From: Christian Heller Date: Fri, 15 May 2020 20:05:28 +0000 (+0200) Subject: Add mail server setup scripting. X-Git-Url: https://plomlompom.com/repos/%7B%7B%20web_path%20%7D%7D/static/%7B%7Bdb.prefix%7D%7D/%7B%7Bprefix%7D%7D/index.html?a=commitdiff_plain;h=b427e539c34c181ee681c249d8ba564f0c0d1d87;p=config Add mail server setup scripting. --- diff --git a/buster/apt-mark/mail b/buster/apt-mark/mail new file mode 100644 index 0000000..0956960 --- /dev/null +++ b/buster/apt-mark/mail @@ -0,0 +1,15 @@ +# smtp server +postfix +# opendkim +opendkim +opendkim-tools +# for pingmail +mailutils +# ssl +certbot +# IMAPS +pwgen +dovecot-imapd +# sieve filtering +dovecot-lmtpd +dovecot-sieve diff --git a/buster/etc_files/mail/etc/dovecot/conf.d/99-lmtp-sieve-filtering.conf b/buster/etc_files/mail/etc/dovecot/conf.d/99-lmtp-sieve-filtering.conf new file mode 100644 index 0000000..eaf927b --- /dev/null +++ b/buster/etc_files/mail/etc/dovecot/conf.d/99-lmtp-sieve-filtering.conf @@ -0,0 +1,18 @@ +# This is only necessary when we use dovecot's LMTP mechanism to receive +# mail from postfix. +auth_username_format = %Ln + +# Add sieve filtering. +protocol lmtp { + mail_plugins = $mail_plugins sieve +} + +# We don't strictly need to provide a LMTP server to fetch mail from +# postfix, but we do if we want to do sophisticated stuff like sieve +# filtering on the way. +service lmtp { + inet_listener lmtp { + address = 127.0.0.1 + port = 2424 + } +} diff --git a/buster/etc_files/mail/etc/dovecot/conf.d/99-smtp-sasl.conf b/buster/etc_files/mail/etc/dovecot/conf.d/99-smtp-sasl.conf new file mode 100644 index 0000000..d076d63 --- /dev/null +++ b/buster/etc_files/mail/etc/dovecot/conf.d/99-smtp-sasl.conf @@ -0,0 +1,10 @@ +service auth { + unix_listener auth-userdb { + } + + unix_listener /var/spool/postfix/private/auth { + mode = 0660 + user = postfix + group = postfix + } +} diff --git a/buster/etc_files/mail/etc/nftables.conf b/buster/etc_files/mail/etc/nftables.conf new file mode 100755 index 0000000..747d214 --- /dev/null +++ b/buster/etc_files/mail/etc/nftables.conf @@ -0,0 +1,24 @@ +#!/usr/sbin/nft -f + +flush ruleset + +table inet filter { + chain input { + type filter hook input priority 0; policy drop; + iif lo accept comment "accept localhost traffic" + ct state invalid drop comment "drop invalid connections" + ct state established, related accept comment "accept traffic originated from us" + tcp dport 22 accept comment "accept SSH on default port" + tcp dport 25 accept comment "accept SMTP (allowing for STARTTLS); necessary for mail server to mail server banter, i.e. for receiving mails" + tcp dport 80 accept comment "accept HTTP; necessary for Certbot HTTP challenge" + tcp dport 465 accept comment "accept SMTPS; for mail user agent to mail server, i.e. for sending mails" + tcp dport 993 accept comment "accept IMAPS; for reading/downloading mails" + ip protocol icmp icmp type echo-request accept comment "accept ICMP for pinging" + } + chain forward { + type filter hook forward priority 0; policy drop; + } + chain output { + type filter hook output priority 0; policy accept; + } +} diff --git a/buster/other_files/dovecot.sieve b/buster/other_files/dovecot.sieve new file mode 100644 index 0000000..5346309 --- /dev/null +++ b/buster/other_files/dovecot.sieve @@ -0,0 +1,8 @@ +require ["fileinto"]; +require ["mailbox"]; +if address :is "from" "foo@bar.com" { + fileinto :create "foo"; +} +if address :is :domain "to" "example.com" { + fileinto :create "example.com"; +} diff --git a/buster/setup_scripts/setup_mail.sh b/buster/setup_scripts/setup_mail.sh new file mode 100755 index 0000000..9406bee --- /dev/null +++ b/buster/setup_scripts/setup_mail.sh @@ -0,0 +1,114 @@ +#!