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Re: [TLS] Session Lifetime

Martin Rex <mrex@sap.com> Thu, 18 November 2010 02:50 UTC

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From: Martin Rex <mrex@sap.com>
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To: mike-list@pobox.com
Date: Thu, 18 Nov 2010 03:51:23 +0100
In-Reply-To: <4CE484F1.2010403@pobox.com> from "Michael D'Errico" at Nov 17, 10 05:44:17 pm
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Cc: tls@ietf.org
Subject: Re: [TLS] Session Lifetime
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Michael D'Errico wrote:
> 
> Can someone point me to a document that explains why TLS
> sessions should expire within minutes of creation, as is
> the current practice (that I'm aware of)?

I am only aware of an upper lifetime limit of 24h for cached TLS session
in the SSLv3 and TLS specs, e.g. here:

http://tools.ietf.org/html/rfc5246.txt#appendix-F.1.4

For our apps I'm currently shipping a default session cache lifetime
of 15 minutes for the server and 30 minutes for the client.
Although this is a fairly short lifetime, it is perfectly sufficient
to achieve an acceptable ratio of full-HS/resume-HS.
Customers can finetune session cache size and cache lifetime.

I don't know what other implementations and apps are using.

-Martin

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