Re: [DNSOP] I-D Action: draft-ietf-dnsop-dns-tcp-requirements-05.txt

Paul Vixie <paul@redbarn.org> Thu, 05 December 2019 00:05 UTC

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To: "Wessels, Duane" <dwessels=40verisign.com@dmarc.ietf.org>
Cc: Puneet Sood <puneets=40google.com@dmarc.ietf.org>, "dnsop@ietf.org" <dnsop@ietf.org>
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From: Paul Vixie <paul@redbarn.org>
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Subject: Re: [DNSOP] I-D Action: draft-ietf-dnsop-dns-tcp-requirements-05.txt
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Wessels, Duane wrote on 2019-12-04 14:22:
> 
> ...
>     DNS messages over TCP are in no way guaranteed to arrive in single
>     segments.  In fact, a clever attacker might attempt to hide certain
>     messages by forcing them over very small TCP segments.  Applications
>     that capture network packets (e.g., with libpcap [libpcap]) SHOULD be
>     prepared to implement and perform full TCP segment reassembly.
>     dnscap [dnscap] is an open-source example of a DNS logging program
>     that implements TCP reassembly.
> 
>     Developers SHOULD also keep in mind connection reuse, query
>     pipelining, and out-of-order responses when building and testing DNS
>     monitoring applications.

i suggest a reference to 'dnstap' here, as a server-integrated 
monitoring protocol intended to facilitate wide scale dns monitoring.

-- 
P Vixie