/bin/sh +set -e + +if [ "$#" -ne 1 ]; then + echo 'Need mail for letsencrypt.' + false +fi +mail="$1" + +config_tree_prefix="${HOME}/config/buster" +echo "postfix postfix/main_mailer_type string 'Internet Site'" | debconf-set-selections +echo "postfix postfix/mailname string $(hostname -f)" | debconf-set-selections +./install_for_target.sh mail +./copy_dirtree.sh "${config_tree_prefix}/etc_files" "" mail +nft -f /etc/nftables.conf + +# Set up letsencrypt certificate. +# TODO: Is it auto-renewed? +# TODO: Find out if/why this works despite firewall? +certbot certonly --standalone --agree-tos --no-eff-email -m "${mail}" -d "$(hostname -f)" + +# generate opendkim selector +selector=$(hostname)$(date +%Y%m%d) +#opendkim-genkey -D /etc/dkimkeys -s "${selector}" +opendkim-genkey -d "$(hostname -f)" -D /etc/dkimkeys -s "${selector}" + +# customize /etc/opendkim.conf +echo '' >> /etc/opendkim.conf +echo '# plomlompom customizations' >> /etc/opendkim.conf +echo "Domain $(hostname -f)" >> /etc/opendkim.conf +echo "KeyFile /etc/dkimkeys/${selector}.private" >> /etc/opendkim.conf +echo "Selector ${selector}" >> /etc/opendkim.conf +echo 'Socket inet:8892@localhost' >> /etc/opendkim.conf + +# customize /etc/postfix/main.cf +echo '' >> /etc/postfix/main.cf +echo '# opendkim milter' >> /etc/postfix/main.cf +echo 'non_smtpd_milters = inet:localhost:8892' >> /etc/postfix/main.cf +echo '' >> /etc/postfix/main.cf +echo '# TLS certs' +echo 'smtpd_tls_cert_file=/etc/letsencrypt/live/${myhostname}/fullchain.pem' >> /etc/postfix/main.cf +echo 'smtpd_tls_key_file=/etc/letsencrypt/live/${myhostname}/privkey.pem' >> /etc/postfix/main.cf + +# TODO: consider + +# Dovecot sieve filtering via LMTP +echo '' >> /etc/postfix/main.cf +echo '# transport mail to dovecot; not strictly needed, as even without this' >> /etc/postfix/main.cf +echo '# postfix will throw mail to /var/mail/USER to be found by dovecot for' >> /etc/postfix/main.cf +echo "# serving via IMAP etc.; but using dovecot's LMTP server for delivery" >> /etc/postfix/main.cf +echo '# allows us to do stuff like dovecot-side sieve filtering.' >> /etc/postfix/main.cf +echo 'mailbox_transport = lmtp:inet:127.0.0.1:2424' >> /etc/postfix/main.cf +cp "${config_tree_prefix}/other_files/dovecot.sieve" /home/plom/.dovecot.sieve +chown plom:plom /home/plom/.dovecot.sieve + +# To allow IMAPS access +echo "ssl_cert = /etc/dovecot/conf.d/99-ssl-certs.conf +echo "ssl_key = > /etc/dovecot/conf.d/99-ssl-certs.conf +password=$(pwgen -s 100 1) +#echo 'mail_privileged_group = mail' >> /etc/dovecot/conf.d/99-mail.conf +echo "plom:${password}" | chpasswd + +# To use Dovecot SASL for SMTP access. +echo '' >> /etc/postfix/main.cf +echo '# use dovecot SASL for SMTP access' >> /etc/postfix/main.cf +echo 'smtpd_sasl_type = dovecot' >> /etc/postfix/main.cf +echo 'smtpd_sasl_path = private/auth' >> /etc/postfix/main.cf +echo 'smtpd_sasl_auth_enable = yes' >> /etc/postfix/main.cf + +service opendkim restart +service postfix restart +service dovecot restart + +echo "To put into DNS:" +cat "/etc/dkimkeys/${selector}.txt" +echo "If subdomain, append .subdomain to _domainkeys!" +echo "Also ensure DMARC record of 'v=DMARC1; p=none; rua=mailto:plom+dmarc@plomlompom.com;' as TXT entry at _dmarc or, if subdomain, _dmarc.subdomain" +echo "Also ensure SPF record of 