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Downgrade TLS settings for port 25, partially reverting f53b18ebb9

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Port 25 now is aligned with Mozilla's "Old" recommendations at https://ssl-config.mozilla.org/#server=postfix&server-version=3.3.0&config=old&openssl-version=1.1.1.

See #1705
This commit is contained in:
Joshua Tauberer 2020-01-20 05:50:52 -05:00
parent a67f90593d
commit 30885bcc8a
1 changed files with 22 additions and 14 deletions
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36
setup/mail-postfix.sh
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@ -80,7 +80,7 @@ tools/editconf.py /etc/postfix/main.cf \
# OpenDKIM milter only. See dkim.sh.
# * Even though we dont allow auth over non-TLS connections (smtpd_tls_auth_only below, and without auth the client cant
# send outbound mail), don't allow non-TLS mail submission on this port anyway to prevent accidental misconfiguration.
# By putting this setting here we leave opportunistic TLS on incoming mail at default cipher settings (any cipher is better than none).
# Setting smtpd_tls_security_level=encrypt also triggers the use of the 'mandatory' settings below.
# * Give it a different name in syslog to distinguish it from the port 25 smtpd server.
# * Add a new cleanup service specific to the submission service ('authclean')
# that filters out privacy-sensitive headers on mail being sent out by
@ -106,25 +106,34 @@ cp conf/postfix_outgoing_mail_header_filters /etc/postfix/outgoing_mail_header_f
sed -i "s/PRIMARY_HOSTNAME/$PRIMARY_HOSTNAME/" /etc/postfix/outgoing_mail_header_filters
sed -i "s/PUBLIC_IP/$PUBLIC_IP/" /etc/postfix/outgoing_mail_header_filters
# Enable TLS on these and all other connections (i.e. ports 25 *and* 587) and
# require TLS before a user is allowed to authenticate. This also makes
# opportunistic TLS available on *incoming* mail.
# Set stronger DH parameters, which via openssl tend to default to 1024 bits.
# Use Mozilla's "Intermediate" TLS recommendations from https://ssl-config.mozilla.org/#server=postfix&server-version=3.3.0&config=intermediate&openssl-version=1.1.1
# (but use and override the "high" cipher list so we don't conflict with the
# more permissive settings for outgoing mail).
# Enable TLS on incoming connections. It is not required on port 25, allowing for opportunistic
# encryption. On port 587 it is mandatory (see above). Shared and non-shared settings are
# given here. Shared settings include:
# * Require TLS before a user is allowed to authenticate.
# * Set the path to the server TLS certificate and 2048-bit DH parameters for old DH ciphers.
# For port 25 only:
# * Disable extremely old versions of TLS and extremely unsafe ciphers, but some mail servers out in
# the world are very far behind and if we disable too much, they may not be able to use TLS and
# won't fall back to cleartext. So we don't disable too much. smtpd_tls_exclude_ciphers applies to
# both port 25 and port 587, but because we override the cipher list for both, it probably isn't used.
# Use Mozilla's "Old" recommendations at https://ssl-config.mozilla.org/#server=postfix&server-version=3.3.0&config=old&openssl-version=1.1.1
# For port 587 (via the 'mandatory' settings):
# * Use Mozilla's "Intermediate" TLS recommendations from https://ssl-config.mozilla.org/#server=postfix&server-version=3.3.0&config=intermediate&openssl-version=1.1.1
