.set I " "
.macro copyyear
-2017
+2018
.endmacro
. /////////////////////////////////////////////////////////////////////////////
.vitem "&*${authresults{*&<&'authserv-id'&>&*}}*&"
.cindex authentication "results header"
.cindex headers "authentication-results:"
+.cindex authentication "expansion item"
This item returns a string suitable for insertion as an
&'Authentication-Results"'&
header line.
.code
add_header = :at_start:${authresults {$primary_hostname}}
.endd
+This is safe even if no authentication reselts are available.
.wen
user/password authenticator configuration might preserve the user name for use
in the routers. Note that this is not the same information that is saved in
&$sender_host_authenticated$&.
+
When a message is submitted locally (that is, not over a TCP connection)
the value of &$authenticated_id$& is normally the login name of the calling
process. However, a trusted user can override this by means of the &%-oMai%&
command line option.
+.new
+This second case also sets up inforamtion used by the
+&$authresults$& expansion item.
+.wen
.vitem &$authenticated_fail_id$&
.cindex "authentication" "fail" "id"
the result, the name is not accepted, and &$host_lookup_deferred$& is set to
&"1"&. See also &$sender_host_name$&.
+.new
+.cindex authentication "expansion item"
+Performing these checks sets up information used by the
+&$authresults$& expansion item.
+.wen
+
+
.vitem &$host_lookup_failed$&
.vindex "&$host_lookup_failed$&"
See &$host_lookup_deferred$&.
.vitem &$spf_header_comment$& &&&
&$spf_received$& &&&
&$spf_result$& &&&
+ &$spf_result_guessed$& &&&
&$spf_smtp_comment$&
These variables are only available if Exim is built with SPF support.
For details see section &<<SECSPF>>&.
option.
+.new
+.option dane_require_tls_ciphers smtp string&!! unset
+.cindex "TLS" "requiring specific ciphers for DANE"
+.cindex "cipher" "requiring specific"
+.cindex DANE "TLS ciphers"
+This option may be used to override &%tls_require_ciphers%& for connections
+where DANE has been determined to be in effect.
+If not set, then &%tls_require_ciphers%& will be used.
+Normal SMTP delivery is not able to make strong demands of TLS cipher
+configuration, because delivery will fall back to plaintext. Once DANE has
+been determined to be in effect, there is no plaintext fallback and making the
+TLS cipherlist configuration stronger will increase security, rather than
+counter-intuitively decreasing it.
+If the option expands to be empty or is forced to fail, then it will
+be treated as unset and &%tls_require_ciphers%& will be used instead.
+.wen
+
+
.option data_timeout smtp time 5m
This sets a timeout for the transmission of each block in the data portion of
the message. As a result, the overall timeout for a message depends on the size
client from which the message was received. This variable is empty if there was
no successful authentication.
+.new
+.cindex authentication "expansion item"
+Successful authentication sets up information used by the
+&$authresults$& expansion item.
+.wen
+
to this server, its A record, its TLSA record and any associated CNAME records must all be covered by
DNSSEC.
2) add TLSA DNS records. These say what the server certificate for a TLS connection should be.
-3) offer a server certificate, or certificate chain, in TLS connections which is traceable to the one
-defined by (one of?) the TSLA records
+3) offer a server certificate, or certificate chain, in TLS connections which is is anchored by one of the TLSA records.
There are no changes to Exim specific to server-side operation of DANE.
Support for client-side operation of DANE can be included at compile time by defining SUPPORT_DANE=yes
those who use &%hosts_require_ocsp%&, should consider the interaction with DANE in their OCSP settings.
-For client-side DANE there are two new smtp transport options, &%hosts_try_dane%& and &%hosts_require_dane%&.
-The latter variant will result in failure if the target host is not DNSSEC-secured.
+For client-side DANE there are three new smtp transport options, &%hosts_try_dane%&, &%hosts_require_dane%&
+and &%dane_require_tls_ciphers%&.
+The require variant will result in failure if the target host is not DNSSEC-secured.
DANE will only be usable if the target host has DNSSEC-secured MX, A and TLSA records.
will be required for the host. If it does not, the host will not
be used; there is no fallback to non-DANE or non-TLS.
+If DANE is requested and usable, then the TLS cipher list configuration
+prefers to use the option &%dane_require_tls_ciphers%& and falls
+back to &%tls_require_ciphers%& only if that is unset.
+This lets you configure "decent crypto" for DANE and "better than nothing
+crypto" as the default. Note though that while GnuTLS lets the string control
+which versions of TLS/SSL will be negotiated, OpenSSL does not and you're
+limited to ciphersuite constraints.
+
If DANE is requested and useable (see above) the following transport options are ignored:
.code
hosts_require_tls
before use.
The usual list-parsing of the content (see &<<SECTlistconstruct>>&) applies.
The following scanner types are supported in this release,
-.new
though individual ones can be included or not at build time:
-.wen
.vlist
.vitem &%avast%&
or host and port specifiers separated by white space.
The host may be a name or an IP address; the port is either a
single number or a pair of numbers with a dash between.
-Any further options are given, on separate lines,
-to the daemon as options before the main scan command.
+A list of options may follow. These options are interpreted on the
+Exim's side of the malware scanner, or are given on separate lines to
+the daemon as options before the main scan command.