'v=spf1 mx -all' at @ or subdomain" +echo "Also ensure reverse DNS lookup for our IP points to $(hostname -f)" +echo "Also ensure MX record of priority 10 for @ or subdomain pointing to $(hostname -f)" +echo "IMAPS password for user plom is: ${password}" + +# todo just for proper mail /sending/: +# * figure out /etc/mailname ("used by the Mail Transfer Agent (i.e. mail server) to know its own hostname", "will contain the portion after the username and @ (at) sign for email addresses of users on the machine", "Postfix sets myorigin=/etc/mailname. Myorigin is appended (with an @) to any bare name in any address field. During (re)configure, if /etc/mailname exists, it is used as the default value for myorigin in debconf dialogs. Changing it from the default results in postinst rewriting /etc/mailname to the new value.") – figure out if it is actually used? +# * figure out /etc/postfix/main.cf +# - myorigin ("specifies the domain that appears in mail that is posted on this machine. The default is to use the local machine name, $myhostname, which defaults to the name of the machine. Unless you are running a really small site, you probably want to change that into $mydomain, which defaults to the parent domain of the machine name") +# - myhostname ("The internet hostname of this mail system. The default is to use the fully-qualified domain name (FQDN) from gethostname(), or to use the non-FQDN result from gethostname() and append ".$mydomain". $myhostname is used as a default value for many other configuration parameters.") +# - mydomain ("The internet domain name of this mail system. The default is to use $myhostname minus the first component, or "localdomain" (Postfix 2.3 and later). $mydomain is used as a default value for many other configuration parameters.") +# - relay_domains ("What destination domains (and subdomains thereof) this system will relay mail to") +# - mydestination ("The list of domains that are delivered via the $local_transport mail delivery transport.") +# * figure out /etc/postfix/master.cf (configures what postfix daemons run in what way?) +# * how to check IP safety +# https://talosintelligence.com/reputation_center/lookup?search=$IP +# http://www.anti-abuse.org/multi-rbl-check-results/?host= +# https://www.dnsbl.info/dnsbl-database-check.php +# note that none of these catch the IPs that gmx etc. reject + +# other stuff: +# * figure out /etc/aliases (maps whom what is sent to – just re-use old core.plomlompom.com one? – also, run newaliases to generate /etc/aliases.db) +# * more /etc/postfix/main.cf +# - smtpd_recipient_restrictions +# - smtpd_helo_restrictions +# - smtpd_client_restrictions +# +# for using SMTP server remotely: +# - SASL mechanism, may use dovecot for that (smtpd_sasl_type, smtpd_sasl_path) +# - see https://wiki2.dovecot.org/HowTo/PostfixAndDovecotSASL +# - SASL is not a protocol but an abstraction layer to some auth mechanism +# - SSL works on transport layer +# - wild guess: TLS/SSL is used to authenticate /the server/ to the client, while SASL is used to identify /the client/ to the server +# - then it should be possible to do SASL without TLS/STARTTLS first? (experiment) +# - the telnet test should offer AUTH then without doing STARTTLS first +# +# for receiving mails: make sure firewall opens SMTP port 25, and for STARTTLS to work need certificate installed (set in postfix/main.cf) – some providers only deliver via STARTTLS, i.e. GMail – this all only delivers mails to /var/mail/…, dovecot should do more then