DNS Zone Transfer-over-TLS
draft-ietf-dprive-xfr-over-tls-04
dprive W. Toorop
Internet-Draft NLnet Labs
Updates: 1995, 5936, 7766 (if approved) S. Dickinson
Intended status: Standards Track Sinodun IT
Expires: May 27, 2021 S. Sahib
P. Aras
A. Mankin
Salesforce
November 23, 2020
DNS Zone Transfer-over-TLS
draft-ietf-dprive-xfr-over-tls-04
Abstract
DNS zone transfers are transmitted in clear text, which gives
attackers the opportunity to collect the content of a zone by
eavesdropping on network connections. The DNS Transaction Signature
(TSIG) mechanism is specified to restrict direct zone transfer to
authorized clients only, but it does not add confidentiality. This
document specifies use of TLS, rather then clear text, to prevent
zone content collection via passive monitoring of zone transfers:
XFR-over-TLS (XoT). Additionally, this specification updates
RFC1995, RFC5936 and RFC7766.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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time. It is inappropriate to use Internet-Drafts as reference
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This Internet-Draft will expire on May 27, 2021.
Copyright Notice
Copyright (c) 2020 IETF Trust and the persons identified as the
document authors. All rights reserved.
Toorop, et al. Expires May 27, 2021 [Page 1]
Internet-Draft XFR-over-TLS November 2020
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Document work via GitHub . . . . . . . . . . . . . . . . . . 5
3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5
4. Use Cases for XFR-over-TLS . . . . . . . . . . . . . . . . . 6
4.1. Threat model . . . . . . . . . . . . . . . . . . . . . . 6
5. Connection and Data Flows in Existing XFR Mechanisms . . . . 7
5.1. AXFR Mechanism . . . . . . . . . . . . . . . . . . . . . 7
5.2. IXFR Mechanism . . . . . . . . . . . . . . . . . . . . . 9
5.3. Data Leakage of NOTIFY and SOA Message Exchanges . . . . 11
5.3.1. NOTIFY . . . . . . . . . . . . . . . . . . . . . . . 11
5.3.2. SOA . . . . . . . . . . . . . . . . . . . . . . . . . 11
6. Updates to existing specifications . . . . . . . . . . . . . 11
6.1. Update to RFC1995 for IXFR-over-TCP . . . . . . . . . . . 12
6.2. Update to RFC5936 for AXFR-over-TCP . . . . . . . . . . . 13
6.3. Updates to RFC1995 and RFC5936 for XFR-over-TCP . . . . . 13
6.3.1. Connection reuse . . . . . . . . . . . . . . . . . . 13
6.3.2. AXFRs and IXFRs on the same connection . . . . . . . 13
6.3.3. XFR limits . . . . . . . . . . . . . . . . . . . . . 14
6.3.4. The edns-tcp-keepalive EDNS0 Option . . . . . . . . . 14
6.3.5. Backwards compatibility . . . . . . . . . . . . . . . 15
6.4. Update to RFC7766 . . . . . . . . . . . . . . . . . . . . 15
7. XoT specification . . . . . . . . . . . . . . . . . . . . . . 16
7.1. TLS versions . . . . . . . . . . . . . . . . . . . . . . 16
7.2. Port selection . . . . . . . . . . . . . . . . . . . . . 16
7.3. High level XoT descriptions . . . . . . . . . . . . . . . 16
7.4. XoT transfers . . . . . . . . . . . . . . . . . . . . . . 18
7.5. XoT connections . . . . . . . . . . . . . . . . . . . . . 19
7.6. XoT vs ADoT . . . . . . . . . . . . . . . . . . . . . . . 19
7.7. Response RCODES . . . . . . . . . . . . . . . . . . . . . 20
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