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RE: TOS copying considered harmful
h> IPsec is a security protocol, thus it is appropriate for it to
> include explicit controls when security-relevant mapping takes place
> relevant to a tunnel. By the way, it's not traffic analysis per se
> that is the major concern. The concern is that a Trojan Horse
> "behind" the IPsec implementation uses the TOS field to exfiltrate
> data.
And if the network beyond the tunnel egress is using that field to
determine which packets get what QoS-based services, there
are also possible denial of service attacks based on modifying
the field in the outer header of tunneled traffic.
For the record, I like Steve's proposal for modifications to RFC 2401's
rules for tunnel header processing, and there's text in a number of
diffserv RFCs that was written in anticipation/hope of such changes
(e.g., see p.30 of RFC 2475). I would expect that specification of
these changes would be accompanied by guidance on their proper
use and warning about security risks that may make them
inappropriate to configure/use in some situations, right?
--David
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David L. Black, Senior Technologist
EMC Corporation, 42 South St., Hopkinton, MA 01748
+1 (508) 435-1000 x75140 FAX: +1 (508) 497-8500
black_david@emc.com Mobile: +1 (978) 394-7754
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