we use comes from
ipv6, it would be instructive to go and see why they do
things the way they do.
	If you'd like to give me a reference, I'd be happy to look at the
spec. It doesn't matter where you got the concept from, though - it's
flawed.

		Richard

Re: [2.4 PATCH] bugfix: ARP respond on all devices

From: David S. Miller <hidden>
Date: 2003-08-19 18:37:09

On Tue, 19 Aug 2003 19:16:18 +0100
Richard Underwood [off-list ref] wrote:
David S. Miller wrote:
quoted
Ok, then how would you propose to be able to send
packets out an interface _before_ we have addresses
assigned to it?
	IP packets you mean? You don't? ;) It would depend on why you're
doing it naturally. Mostly, I'd have thought that if a host doesn't have an
IP number it doesn't get to use ARP.
Of course it gets to use ARP, nothing prevents this.

If I know that IP X has my configuration information, I
have every right to send X a packet from zero-net to
ask for that information before I have any IP addresses
attached to the interface.

This is nothing wrong nor strange about this and we've
supported it for years.

Also, when one specifies a specific device in an output
address and we cannot find the IP part of the address
in the routing tables, we still procure a valid route for
the requester.

Besides normal IP addresses, multicast tools use these
facilities.

Re: [2.4 PATCH] bugfix: ARP respond on all devices

From: Bas Bloemsaat <hidden>
Date: 2003-08-19 19:02:47

quoted
quoted
Ok, then how would you propose to be able to send
packets out an interface _before_ we have addresses
assigned to it?
IP packets you mean? You don't? ;) It would depend on why you're
doing it naturally. Mostly, I'd have thought that if a host doesn't have
an
quoted
IP number it doesn't get to use ARP.
Of course it gets to use ARP, nothing prevents this.
Huh? RFC 826 states that the requesting arp packet sends the protocol
address of itself. So no address is no arp.

Allowing it to is a violation of that rfc

Regards,
Bas
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