+
+.new
+.cindex &`pass_unscanned`& "avast"
+If &`pass_unscanned`&
+is set, any files the Avast scanner can't scan (e.g.
+decompression bombs, or invalid archives) are considered clean. Use with
+care.
+.wen
+
For example:
.code
av_scanner = avast:/var/run/avast/scan.sock:FLAGS -fullfiles:SENSITIVITY -pup
+av_scanner = avast:/var/run/avast/scan.sock:pass_unscanned:FLAGS -fullfiles:SENSITIVITY -pup
av_scanner = avast:192.168.2.22 5036
.endd
If you omit the argument, the default path
PACK
.endd
-Only the first virus detected will be reported.
-
+If the scanner returns a temporary failure (e.g. license issues, or
+permission problems), the message is deferred and a paniclog entry is
+written. The usual &`defer_ok`& option is available.
.vitem &%aveserver%&
.cindex "virus scanners" "Kaspersky"
If the value of av_scanner points to a UNIX socket file or contains the
&`local`&
option, then the ClamAV interface will pass a filename containing the data
-to be scanned, which will should normally result in less I/O happening and be
+to be scanned, which should normally result in less I/O happening and be
more efficient. Normally in the TCP case, the data is streamed to ClamAV as
Exim does not assume that there is a common filesystem with the remote host.
be a valid RSA private key in ASCII armor (.pem file), including line breaks
.new
.next
-with GnuTLS 3.6.0 or later, be a valid Ed25519 private key (same format as above)
+with GnuTLS 3.6.0 or OpenSSL 1.1.1 or later,
+be a valid Ed25519 private key (same format as above)
.wen
.next
start with a slash, in which case it is treated as a file that contains
.endlist
.new
+To generate keys under OpenSSL:
+.code
+openssl genrsa -out dkim_rsa.private 2048
+openssl rsa -in dkim_rsa.private -out /dev/stdout -pubout -outform PEM
+.endd
+Take the base-64 lines from the output of the second command, concatenated,
+for the DNS TXT record.
+See section 3.6 of RFC6376 for the record specification.
+
+Under GnuTLS:
+.code
+certtool --generate-privkey --rsa --bits=2048 --password='' -8 --outfile=dkim_rsa.private
+certtool --load-privkey=dkim_rsa.private --pubkey-info
+.endd
+
Note that RFC 8301 says:
.code
Signers MUST use RSA keys of at least 1024 bits for all keys.
for some transition period.
The "_CRYPTO_SIGN_ED25519" macro will be defined if support is present
for EC keys.
+
+OpenSSL 1.1.1 and GnuTLS 3.6.0 can create Ed25519 private keys:
+.code
+openssl genpkey -algorithm ed25519 -out dkim_ed25519.private
+certtool --generate-privkey --key-type=ed25519 --outfile=dkim_ed25519.private
+.endd
+
+To produce the required public key value for a DNS record:
+.code
+openssl pkey -outform DER -pubout -in dkim_ed25519.private | tail -c +13 | base64
+certtool --load_privkey=dkim_ed25519.private --pubkey_info --outder | tail -c +13 | base64
+.endd
.wen
.option dkim_hash smtp string&!! sha256
containing the signature status and its details are set up during the
runtime of the ACL.
+.new
+.cindex authentication "expansion item"
+Performing verification sets up information used by the
+&$authresults$& expansion item.
+.wen
+
Calling the ACL only for existing signatures is not sufficient to build
more advanced policies. For that reason, the global option
&%dkim_verify_signers%&, and a global expansion variable
.vitem &%$dkim_algo%&
The algorithm used. One of 'rsa-sha1' or 'rsa-sha256'.
.new
-If running under GnuTLS 3.6.0 or later, may also be 'ed25519-sha256'.
+If running under GnuTLS 3.6.0 or OpenSSL 1.1.1 or later,
+may also be 'ed25519-sha256'.
The "_CRYPTO_SIGN_ED25519" macro will be defined if support is present
for EC keys.
.wen
DNS records is all that is required.
For verification, an ACL condition and an expansion lookup are provided.
+.new
+.cindex authentication "expansion item"
+Performing verification sets up information used by the
+&$authresults$& expansion item.
+.wen
+
.cindex SPF "ACL condition"
.cindex ACL "spf condition"
.vitem &%permerror%&
This indicates a syntax error in the SPF record of the queried domain.
-You may deny messages when this occurs. (Changed in 4.83)
+You may deny messages when this occurs.
.vitem &%temperror%&
This indicates a temporary error during all processing, including Exim's
SPF processing. You may defer messages when this occurs.
-(Changed in 4.83)
-
-.vitem &%err_temp%&
-Same as permerror, deprecated in 4.83, will be removed in a future release.
-
-.vitem &%err_perm%&
-Same as temperror, deprecated in 4.83, will be removed in a future release.
.endlist
You can prefix each string with an exclamation mark to invert
one of pass, fail, softfail, none, neutral, permerror or
temperror.
+.vitem &$spf_result_guessed$&
+.vindex &$spf_result_guessed$&
+ This boolean is true only if a best-guess operation was used
+ and required in order to obtain a result.
+
.vitem &$spf_smtp_comment$&
.vindex &$spf_smtp_comment$&
This contains a string that can be used in a SMTP response
git://git.exim.org / users / jgh / exim.git / blobdiff