# Copyright (C) 2019 Ian Kelling
# SPDX-License-Identifier: AGPL-3.0-or-later
-# todo: sandbox / harden exim:
-# 1. stop it from running as root. how?
-# https://www.exim.org/exim-html-current/doc/html/spec_html/ch-security_considerations.html
-# * avoid using .forward files, remove that router
-# * set deliver_drop_privilege
-# * set user to run as Debian-exim in systemd
-# * set port to something like 2500, and forward 25 to 2500 with iptables. same for 587.
-# https://superuser.com/questions/710253/allow-non-root-process-to-bind-to-port-80-and-443/1334552#1334552
-# * consider whether other routers like postmaster need modification / removal.
-# 2. restrict its filesystem access from within systemd
-
# todo: harden dovecot. need to do some research. one way is for it to only listen on a wireguard vpn interface, so only clients that are on the vpn can access it.
# todo: consider hardening cups listening on 0.0.0.0
# todo: stop/disable local apache, and rpc.mountd, and kdeconnect when not in use.
# todo: emailing info@amnimal.ninja produces a bounce, user doesn't exist
# instead of a simple rejection like it should.
-# todo: auto restart of je on checkrestart
-
# todo: run mailping test after running, or otherwise
# clear out terminal alert
[[ $EUID == 0 ]] || exec sudo -E "${BASH_SOURCE[0]}" "$@"
-
+# note, this is hardcoded in /etc/exim4/conf.d/main/000_local
u=$(id -nu 1000)
i() { # install file
local tmp tmpdir dest="$1"
local base="${dest##*/}"
- mkdir -p ${dest%/*}
+ local dir="${dest%/*}"
+ if [[ $dir != "$base" ]]; then
+ mkdir -p ${dest%/*}
+ fi
ir=false # i result
tmpdir=$(mktemp -d)
cat >$tmpdir/"$base"
# * Install universal packages
-# installs epanicclean
+# installs epanicclean iptables-exim ip6tables-exim
/a/bin/ds/install-my-scripts
if [[ $(debian-codename-compat) == bionic ]]; then
# note: pyzor debian readme says you need to run some initialization command
# but its outdated.
-pi spf-tools-perl p0f postgrey pyzor razor jq moreutils certbot
+pi spf-tools-perl p0f postgrey pyzor razor jq moreutils certbot fail2ban
# bad packages that sometimes get automatically installed
pu openresolv resolvconf
After=network.target mailnn.service
JoinsNamespaceOf=mailnn.service
BindsTo=mailnn.service
+StartLimitIntervalSec=0
[Service]
PrivateNetwork=true
# i dont think we need any of these, but it doesnt hurt to stay consistent
BindPaths=$bindpaths
+
+Restart=on-failure
+RestartSec=20
EOF
;;
esac
--deploy-hook /a/bin/ds/le-exim-deploy -d $wghost
fi
+# * fail2ban
+
+# todo: test that these configs actually work, eg run
+# s iptables-exim -S
+# and see someone is banned.
+
+sed 's/^ *before *= *iptables-common.conf/before = iptables-common-exim.conf/' \
+ /etc/fail2ban/action.d/iptables-multiport.conf| i /etc/fail2ban/action.d/iptables-exim.conf
+i /etc/fail2ban/action.d/iptables-common-exim.conf <<'EOF'
+# iank: same as iptables-common, except iptables is iptables-exim, ip6tables is ip6tables-exim
+
+# Fail2Ban configuration file
+#
+# Author: Daniel Black
+#
+# This is a included configuration file and includes the definitions for the iptables
+# used in all iptables based actions by default.
+#
+# The user can override the defaults in iptables-common.local
+#
+# Modified: Alexander Koeppe <format_c@online.de>, Serg G. Brester <serg.brester@sebres.de>
+# made config file IPv6 capable (see new section Init?family=inet6)
+
+[INCLUDES]
+
+after = iptables-blocktype.local
+ iptables-common.local
+# iptables-blocktype.local is obsolete
+
+[Definition]
+
+# Option: actionflush
+# Notes.: command executed once to flush IPS, by shutdown (resp. by stop of the jail or this action)
+# Values: CMD
+#
+actionflush = <iptables> -F f2b-<name>
+
+
+[Init]
+
+# Option: chain
+# Notes specifies the iptables chain to which the Fail2Ban rules should be
+# added
+# Values: STRING Default: INPUT
+chain = INPUT
+
+# Default name of the chain
+#
+name = default
+
+# Option: port
+# Notes.: specifies port to monitor
+# Values: [ NUM | STRING ] Default:
+#
+port = ssh
+
+# Option: protocol
+# Notes.: internally used by config reader for interpolations.
