Even though SMTP (on port 25) is typically opportunistic and a MitM attack can't be prevented, we may as well only offer ciphers that provide some level of security. If a client is so old or misconfigured that it doesn't support newer ciphers, it should hopefully fall back to a non-TLS connection.
Postfix's default was basically anything goes (anonymous and 40-bit ciphers!). Google's MTA's only offer ciphers at 112 bits at greater, and this change approximates that with Postfix's "medium" setting.
Fixes#371
This disallows aNULL and other bad ciphers in the Postfix submission server.
I missed an option in 45e93f7dcc recommended by the blog post I was reading.
Fixes#389.
I added OpenDMARC's milter in fba4d4702e. But this started
setting Authentication-Results headers on outbound mail with failures. Not sure why it
fails at that point, but it shouldn't be set at all. The failure might cause recipients
to junk the mail. See #358.
This commit removes the milter from the SMTP submission (port 587) listener.
nginx/postfix use a new pre-generated dh2048.pem file. dovecot generates the bits on its own.
ssllabs.com reports that TLS_DHE ciphers went from 1024 to 2048 bits as expected. The ECDHE ciphers remain at 256 bits --- no idea what that really means. (This tests nginx only. I haven't tested postfix/dovecot.)
see https://discourse.mailinabox.email/t/fips-ready-for-ssl-dhec-key-exchange/76/3
As the scripts keep growing, it's time to split them up to
keep them understandable.
This splits mail.sh into mail-postfix.sh, mail-dovecot.sh,
and mail-users.sh, which has all of the user database-related
configurations shared by Dovecot and Postfix. Also from
spamassassin.sh the core sieve configuration is moved into
mail-dovecot.sh and the virtual transport setting is moved
into mail-postfix.sh.
Also revising one of the sed scripts in mail-dovecot to
not insert a new additional # at the start of a line each
time the script is run.
Joshua Tauberer