Re: [quicwg/base-drafts] The method of identifying "the same server" (#3155)

Kazuho Oku <> Mon, 04 November 2019 13:55 UTC

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Date: Mon, 04 Nov 2019 05:55:24 -0800
From: Kazuho Oku <>
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Subject: Re: [quicwg/base-drafts] The method of identifying "the same server" (#3155)
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> If there is only a single user behind an IP, a party that can observe all traffic to load balancer "a" can know who is connecting to "c" and "b" just by matching on the src ip and seeing that they are the same.

I think the hidden assumption in your argument is that the client is connecting to "b" and "c" at the same time. When that assumption is met, I think you are correct that the attack is only viable when the client is behind a NAT.

But it could also be the case that the client first connects to "c", disconnects, then connect to "b" using the token obtained from "c" from a different address. In that case, the attack becomes concerning even when the client is not behind a NAT.

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