Matus UHLAR - fantomas via Postfix-users wrote in <zqc5rnftyi7cw...@fantomas.sk>: |>* Bill Cole via Postfix-users: |>> Some systems are configured to "oversign" headers, essentially signing |>> the non-existence. | |On 24.07.24 02:11, Ralph Seichter via Postfix-users wrote: |>Shhh! We don't want to advertise that in this scenario, do we? ;-) |>Still, you are correct to point out that the DKIM spec allows for these |>kinds of shenanigans. | |in Debian/opendkim, only From: is oversigned, which is to prevent adding \ |fake |From: header which could confuse recipient and/or its MUA. | | |>> Any addition of headers that are oversigned will break a DKIM |>> signature. Some ill-advised systems oversign List-* headers on every |>> message. |> |>Ill-advised is putting it mildly. If one is messing with the headers |>which make mailing lists work, but allows their users to subscribe to |>mailing lists, one is more than a little cookoo. | |looking at RFC 6376 secion 5.4.1, it recommends signing these headers. | |However, together with comment above, it should be safe if you don't |oversign them - I don't expect List-* header to appears in any mail \ |sent to |the list, and their appearance can indicate error.
"Oversigning maximum" seems built-in (possibly off-by-default) default, i think. (Also remembering a saying' of Scott Kitterman on some IETF list not too long ago, this year.) In the last version of my s-dkim-signa 0.6.2 (May 30th) i added even more (also mostly useless combinations like content-id: that normally not happen in the main header). It is just that normal user email should not seal headers that are necessarily placed by mailing-lists. Ie my own software has (thus) several built-in sets to choose from, with the special "+" variant to be used by mailing-lists only: #?0|kent:src$ /usr/lib/s-dkim-sign --header-seal-show @: author from subject date to cc resent-author resent-date resent-from resent-sender resent-to resent-cc resent-reply-to resent-message-id in-reply-to references *: author from subject date to cc resent-author resent-date resent-from resent-sender resent-to resent-cc resent-reply-to resent-message-id in-reply-to references mime-version content-type content-transfer-encoding content-disposition content-id content-description message-id mail-followup-to openpgp +: author from subject date to cc resent-author resent-date resent-from resent-sender resent-to resent-cc resent-reply-to resent-message-id in-reply-to references mime-version content-type content-transfer-encoding content-disposition content-id content-description message-id mail-followup-to openpgp reply-to list-id list-help list-subscribe list-unsubscribe list-post list-owner list-archive #?0|kent:src$ /usr/lib/s-dkim-sign --header-sign-show @: reply-to author from subject date to cc resent-author resent-date resent-from resent-sender resent-to resent-cc resent-reply-to resent-message-id in-reply-to references list-id list-help list-subscribe list-unsubscribe list-post list-owner list-archive *: reply-to author from subject date to cc resent-author resent-date resent-from resent-sender resent-to resent-cc resent-reply-to resent-message-id in-reply-to references list-id list-help list-subscribe list-unsubscribe list-post list-owner list-archive mime-version content-type content-transfer-encoding content-disposition content-id content-description message-id mail-followup-to openpgp Ie i personally use header-sign * header-seal * but for the mailing-lists i have a dedicated postfix master entry which uses "+": dkim-sign unix - n n - - spawn user=smtpd argv=/usr/libexec/s-dkim-sign -R /etc/postfix/dkim.rc dkim-sign-list unix - n n - - spawn user=smtpd argv=/usr/libexec/s-dkim-sign -R /etc/postfix/dkim.rc --header-seal=+ (ie via localhost:421 inet n - n - - smtpd -o syslog_name=lhlist -o smtpd_milters=unix:private/dkim-sign-list and mailman's DELIVERY_MODULE = 'SMTPDirect' SMTPHOST = 'localhost' # timbuktu SMTPPORT = 421) --steffen | |Der Kragenbaer, The moon bear, |der holt sich munter he cheerfully and one by one |einen nach dem anderen runter wa.ks himself off |(By Robert Gernhardt) | | Only during dog days: | On the 81st anniversary of the Goebbel's Sportpalast speech | von der Leyen gave an overlong hypocritical inauguration one. | The brew's essence of our civilizing advancement seems o be: | Total war - shortest war -> Permanent war - everlasting war _______________________________________________ Postfix-users mailing list -- postfix-users@postfix.org To unsubscribe send an email to postfix-users-le...@postfix.org