From f294ddcca7fbe20de788053bfba1cc9c8417ddd8 Mon Sep 17 00:00:00 2001 From: Micah Date: Tue, 5 Jul 2016 11:50:41 -0400 Subject: Use DANE/TLSA validation in postfix (#8141). Configure DNSSEC validation for client verification, giving us a stronger form of opportunistic TLS Change-Id: Iab92d4f593c4a5a44e3b694295096b0d7f687a37 --- puppet/modules/site_postfix/manifests/mx.pp | 33 +++++++++++++++++++++++++---- 1 file changed, 29 insertions(+), 4 deletions(-) (limited to 'puppet/modules/site_postfix') diff --git a/puppet/modules/site_postfix/manifests/mx.pp b/puppet/modules/site_postfix/manifests/mx.pp index 0b760eb4..2dac85f5 100644 --- a/puppet/modules/site_postfix/manifests/mx.pp +++ b/puppet/modules/site_postfix/manifests/mx.pp @@ -57,10 +57,6 @@ class site_postfix::mx { value => 'sha1'; 'relay_clientcerts': value => 'tcp:localhost:2424'; - # Note: we are setting this here, instead of in site_postfix::mx::smtp_tls - # because the satellites need to have a different value - 'smtp_tls_security_level': - value => 'may'; # reject inbound mail to system users # see https://leap.se/code/issues/6829 # this blocks *only* mails to system users, that don't appear in the @@ -90,6 +86,35 @@ class site_postfix::mx { value => 'permit_mynetworks'; 'postscreen_greet_action': value => 'enforce'; + # Level of DNS support in the Postfix SMTP client. Enable DNS lookups + # (default: empty). When empty, then the legacy "disable_dns_lookups" + # (default: no) parameter is used. Setting 'smtp_dns_support_level' to + # enabled sets the previous behavior with the new parameter. When set to + # 'dnssec" this enables DNSSEC lookups. + 'smtp_dns_support_level': + value => 'dnssec'; + + # http://www.postfix.org/TLS_README.html#client_tls_dane The "dane" level is + # a stronger form of opportunistic TLS that is resistant to man in the + # middle and downgrade attacks when the destination domain uses DNSSEC to + # publish DANE TLSA records for its MX hosts. If a remote SMTP server has + # "usable" (see RFC 6698) DANE TLSA records, the server connection will be + # authenticated. When DANE authentication fails, there is no fallback to + # unauthenticated or plaintext delivery. + # + # If TLSA records are published for a given remote SMTP server (implying TLS + # support), but are all "unusable" due to unsupported parameters or + # malformed data, the Postfix SMTP client will use mandatory unauthenticated + # TLS. Otherwise, when no TLSA records are published, the Postfix SMTP + # client behavior is the same as with may. + # + # This requires postfix to be able to send its DNS queries to a recursive + # DNS nameserver that is able to validate the signed records + # + # Note: we are setting this here, instead of in site_postfix::mx::smtp_tls + # because the satellites need to have a different value + 'smtp_tls_security_level': + value => 'dane'; } # Make sure that the cleanup serivce is not chrooted, otherwise it cannot -- cgit v1.2.3