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Re: [v6ops] IPv6 link-local traffic questions

Jen Linkova <furry13@gmail.com> Mon, 30 March 2020 04:44 UTC

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From: Jen Linkova <furry13@gmail.com>
Date: Mon, 30 Mar 2020 15:43:58 +1100
Message-ID: <CAFU7BAQhD3zx8Fv6M+VrrNe7=H8zmyi75P+CYQfY9fFOvf-MfA@mail.gmail.com>
Subject: Re: [v6ops] IPv6 link-local traffic questions
To: Brian E Carpenter <brian.e.carpenter@gmail.com>
Cc: Owen DeLong <owen@delong.com>, Erik Kline <ek.ietf@gmail.com>, V6 Ops List <v6ops@ietf.org>, 6man <6man@ietf.org>
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On Wed, Mar 25, 2020 at 1:04 PM Brian E Carpenter
<brian.e.carpenter@gmail.com> wrote:
> > If you use a hop limit of 1, then a remote attacker only needs to craft a packet with the correct initial hop limit to ensure that it arrives on
> > your link what the appropriate remaining hop limit of 1.
>
> Only if the router violates the spec:
> "  Routers must not forward any packets with Link-Local source or
>    destination addresses to other links." [RFC4291]
> Do we have any evidence of routers that are broken in this way?

I've seen it a few years ago - a few routers (same vendor, based on
EUI-64 based interface IDs) somewhere far far away were sending ICMPv6
errors (packet too big) to my border routers using their link-local
addresses as a source. Those packets successfully reached my network
and got dropped...It was while ago but I'm not sure how much the
situation has improved.


-- 
SY, Jen Linkova aka Furry

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