DMARC Technology Overview
DMARC dkim.jp 2013 3 RFC draft-dmarc-base-00-02.txt p19 20 21 dkim.jp dkim.jp P2
1. DMARC 2. 3. DMARC Record 4. Identifier Alignment 5. ML, 6. ADSP 7. P3
DMARC http://www.dmarc.org/ Domain-based Message Authentication, Reporting and Conformance 2012 1 30 Sender Receiver P4
DKIM SPF P5
DKIM, SPF Sender: SPF pass Receiver: DKIM Receiver SPF DKIM Receiver DKIM, SPF Receiver Sender Receiver P6
3.4. Out Of Scope RFC5322.From display name From: "user@example.org via Bug Tracker" <support@example.com> P7
false positives Sender Receiver RFC draft 3.1. High-Level Requirements P8
P9
SPF hard/softfail, DKIM ADSP DMARC AFRF AFRF draft-ietf-marfauthfailurereport-10 DMARC www.dmarc.org SPF Policy ADSP SPS SPF RFC4408 OR AND DKIM RFC6376 DKIM ATPS RFC6541 SMTP RFC5322 DNS DNSSEC P10
DMARC Sender/Receiver DMARC From RFC5322.From Sender 1. SPF DKIM 2. 3. From 4. DMARC Record DNS TXT 5. Receiver 1. SPF DKIM 2. DMARC Record 3. 4. P11
DMARC 11.2. Determine Handling Policy SPF DKIM From DMARC pass the DMARC mechanism check fail the DMARC mechanism check DMARC / P12 quarantine reject or drop
DMARC Record From DMARC Record From: <info@example.co.jp> _dmarc.example.co.jp TXT v=dmarc1 ; p=none ; rf=afrf ; rua=mailto:reportdmarc@example.co.jp ; ruf=mailto:report-dmarc@example.co.jp v DMARC1 p none, quarantine, reject pct DMARC 0 100 rua URI mailto:aggrep@example.com ruf Failure URI mailto:auth-reports@example.com sp none, quarantine, reject adkim DKIM r, s aspf SPF r, s P13
http://sourceforge.net/projects/opendmarc/ DMARC - Google Apps http://support.google.com/a/bin/answer.py?hl=ja&hlrm=e n&answer=2466563 P14
DMARC Alignment RFC5322.From SPF: spf=pass RFC5321.MailFrom DKIM: dkim=pass d= r relaxed mode : RFC5322.From s strict mode : RFC5322.From a.b.c.d.example.com example.com : http://publicsuffix.org P15
Example 1: SPF in alignment: MAIL FROM: <sender@example.com> From: sender@example.com Date: Fri, Feb 15 2002 16:54:30-0800 To: receiver@example.org Subject: here's a sample Example 2: SPF in alignment parent : MAIL FROM: <sender@example.com> From: sender@child.example.com Date: Fri, Feb 15 2002 16:54:30-0800 To: receiver@example.org Subject: here's a sample Example 3: SPF not in alignment: MAIL FROM: <sender@sample.net> relax: example.com From: sender@child.example.com Date: Fri, Feb 15 2002 16:54:30-0800 To: receiver@example.org Subject: here's a sample child.example.com P16
Example 1: DKIM in alignment: DKIM-Signature: v=1;...; d=example.com;... From: sender@example.com Date: Fri, Feb 15 2002 16:54:30-0800 To: receiver@example.org Subject: here's a sample Example 2: DKIM in alignment parent : DKIM-Signature: v=1;...; d=example.com;... From: sender@child.example.com Date: Fri, Feb 15 2002 16:54:30-0800 To: receiver@example.org Subject: here's a sample Example 3: DKIM not in alignment: DKIM-Signature: v=1;...; d=sample.net;... From: sender@child.example.com Date: Fri, Feb 15 2002 16:54:30-0800 To: receiver@example.org Subject: here's a sample relax: child.example.com example.com P17
SPF DKIM DMARC Record P18 SPF Alignment DKIM Alignment 1 pass pass --- --- --- --- 2 pass pass in in Pass 3 pass --- in --- Pass 4 --- pass --- in Pass --- pass --- Not in Fail DMARC mechanism check fail fail --- --- Fail fail pass --- in Pass ML pass fail Not in --- Fail ML pass pass Not in Not in Fail pass pass Not in Not in Fail fail pass Not in Not in Fail
DMARC mechanism check Fail 1. ML Subject in alignment From DMARC ATPS Bounce RFC5321.MailFrom SPF in alignment Submission 587port envelope From P19
DKIM ADSP DKIM fail SPF ADSP discardable P20
P21