153 lines
7.4 KiB
Bash
Executable File
153 lines
7.4 KiB
Bash
Executable File
#!/bin/bash
|
|
#
|
|
# Postfix (SMTP)
|
|
#
|
|
# Postfix handles the transmission of email between servers
|
|
# using the SMTP protocol. It is a Mail Transfer Agent (MTA).
|
|
#
|
|
# Postfix listens on port 25 (SMTP) for incoming mail from
|
|
# other servers on the Internet. It is responsible for very
|
|
# basic email filtering such as by IP address and greylisting,
|
|
# it checks that the destination address is valid, rewrites
|
|
# destinations according to aliases, and passses email on to
|
|
# another service for local mail delivery.
|
|
#
|
|
# The first hop in local mail delivery is to Spamassassin via
|
|
# LMTP. Spamassassin then passes mail over to Dovecot for
|
|
# storage in the user's mailbox.
|
|
#
|
|
# Postfix also listens on port 587 (SMTP+STARTLS) for
|
|
# connections from users who can authenticate and then sends
|
|
# their email out to the outside world. Postfix queries Dovecot
|
|
# to authenticate users.
|
|
#
|
|
# Address validation, alias rewriting, and user authentication
|
|
# is configured in a separate setup script mail-users.sh
|
|
# because of the overlap of this part with the Dovecot
|
|
# configuration.
|
|
|
|
source setup/functions.sh # load our functions
|
|
source /etc/mailinabox.conf # load global vars
|
|
|
|
# Install packages.
|
|
# python-libmilter is needed by our encryption milter.
|
|
|
|
apt_install postfix postgrey postfix-pcre
|
|
hide_output pip3 install git+https://github.com/mail-in-a-box/python-libmilter
|
|
|
|
# Basic Settings
|
|
|
|
# Have postfix listen on all network interfaces, set our name (the Debian default seems to be localhost),
|
|
# and set the name of the local machine to localhost for xxx@localhost mail (but I don't think this will have any effect because
|
|
# there is no true local mail delivery). Also set the banner (must have the hostname first, then anything).
|
|
tools/editconf.py /etc/postfix/main.cf \
|
|
inet_interfaces=all \
|
|
myhostname=$PRIMARY_HOSTNAME\
|
|
smtpd_banner="\$myhostname ESMTP Hi, I'm a Mail-in-a-Box (Ubuntu/Postfix; see https://github.com/joshdata/mailinabox)" \
|
|
mydestination=localhost
|
|
|
|
# Outgoing Mail
|
|
|
|
# Enable the 'submission' port 587 smtpd server and tweak its settings.
|
|
# a) Require the best ciphers for incoming connections per http://baldric.net/2013/12/07/tls-ciphers-in-postfix-and-dovecot/.
|
|
# but without affecting opportunistic TLS on incoming mail, which will allow any cipher (it's better than none).
|
|
# b) Give it a different name in syslog to distinguish it from the port 25 smtpd server.
|
|
# c) Add a new cleanup service specific to the submission service ('authclean')
|
|
# that filters out privacy-sensitive headers on mail being sent out by
|
|
# authenticated users.
|
|
# d) Create an alternative one running on port 10587 that requires that all recipients have findable
|
|
# OpenPGP keys. Encrypts the message for the recipients using a milter on port 882. The milter
|
|
# precedes the DKIM milter on 8891 so that the message isn't touched after DKIM signing. If the
|
|
# encryption milter isn't running, reject the message so we dont send anything in the clear.
|
|
tools/editconf.py /etc/postfix/master.cf -s -w \
|
|
"submission=inet n - - - - smtpd
|
|
-o syslog_name=postfix/submission
|
|
-o smtpd_tls_ciphers=high -o smtpd_tls_protocols=!SSLv2,!SSLv3
|
|
-o cleanup_service_name=authclean" \
|
|
"10587=inet n - - - - smtpd
|
|
-o syslog_name=postfix/submission-encrypted
|
|
-o smtpd_tls_ciphers=high -o smtpd_tls_protocols=!SSLv2,!SSLv3
|
|
-o cleanup_service_name=authclean
|
|
-o smtpd_milters=inet:127.0.0.1:8892,inet:127.0.0.1:8891 -o milter_default_action=reject" \
|
|
"authclean=unix n - - - 0 cleanup
|
|
-o header_checks=pcre:/etc/postfix/outgoing_mail_header_filters"
