X-Git-Url: https://git.exim.org/exim.git/blobdiff_plain/f926e27276301de1e2fd011b7edcd1b85d8c4754..bdf9ce828c5e29351eabbd29c88c459522811b67:/src/src/configure.default

diff --git a/src/src/configure.default b/src/src/configure.default
index c16221fc1..4209ae8c1 100644
--- a/src/src/configure.default
+++ b/src/src/configure.default
@@ -40,6 +40,7 @@
 ######################################################################
 #                    MAIN CONFIGURATION SETTINGS                     #
 ######################################################################
+#
 
 # Specify your host's canonical name here. This should normally be the fully
 # qualified "official" name of your host. If this option is not set, the
@@ -152,6 +153,9 @@ acl_smtp_data = acl_check_data
 # tls_certificate = /etc/ssl/exim.crt
 # tls_privatekey = /etc/ssl/exim.pem
 
+# For OpenSSL, prefer EC- over RSA-authenticated ciphers
+# tls_require_ciphers = ECDSA:RSA:!COMPLEMENTOFDEFAULT
+
 # In order to support roaming users who wish to send email from anywhere,
 # you may want to make Exim listen on other ports as well as port 25, in
 # case these users need to send email from a network that blocks port 25.
@@ -221,6 +225,13 @@ never_users = root
 host_lookup = *
 
 
+# The setting below causes Exim to try to initialize the system resolver
+# library with DNSSEC support.  It has no effect if your library lacks
+# DNSSEC support.
+
+dns_dnssec_ok = 1
+
+
 # The settings below cause Exim to make RFC 1413 (ident) callbacks
 # for all incoming SMTP calls. You can limit the hosts to which these
 # calls are made, and/or change the timeout that is used. If you set
@@ -236,6 +247,13 @@ host_lookup = *
 #rfc1413_query_timeout = 5s
 
 
+# Enable an efficiency feature.  We advertise the feature; clients
+# may request to use it.  For multi-recipient mails we then can
+# reject or accept per-user after the message is received.
+#
+prdr_enable = true
+
+
 # By default, Exim expects all envelope addresses to be fully qualified, that
 # is, they must contain both a local part and a domain. If you want to accept
 # unqualified addresses (just a local part) from certain hosts, you can specify
@@ -249,6 +267,13 @@ host_lookup = *
 # and/or qualify_recipient (see above).
 
 
+# Unless you run a high-volume site you probably want more logging
+# detail than the default.  Adjust to suit.
+
+log_selector = +smtp_protocol_error +smtp_syntax_error \
+	+tls_certificate_verified
+
+
 # If you want Exim to support the "percent hack" for certain domains,
 # uncomment the following line and provide a list of domains. The "percent
 # hack" is the feature by which mail addressed to x%y@z (where z is one of
@@ -315,6 +340,18 @@ timeout_frozen_after = 7d
 # accept_8bitmime = false
 
 
+# Exim does not make use of environment variables itself. However,
+# libraries that Exim uses (e.g. LDAP) depend on specific environment settings.
+# There are two lists: keep_environment for the variables we trust, and
+# add_environment for variables we want to set to a specific value.
+# Note that TZ is handled separately by the timezone runtime option
+# and TIMEZONE_DEFAULT buildtime option.
+
+# keep_environment = ^LDAP
+# add_environment = PATH=/usr/bin::/bin
+
+
+
 ######################################################################
 #                       ACL CONFIGURATION                            #
 #         Specifies access control lists for incoming SMTP mail      #
@@ -422,6 +459,11 @@ acl_check_rcpt:
           control       = submission
           control       = dkim_disable_verify
 
+  # Insist that a HELO/EHLO was accepted.
+
+  require message	= nice hosts say HELO first
+          condition	= ${if def:sender_helo_name}
+
   # Insist that any other recipient address that we accept is either in one of
   # our local domains, or is in a domain for which we explicitly allow
   # relaying. Any other domain is rejected as being unacceptable for relaying.
@@ -478,6 +520,19 @@ acl_check_rcpt:
 
 acl_check_data:
 
+  # Deny if the message contains an overlong line.  Per the standards
+  # we should never receive one such via SMTP.
+  #
+  deny    message    = maximum allowed line length is 998 octets, \
+                       got $max_received_linelength
+          condition  = ${if > {$max_received_linelength}{998}}
+
+  # Deny if the headers contain badly-formed addresses.
+  #
+  deny	  !verify =	header_syntax
+	  message =	header syntax
+	  log_message = header syntax ($acl_verify_message)
+
   # Deny if the message contains a virus. Before enabling this check, you
   # must install a virus scanner and set the av_scanner option above.
   #
@@ -545,6 +600,7 @@ dnslookup:
   ignore_target_hosts = 0.0.0.0 : 127.0.0.0/8
 # if ipv6-enabled then instead use:
 # ignore_target_hosts = <; 0.0.0.0 ; 127.0.0.0/8 ; ::1
+  dnssec_request_domains = *
   no_more
 
 
@@ -557,7 +613,7 @@ dnslookup:
 # smarthost:
 #   driver = manualroute
 #   domains = ! +local_domains
-#   transport = remote_smtp
+#   transport = smarthost_smtp
 #   route_data = MAIL.HOSTNAME.FOR.CENTRAL.SERVER.EXAMPLE
 #   ignore_target_hosts = <; 0.0.0.0 ; 127.0.0.0/8 ; ::1
 #   no_more
@@ -670,9 +726,49 @@ begin transports
 
 
 # This transport is used for delivering messages over SMTP connections.
+# Refuse to send any message with over-long lines, which could have
+# been received other than via SMTP. The use of message_size_limit to
+# enforce this is a red herring.
 
 remote_smtp:
   driver = smtp
+  message_size_limit = ${if > {$max_received_linelength}{998} {1}{0}}
+.ifdef _HAVE_DANE
+  dnssec_request_domains = *
+  hosts_try_dane = *
+.endif
+
+
+# This transport is used for delivering messages to a smarthost, if the
+# smarthost router is enabled.  This starts from the same basis as
+# "remote_smtp" but then turns on various security options, because
+# we assume that if you're told "use smarthost.example.org as the smarthost"
+# then there will be TLS available, with a verifiable certificate for that
+# hostname, using decent TLS.
+
+smarthost_smtp:
+  driver = smtp
+  message_size_limit = ${if > {$max_received_linelength}{998} {1}{0}}
+  multi_domain
+  #
+.ifdef _HAVE_TLS
+  # Comment out any of these which you have to, then file a Support
+  # request with your smarthost provider to get things fixed:
+  hosts_require_tls = *
+  tls_sni = $host
+  tls_verify_hosts = *
+  # As long as tls_verify_hosts is enabled, this won't matter, but if you
+  # have to comment it out then this will at least log whether you succeed
+  # or not:
+  tls_try_verify_hosts = *
+  #
+.ifdef _HAVE_OPENSSL
+  tls_require_ciphers = HIGH:!aNULL:@STRENGTH
+.endif
+.ifdef _HAVE_GNUTLS
+  tls_require_ciphers = SECURE192:-VERS-SSL3.0:-VERS-TLS1.0:-VERS-TLS1.1
+.endif
+.endif
 
 
 # This transport is used for local delivery to user mailboxes in traditional