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Last update : 2022/04/24

milter-blockdomain

1.  Introduction
2.  Copyright, License
3.  Download
4.  Install
5.  Prepare block domain list
6.  Start milter-blockdomain

1. Introduction

The milter-blockdomain is a simple milter written in C to maintain thousands of block domains in simple plain expression.

• Separate configuration file and white/grey/black domain list file.
• Domain list file is auto-loaded when it is updated. No restarting is required.
• Check FQDN of dns reverse lookup name, helo, envelope from and/or envelope recipient.
  One domain entry in the domain list is applied to them.
• Domain entry is a simple plain expression. No escape character of regular expression is required.
  Domain is checked exact matching or domain boundary suffix matching, as config settings.

It is a practical use that making use of both the milter-blockdomain and the milter-greylist.
The milter-greylist works for unsolved IP address, malformed HELO/EHLO, GeoIP, widely applied rule by regular expression, and/or S25R.
It is good that the milter-blockdomain handle undesirable domain which is allowed by auto-whitelist of the milter-greylist.
The milter-regex is also useful.

Equivalent block list expression

milter-blockdomain	example.com
milter-greylist	racl blacklist domain example.com racl blacklist helo /^(.+\.)?example\.com$/ racl blacklist from /@(.+\.)?example\.com>$/
milter-regex	connect /^(.+\.)?example\.com$/ie // and envrcpt /^<.*>$/ helo /^(.+\.)?example\.com$/ie and envrcpt /^<.*>$/ envfrom /@(.+\.)?example\.com>$/ie and envrcpt /^<.*>$/

2. Copyright, License

The "milter-blockdomain" is copyright 2016 by Takao Abe. All rights reserved.
This software is free software, you can use and redistribute it and/or modify it under the
terms of the GNU General Public License as published by the Free Software Foundation,
either version 3 of the License, or any later version.

3. Download

GitHub   https://github.com/t2750xurb/milter-blockdomain

4. Install

Determine path. You may change them as you like.

File or Dir	Path	Related files which specifies this path.
Exec file	/usr/local/sbin/milter-blockdomain	Start script ( ex. /etc/rc.d/rc.milter-blockdomain )
Config file	/etc/mail/milter-blockdomain.conf	Start script ( ex. /etc/rc.d/rc.milter-blockdomain )
Socket file	/var/spool/milter/milter-blockdomain.sock	Config file ( Keyword: socket ) sendmail.mc ( Keyword: INPUT_MAIL_FILTER )
PID file	/var/run/milter-blockdomain.pid	Config file ( Keyword: pidFile )
Domain list files	/var/lib/milter-blockdomain/*	Config file ( Keyword: whitelist, blacklist, greylist )

Build and create directory

$ cd /tmp

$ tar jxf milter-blockdomain-M.NN.tar.bz2

$ cd milter-blockdomain-M.NN

$ ./configure --sysconfdir=/etc/mail

$ make

$ su
Password: **********

# make install

# mkdir /var/lib/milter-blockdomain

# mkdir /var/spool/milter

# chown smmsp:smmsp /var/spool/milter

# chmod o-rwx /var/spool/milter

Add "INPUT_MAIL_FILTER" to sendmail.mc

INPUT_MAIL_FILTER(`milter-blockdomain',`S=local:/var/spool/milter/milter-blockdomain.sock, F=, T=S:1m;R:1m')dnl

Generate sendmail.cf from sendmail.mc

Save current sendmail.cf as a backup.
# cp -p /etc/mail/sendmail.cf /etc/mail/sendmail.cf-yyyymmdd-hhmm

Change working directory
# cd /usr/share/sendmail/cf/cf

Generate sendmail.cf from sendmail.mc
# m4 /etc/mail/sendmail.mc | cat -s > /etc/mail/sendmail.cf

5. Prepare block domain list

If you don't have any block domain list at this time, just create empty file.

$ touch /var/lib/milter-blockdomain/xxxxxxxxxx.txt

6. Start milter-blockdomain

milter-blockdomain [-c config-file-path] [-d] [-s] [-t Interval] [-v]

-c

Specify the config file path, if the config file is other than /etc/mail/milter-blockdomain.conf.

-d

Debug mode, Non-daemon.

-s

Output Statistics count to syslog hourly. Default: Daily.

-t

Minimum domain list file update check interval. ( Seconds )

-v

Display version number.

# /usr/local/sbin/milter-blockdomain

If the config file is other than /etc/mail/milter-blockdomain.conf
# /usr/local/sbin/milter-blockdomain -c config-file-path

Contact, Bug report

  or  

Config file sample

# milter-blockdomain.conf

########################################
# user
# Mandatory, No default

user    smmsp

########################################
# socket
# Mandatory, No default
# Correspond with INPUT_MAIL_FILTER of sendmail.mc

socket  /var/spool/milter/milter-blockdomain.sock

########################################
# pidFile
# Mandatory, No default

pidFile /var/run/milter-blockdomain.pid

########################################
# checkConnect, checkHelo, checkEnvFrom, checkEnvRcpt
# 0 : Not checked
# 1 : Checked  ( Default )

checkConnect = 1
checkMacro_  = 1
checkHelo    = 1
checkEnvFrom = 1
checkEnvRcpt = 0

########################################
# checkOnAndAfter
# 0 : Check on and after connect
# 1 : Check on and after helo
# 2 : Check on and after envfrom
# 3 : Check on and after envrcpt ( Default )
# 4 : Check on and after header

checkOnAndAfter = 3

########################################
# Message

messageTempfail "Refused connection temporarily. Be patient."
messageReject   "Refused connection by site policy."

########################################
# Syslog facility name
# daemon, mail, user, local0 to local7

syslogFacility  = mail

########################################
# Syslog priority debug
# 0 : Do not write syslog priority=debug ( Default )
# 1 : Write syslog priority=debug

syslogDebug  = 0

########################################
# Subdomain
# 0 : Exact domain matching
# 1 : Subdomain matching ( Domain boundary )  ( Default )

Subdomain = 1

########################################
# whitelist, blacklist, greylist
# Max 8 files
# First match determine the result, accpet/reject/tempfail.
# Insensitive lower/upper case letter.

whitelist /var/lib/milter-blockdomain/whitelist.txt
blacklist /var/lib/milter-blockdomain/blacklist.txt
greylist  /var/lib/milter-blockdomain/greylist.txt

########################################
# DO NOT USE THIS PARAMETER
# testMode
# 0 : Check ( Default )
# 1 : Logging only ( Alway "Not listed" result )

#testMode = 0

########################################
# DO NOT USE THESE PARAMETERS
# debugConfigFunction, debugCheckFunction
# 0 : Disable debug log ( Default )
# 1 : Enable debug log

#debugConfigFunction = 0
#debugCheckFunction  = 0

Useful website

milter-greylist

http://hcpnet.free.fr/milter-greylist/

milter-regex

http://www.benzedrine.cx/milter-regex.html

milter-geoip

http://flatray.com/geoip/sendmail-milter.html

S25R Anti-spam technology ( Selective SMTP Rejection )

http://www.gabacho-net.jp/en/anti-spam/

http://www.fitserv.co.jp/ http://www.fitserv.jp/blockdomain/

Copyright (C) 2016, Takao Abe. All rights reserved.