|
|
|
|
# Install the `outgoing_mail_header_filters` file required by the new 'authclean' service.
|
|
cp conf/postfix_outgoing_mail_header_filters /etc/postfix/outgoing_mail_header_filters
|
|
|
|
# Enable TLS on incoming 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.
|
|
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_received_header=yes
|
|
|
|
# When connecting to remote SMTP servers, prefer TLS and use DANE if available.
|
|
# Postfix queries for the TLSA record on the destination MX host. If no TLSA records are found,
|
|
# then opportunistic TLS is used. Otherwise the server certificate must match the TLSA records
|
|
# or else the mail bounces. TLSA also requires DNSSEC on the MX host. Postfix doesn't do DNSSEC
|
|
# itself but assumes the system's nameserver does and reports DNSSEC status. Thus this also
|
|
# relies on our local bind9 server being present and smtp_dns_support_level being set to dnssec
|
|
# to use it.
|
|
tools/editconf.py /etc/postfix/main.cf \
|
|
smtp_tls_security_level=dane \
|
|
smtp_dns_support_level=dnssec \
|
|
smtp_tls_loglevel=2
|
|
|
|
# Incoming Mail
|
|
|
|
# Pass any incoming mail over to a local delivery agent. Spamassassin
|
|
# will act as the LDA agent at first. It is listening on port 10025
|
|
# with LMTP. Spamassassin will pass the mail over to Dovecot after.
|
|
#
|
|
# In a basic setup we would pass mail directly to Dovecot like so:
|
|
# tools/editconf.py /etc/postfix/main.cf virtual_transport=lmtp:unix:private/dovecot-lmtp
|
|
#
|
|
tools/editconf.py /etc/postfix/main.cf virtual_transport=lmtp:[127.0.0.1]:10025
|
|
|
|
# Who can send outbound mail? The purpose of this is to prevent
|
|
# non-authenticated users from sending mail that requires being
|
|
# relayed elsewhere. We don't want to be an "open relay".
|
|
#
|
|
# permit_sasl_authenticated: Authenticated users (i.e. on port 587).
|
|
# permit_mynetworks: Mail that originates locally.
|
|
# reject_unauth_destination: No one else. (Permits mail whose destination is local and rejects other mail.)
|
|
tools/editconf.py /etc/postfix/main.cf \
|
|
smtpd_relay_restrictions=permit_sasl_authenticated,permit_mynetworks,reject_unauth_destination
|
|
|
|
# Who can send mail to us? Some basic filters.
|
|
#
|
|
# reject_non_fqdn_sender: Reject not-nice-looking return paths.
|
|
# reject_unknown_sender_domain: Reject return paths with invalid domains.
|
|
# reject_rhsbl_sender: Reject return paths that use blacklisted domains.
|
|
# permit_sasl_authenticated: Authenticated users (i.e. on port 587).
|
|
# permit_mynetworks: Mail that originates locally.
|
|
# reject_rbl_client: Reject connections from IP addresses blacklisted in zen.spamhaus.org
|
|
# check_policy_service: Apply greylisting using postgrey.
|
|
#
|
|
# Notes:
|
|
# permit_dnswl_client can pass through mail from whitelisted IP addresses, which would be good to put before greylisting
|
|
# so these IPs get mail delivered quickly. But when an IP is not listed in the permit_dnswl_client list (i.e. it is not
|
|
# whitelisted) then postfix does a DEFER_IF_REJECT, which results in all "unknown user" sorts of messages turning into
|
|
# "450 4.7.1 Client host rejected: Service unavailable". This is a retry code, so the mail doesn't properly bounce.
|
|
tools/editconf.py /etc/postfix/main.cf \
|
|
smtpd_sender_restrictions="reject_non_fqdn_sender,reject_unknown_sender_domain,reject_rhsbl_sender dbl.spamhaus.org" \
|
|
smtpd_recipient_restrictions=permit_sasl_authenticated,permit_mynetworks,"reject_rbl_client zen.spamhaus.org","check_policy_service inet:127.0.0.1:10023"
|
|
|
|
# Increase the message size limit from 10MB to 128MB.
|
|
tools/editconf.py /etc/postfix/main.cf \
|
|
message_size_limit=134217728
|
|
|
|
# Allow the two SMTP ports in the firewall.
|
|
|
|
ufw_allow smtp
|
|
ufw_allow submission
|
|
ufw_allow 10587
|
|
|
|
# Restart services
|
|
|
|
restart_service postfix
|