+# Values: [ tcp | udp | icmp | all ] Default: tcp
+#
+protocol = tcp
+
+# Option: blocktype
+# Note: This is what the action does with rules. This can be any jump target
+# as per the iptables man page (section 8). Common values are DROP
+# REJECT, REJECT --reject-with icmp-port-unreachable
+# Values: STRING
+blocktype = REJECT --reject-with icmp-port-unreachable
+
+# Option: returntype
+# Note: This is the default rule on "actionstart". This should be RETURN
+# in all (blocking) actions, except REJECT in allowing actions.
+# Values: STRING
+returntype = RETURN
+
+# Option: lockingopt
+# Notes.: Option was introduced to iptables to prevent multiple instances from
+# running concurrently and causing irratic behavior. -w was introduced
+# in iptables 1.4.20, so might be absent on older systems
+# See https://github.com/fail2ban/fail2ban/issues/1122
+# Values: STRING
+lockingopt = -w
+
+# Option: iptables
+# Notes.: Actual command to be executed, including common to all calls options
+# Values: STRING
+iptables = /usr/local/bin/iptables-exim <lockingopt>
+
+
+[Init?family=inet6]
+
+# Option: blocktype (ipv6)
+# Note: This is what the action does with rules. This can be any jump target
+# as per the iptables man page (section 8). Common values are DROP
+# REJECT, REJECT --reject-with icmp6-port-unreachable
+# Values: STRING
+blocktype = REJECT --reject-with icmp6-port-unreachable
+
+# Option: iptables (ipv6)
+# Notes.: Actual command to be executed, including common to all calls options
+# Values: STRING
+iptables = /usr/local/bin/ip6tables-exim <lockingopt>
+EOF
+
+i /etc/fail2ban/jail.d/exim.local <<'EOF'
+[exim]
+enabled = true
+port = 25,587
+filter = exim
+banaction = iptables-exim
+EOF
+if $ir; then
+ m systemctl restart fail2ban
+fi
+
# * common exim4 config
${files[@]} /etc/exim4
fi
-# by default, only 10 days of logs are kept. increase that.
-m sed -ri 's/^(\s*rotate\s).*/\11000/' /etc/logrotate.d/exim4-base
-
+# By default, only 10 days of logs are kept. increase that.
+# And dont compress, I look back at logs too often and
+# dont need the annoyance of decompressing them all the time.
+m sed -ri '/^\s*compress\s*$/d;s/^(\s*rotate\s).*/\11000/' /etc/logrotate.d/exim4-base
+files=(/var/log/exim4/*.gz)
+if (( ${#files[@]} )); then
+ gunzip ${files[@]}
+fi
-## https://blog.dhampir.no/content/make-exim4-on-debian-respect-forward-and-etcaliases-when-using-a-smarthost
-# i only need .forwards, so just doing that one.
-cd /etc/exim4/conf.d/router
-b=userforward_higher_priority
-# replace the router name so it is unique
-sed -r s/^\\S+:/$b:/ 600_exim4-config_userforward >175_$b
+## disabled. not using .forward files, but this is still interesting
+## for reference.
+# ## https://blog.dhampir.no/content/make-exim4-on-debian-respect-forward-and-etcaliases-when-using-a-smarthost
+# # i only need .forwards, so just doing that one.
+# cd /etc/exim4/conf.d/router
+# b=userforward_higher_priority
+# # replace the router name so it is unique
+# sed -r s/^\\S+:/$b:/ 600_exim4-config_userforward >175_$b
+rm -fv /etc/exim4/conf.d/router/175_userforward_higher_priority
# todo, consider 'separate' in etc/exim4.conf, could it help on busy systems?
rm -vf /etc/exim4/conf.d/main/000_localmacros # old filename
-cat >/etc/exim4/conf.d/main/000_local <<EOF
+
+# separate file so without quoted EOF for convenience
+cat >/etc/exim4/conf.d/main/000_local2 <<EOF
+# normally empty, I set this so I can set the envelope address
+# when doing mail redelivery to invoke filters. Also allows
+# me exiqgrep and stuff.
