Messages in this thread | | | Date | Thu, 28 Sep 2000 08:47:57 +0000 (GMT) | From | Julian Anastasov <> | Subject | Re: [patch] 2.4 version of my duplicate IP and MAC detection patch |
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Hello,
On Wed, 27 Sep 2000, Marc MERLIN wrote:
> > print messages for all these hidden addresses. They are not advertised > > and there is no problem caused from duplication. > > I thought about that, but isn't the shared IP just an IP alias and not the > primary IP? As far as I know, the machines which share the IP have a primary > IP and put that one in their ARP packets, so my patch should not complain.
Your code receives such requests from remote host:
"who-has ANY_IP tell SHARED_IP"
This broadcast request comes from host that advertises this SHARED_IP but the duplicate detection code in the local host warns about this IP because the same SHARED_IP is configured on the receiver (on hidden device, it is not advertised).
> That said, adding a flag that lets you disable the duplicate IP detection on > an interface basis wouldn't be a bad idea, I'll look into this.
If everything is handled correctly may be this flag is not needed. But in this case you have to check the hidden flag.
> > - sip=127.0.0.0/8, this address is shared but we "assume" it is not > > advertised from the neighbours > > Are you saying that some machines would ARP with a source IP of localhost? > That'd be pretty broken, wouldn't it? Or you talking about a kind of DOS > that would trigger warnings on all the machines? > (the dupe check could ignore that)
Yes, I see the messages are rate limited but sip=127/8 is possible to be generated from attacker (who knows):
"who-has ANY_IP tell 127.0.0.1"
May be you can look at the ip_route_input_slow(). Search for martian_source and how fib_validate_source is used. I'm not sure but it looks like the checks will be very complex.
> > - you work with ifa_address and not with ifa_local and ifa_mask. > > I'll look into this too. > > Thanks for your feedback. > Marc
Regards
-- Julian Anastasov <ja@ssi.bg>
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