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Re: [TLS] SCSVs and SSLv3 fallback

Hanno Böck <hanno@hboeck.de> Thu, 04 April 2013 21:34 UTC

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Date: Thu, 04 Apr 2013 23:34:02 +0200
From: Hanno Böck <hanno@hboeck.de>
To: Trevor Perrin <trevp@trevp.net>
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Cc: tls@ietf.org
Subject: Re: [TLS] SCSVs and SSLv3 fallback
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On Thu, 4 Apr 2013 14:02:27 -0700
Trevor Perrin <trevp@trevp.net> wrote:

> I've heard (anecdotally) that HTTPS between browsers and webservers
> who are both TLS-capable sometimes results in SSLv3 connections.
> Presumably this is due to firewall interference with the TLS
> handshake, causing browsers to retry an SSLv3 handshake.

This happens pretty often if you have a unreliable (e.g. mobile)
internet connection. Mozilla/nss-Bug about it:
https://bugzilla.mozilla.org/show_bug.cgi?id=450280

And it's a serious problem if you're using Server Name
Indication (SNI) for more than one SSL cert on one IP. The "solution" I
found for our case was that I found it tolerable today to disable SSLv3
on the server side. However, I'm not really happy with that browser
fallback behaviour, it's a serious pitfall for the use of SNI.



-- 
Hanno Böck		mail/jabber: hanno@hboeck.de
GPG: BBB51E42		http://www.hboeck.de/

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