+MAIN_TRUSTED_GROUPS = $u
+EOF
+
+cat >/etc/exim4/conf.d/main/000_local <<'EOF'
MAIN_TLS_ENABLE = true
# require tls connections for all smarthosts
# Based on spec, seems like a good idea to be nice.
smtp_return_error_details = true
-# normally empty, I set this so I can set the envelope address
-# when doing mail redelivery to invoke filters. Also allows
-# me exiqgrep and stuff.
-MAIN_TRUSTED_GROUPS = $u
-
# default is 10. when exim has been down for a bit, fsf mailserver
# will do a big send in one connection, then exim decides to put
# the messages in the queue instead of delivering them, to avoid
# There could be some circumstance when the
# from: isnt our domain, but the envelope sender is
# and so still want to sign, but I cant think of any case.
-DKIM_DOMAIN = \${lc:\${domain:\$rh_from:}}
+DKIM_DOMAIN = ${lc:${domain:$rh_from:}}
# The file is based on the outgoing domain-name in the from-header.
# sign if key exists
-DKIM_PRIVATE_KEY = \${if exists{/etc/exim4/\${dkim_domain}-private.pem} {/etc/exim4/\${dkim_domain}-private.pem}}
+DKIM_PRIVATE_KEY = ${if exists{/etc/exim4/${dkim_domain}-private.pem} {/etc/exim4/${dkim_domain}-private.pem}}
# most of the ones that gmail seems to use.
# Exim has horrible default of signing unincluded
85.119.82.128 ; 2001:ba8:1f1:f09d::2 ; \\
# fsf_mit_net fsf_mit_net_ip6 fsf_net fsf_net_ip6 fsf_office_net
18.4.89.0/24 ; 2603:3005:71a:2e00::/64 ; 209.51.188.0/24 ; 2001:470:142::/48 ; 74.94.156.208/28
+
+
+# this is the default delay_warning_condition, plus matching on local_domains.
+# If I have some problem with my local system that causes delayed delivery,
+# I dont want to send warnings out to non-local domains.
+delay_warning_condition = ${if or {\
+ { !eq{$h_list-id:$h_list-post:$h_list-subscribe:}{} }\
+ { match{$h_precedence:}{(?i)bulk|list|junk} }\
+ { match{$h_auto-submitted:}{(?i)auto-generated|auto-replied} }\
+ { match_domain{$domain}{+local_domains} }\
+ } {no}{yes}}
+
+
EOF
rm -fv /etc/exim4/rcpt_local_acl # old path
EOF
-i /etc/exim4/conf.d/router/900_exim4-config_local_user <<EOF
+i /etc/exim4/conf.d/router/900_exim4-config_local_user <<'EOF'
### router/900_exim4-config_local_user
#################################
# This router matches local user mailboxes. If the router fails, the error
# message is "Unknown user".
local_user:
- debug_print = "R: local_user for \$local_part@\$domain"
+ debug_print = "R: local_user for $local_part@$domain"
driver = accept
domains = +local_domains
# ian: default file except where mentioned.
break
fi
done
- for f in /p/c/subdir_files/sieve/*sieve /a/c/subdir_files/sieve/*sieve; do
- m sudo -u $u /a/exe/lnf -T $f $uhome/sieve/${f##*/}
+ for f in /p/c/subdir_files/sieve/*sieve /a/bin/ds/subdir_files/sieve/*sieve; do
+ m sudo -u $u /a/exe/lnf -v -T $f $uhome/sieve/${f##*/}
done
# https://wiki.dovecot.org/SSL/DovecotConfiguration
ssl_key = </etc/exim4/exim.key
EOF
fi
- cat <<EOF
+ cat <<'EOF'
# https://ssl-config.mozilla.org
ssl = required
# this is the same as the certbot list, in my cert cronjob, I check if that has changed upstream.
protocol lmtp {
#per https://wiki2.dovecot.org/Pigeonhole/Sieve/Configuration
-# default is just \$mail_plugins
- mail_plugins = \$mail_plugins sieve
+# default is just $mail_plugins
+ mail_plugins = $mail_plugins sieve
}
EOF
if dpkg --compare-versions $(dpkg-query -f='${Version}\n' --show dovecot-core) ge 1:2.3; then
