Address jgh notes re OpenSSL

[users/heiko/exim.git] / doc / doc-txt / experimental-spec.txt

diff --git a/doc/doc-txt/experimental-spec.txt b/doc/doc-txt/experimental-spec.txt
index d5140d58beb256030628460238862e770f2ec09b..149598ee8934b5465983a5271cd9634a65688bb6 100644 (file)
--- a/doc/doc-txt/experimental-spec.txt
+++ b/doc/doc-txt/experimental-spec.txt
@@ -430,14 +430,12 @@ package controlled locations (/usr/include and /usr/lib).
 
 2. Use the following global settings to configure DMARC:
 
 
 2. Use the following global settings to configure DMARC:
 

-Optional:
+Required:

 dmarc_tld_file      Defines the location of a text file of valid
                     top level domains the opendmarc library uses
                     during domain parsing. Maintained by Mozilla,
                     the most current version can be downloaded
                     from a link at http://publicsuffix.org/list/.
 dmarc_tld_file      Defines the location of a text file of valid
                     top level domains the opendmarc library uses
                     during domain parsing. Maintained by Mozilla,
                     the most current version can be downloaded
                     from a link at http://publicsuffix.org/list/.

-                    If unset, "/etc/exim/opendmarc.tlds" (hardcoded)
-                    is used.

 
 Optional:
 dmarc_history_file  Defines the location of a file to log results
 
 Optional:
 dmarc_history_file  Defines the location of a file to log results


@@ -548,9 +546,8 @@ expansion variables are available:
     are "none", "reject" and "quarantine".  It is blank when there
     is any error, including no DMARC record.
 
     are "none", "reject" and "quarantine".  It is blank when there
     is any error, including no DMARC record.
 

-  o $dmarc_ar_header
-    This is the entire Authentication-Results header which you can
-    add using an add_header modifier.
+A now-redundant variable $dmarc_ar_header has now been withdrawn.
+Use the ${authresults } expansion instead.

 
 
 5. How to enable DMARC advanced operation:
 
 
 5. How to enable DMARC advanced operation:


@@ -756,6 +753,56 @@ to your Local/Makefile. (Re-)build/install exim. exim -d should show
 Experimental_QUEUEFILE in the line "Support for:".
 
 
 Experimental_QUEUEFILE in the line "Support for:".
 
 

+ARC support
+-----------
+Specification: https://tools.ietf.org/html/draft-ietf-dmarc-arc-protocol-11
+Note that this is not an RFC yet, so may change.
+
+ARC is intended to support the utility of SPF and DKIM in the presence of
+intermediaries in the transmission path - forwarders and mailinglists -
+by establishing a cryptographically-signed chain in headers.
+
+Normally one would only bother doing ARC-signing when functioning as
+an intermediary.  One might do verify for local destinations.
+
+ARC uses the notion of a "ADministrative Management Domain" (ADMD).
+Described in RFC 5598 (section 2.3), this is essentially the set of
+mail-handling systems that the mail transits.  A label should be chosen to
+identify the ADMD.  Messages should be ARC-verified on entry to the ADMD,
+and ARC-signed on exit from it.
+
+
+Verification
+--
+An ACL condition is provided to perform the "verifier actions" detailed
+in section 6 of the above specification.  It may be called from the DATA ACL
+and succeeds if the result matches any of a given list.
+It also records the highest ARC instance number (the chain size)
+and verification result for later use in creating an Authentication-Results:
+standard header.
+
+  verify = arc/<acceptable_list>   none:fail:pass
+
+  add_header = :at_start:${authresults {<admd-identifier>}}
+
+       Note that it would be wise to strip incoming messages of A-R headers
+       that claim to be from our own <admd-identifier>.
+
+There are two new variables: $arc_state and $arc_state_reason.
+
+Receive log lines for an ARC pass will be tagged "ARC".
+
+
+Signing
+--
+arc_sign = <admd-identifier> : <selector> : <privkey>
+An option on the smtp transport, which constructs and prepends to the message
+an ARC set of headers.  The textually-first Authentication-Results: header
+is used as a basis (you must have added one on entry to the ADMD).
+Expanded; if unset, empty or forced-failure then no signing is done.
+
+
+

 --------------------------------------------------------------
 End of file
 --------------------------------------------------------------
 --------------------------------------------------------------
 End of file
 --------------------------------------------------------------