# using and overriding the "high" cipher list so we don't conflict with the more permissive settings for port 25.
tools/editconf.py /etc/postfix/main.cf \
smtpd_tls_security_level=may\
smtpd_tls_auth_only=yes \
smtpd_tls_cert_file=$STORAGE_ROOT/ssl/ssl_certificate.pem \
smtpd_tls_key_file=$STORAGE_ROOT/ssl/ssl_private_key.pem \
smtpd_tls_dh1024_param_file=$STORAGE_ROOT/ssl/dh2048.pem \
smtpd_tls_protocols="!SSLv2,!SSLv3,!TLSv1,!TLSv1.1" \
smtpd_tls_protocols="!SSLv2,!SSLv3" \
smtpd_tls_ciphers=medium \
tls_medium_cipherlist=ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-RSA-CHACHA20-POLY1305:DHE-RSA-AES128-GCM-SHA256:DHE-RSA-AES256-GCM-SHA384:DHE-RSA-CHACHA20-POLY1305:ECDHE-ECDSA-AES128-SHA256:ECDHE-RSA-AES128-SHA256:ECDHE-ECDSA-AES128-SHA:ECDHE-RSA-AES128-SHA:ECDHE-ECDSA-AES256-SHA384:ECDHE-RSA-AES256-SHA384:ECDHE-ECDSA-AES256-SHA:ECDHE-RSA-AES256-SHA:DHE-RSA-AES128-SHA256:DHE-RSA-AES256-SHA256:AES128-GCM-SHA256:AES256-GCM-SHA384:AES128-SHA256:AES256-SHA256:AES128-SHA:AES256-SHA:DES-CBC3-SHA \
smtpd_tls_exclude_ciphers=aNULL,RC4 \
smtpd_tls_mandatory_protocols="!SSLv2,!SSLv3,!TLSv1,!TLSv1.1" \
smtpd_tls_ciphers=high \
smtpd_tls_mandatory_ciphers=high \
smtpd_tls_exclude_ciphers= \
tls_high_cipherlist=ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-RSA-CHACHA20-POLY1305:DHE-RSA-AES128-GCM-SHA256:DHE-RSA-AES256-GCM-SHA384 \
smtpd_tls_mandatory_exclude_ciphers=aNULL,DES,3DES,MD5,DES+MD5,RC4 \
tls_preempt_cipherlist=no \
smtpd_tls_received_header=yes
@ -150,7 +159,7 @@ tools/editconf.py /etc/postfix/main.cf \
# Since we'd rather have poor encryption than none at all, we use Mozilla's
# "Old" recommendations at https://ssl-config.mozilla.org/#server=postfix&server-version=3.3.0&config=old&openssl-version=1.1.1
# for opportunistic encryption but "Intermediate" recommendations when DANE
# is used (see next and above).
# is used (see next and above). The cipher lists are set above.
# DANE takes this a step further:
# Postfix queries DNS for the TLSA record on the destination MX host. If no TLSA records are found,
@ -166,8 +175,7 @@ tools/editconf.py /etc/postfix/main.cf \
tools/editconf.py /etc/postfix/main.cf \
smtp_tls_protocols=\!SSLv2,\!SSLv3 \
smtp_tls_ciphers=medium \
tls_medium_cipherlist=ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-RSA-CHACHA20-POLY1305:DHE-RSA-AES128-GCM-SHA256:DHE-RSA-AES256-GCM-SHA384:DHE-RSA-CHACHA20-POLY1305:ECDHE-ECDSA-AES128-SHA256:ECDHE-RSA-AES128-SHA256:ECDHE-ECDSA-AES128-SHA:ECDHE-RSA-AES128-SHA:ECDHE-ECDSA-AES256-SHA384:ECDHE-RSA-AES256-SHA384:ECDHE-ECDSA-AES256-SHA:ECDHE-RSA-AES256-SHA:DHE-RSA-AES128-SHA256:DHE-RSA-AES256-SHA256:AES128-GCM-SHA256:AES256-GCM-SHA384:AES128-SHA256:AES256-SHA256:AES128-SHA:AES256-SHA:DES-CBC3-SHA \
smtp_tls_exclude_ciphers= \
smtp_tls_exclude_ciphers=aNULL,RC4 \
smtp_tls_security_level=dane \
smtp_dns_support_level=dnssec \
smtp_tls_mandatory_protocols="!SSLv2,!SSLv3,!TLSv1,!TLSv1.1" \