m chown -R www-data.www-data $rctmpdir /m/rc
m chmod 750 $rctmpdir
# Ensure the log file monitored by fail2ban exists, or else fail2ban can't start.
- # todo: setup fail2ban
# todo: check for other mailinabox things
m sudo -u www-data touch $rclogdir/errors.log
fi
-# ** auth
+# ** exim: auth
case $HOSTNAME in
bk|je)
EOF
fi
-# ** main daemon use non-default config file
+# ** exim: main daemon use non-default config file
case $HOSTNAME in
bk|$MAIL_HOST)
# to see the default comments in /etc/default/exim4:
QUEUEINTERVAL='30m'
COMMONOPTIONS='-C /etc/exim4/my.conf'
UPEX4OPTS='-o /etc/exim4/my.conf'
-#E4BCD_PANICLOG_NOISE='malware acl condition: clamd /var/run/clamav/clamd\.ctl : unable to connect to UNIX socket'
+#E4BCD_PANICLOG_NOISE='exim user lost privilege for using -C option'
EOF
+ chown Debian-exim:Debian-exim /usr/sbin/exim4
+ # needs guid set in order to become Debian-exim
+ chmod g+s,u+s /usr/sbin/exim4
i /etc/exim4/trusted_configs <<'EOF'
/etc/exim4/my.conf
EOF
;;
esac
+# ** exim non-root
+
case $HOSTNAME in
+ bk|je|li)
+ # no reason to expect it to ever be there.
+ rm -fv /etc/systemd/system/exim4.service.d/nonroot.conf
+ ;;
+ *)
+ i /etc/systemd/system/exim4.service.d/nonroot.conf <<'EOF'
+[Service]
+# see 56.2 Root privilege in exim spec
+AmbientCapabilities=CAP_NET_BIND_SERVICE
+# https://www.redhat.com/sysadmin/mastering-systemd
+# things that seem good and reasonabl.e
+PrivateTmp=yes
+ProtectHome=yes
+# note, in t10 systemd, if one of these is an sshfs mountpoint,
+# this whole setting doesnt work. tried it with a newer systemd 250 though
+# an nspawn, and it worked there.
+InaccessiblePaths=d m media mnt nocow o p q
+NoNewPrivileges=yes
+ProtectSystem=yes
+
+# when we get newer systemd
+#ProtectDevices=yes
+EOF
+ i /etc/exim4/conf.d/main/000_local-noroot <<'EOF'
+# see 56.2 Root privilege in exim spec
+deliver_drop_privilege = true
+EOF
+ files=(
+ 300_exim4-config_real_local
+ 600_exim4-config_userforward
+ 700_exim4-config_procmail
+ 800_exim4-config_maildrop
+ mmm_mail4root
+ )
+ for f in ${files[@]}; do
+ echo "# iank: removed due to running nonroot"|i /etc/exim4/conf.d/router/$f
+ done
+ ;;
+esac
+
+case $HOSTNAME in
+
# ** $MAIL_HOST|bk|je)
$MAIL_HOST|bk|je)
user = $u
EOF
- i /etc/exim4/conf.d/router/870_backup_local <<EOF
+ i /etc/exim4/conf.d/router/870_backup_local <<'EOF'
### router/900_exim4-config_local_user
#################################
backup_local:
- debug_print = "R: local_user for \$local_part@\$domain"
+ debug_print = "R: local_user for $local_part@$domain"
driver = accept
domains = eximbackup.b8.nz
transport = backup_maildir
#5-59/5 * * * * root mailtest-check |& log-once -1 mailtest-check
#0 * * * * root mailtest-check slow |& log-once -1 mailtest-slow
*/5 * * * * root timeout 290 mailtest-check slow |& log-once -12 mailtest-check
+# if a bounce happened yesterday, dont let it slip through the cracks
+8 1 * * * root awk '$5 == "**"' /var/log/exim4/mainlog.1
EOF
m sudo rsync -ahhi --chown=root:root --chmod=0755 \
/b/ds/mailtest-check /b/ds/check-remote-mailqs /usr/local/bin/
iankelling.org / git / distro-setup / blobdiff