README

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Multi-purpose security milter.

Guardian-milter is a Postfix/Sendmail milter for filtering various types of fake, phishing and spam emails. The milter executes highly crafted checks and marks incoming emails with a pass/fail header or rejects them during the SMTP dialogue.

Features

Add an Authentication-Results header
Copy failed emails to another email address
Reject failed emails during the SMTP conversation
Remove the name part of the From: header
Save failed emails in JSON format
Run regular expressions on the connection (IP/hostname)
Run regular expressions on the HELO/EHLO string
Run regular expressions on the envelope RCTP
Detect domain in the From name
Detect domain in the subject
Detect fake WeTransfer emails
Detect fake banking emails
Detect fake Maersk emails
Detect fake LinkedIn emails
Detect fake Louis Vuitton emails
Detect fake DHL emails
Detect fake USPS emails
Detect fake Chanel emails
Detect fake ELTA emails
Detect fake Facebook emails
Detect fake password expiration emails
Reject attachments with known problematic file extensions
AbuseIPDB integration
Block emails based on IP confidence score (AbuseIPDB)
Block emails by country of origin (AbuseIPDB)

Requirements

libMilterPHP
PHP 8.0, 8.1, 8.2, 8.3
iconv module
posix module
sockets module

Install with RPM packages

You may install guardian-milter via the copr repository, for Alma/Rocky/Oracle Enterprise Linux and Fedora, simply use:

dnf copr enable mksanthi/noumenia
dnf install guardian-milter

Install with Composer

You may install guardian-milter with composer, to get the latest version use the create-project command, the last dot is important because it tells composer to save the files in the current directory.

composer create-project noumenia/guardian-milter .

Configure postfix to use guardian-milter

Edit the /etc/postfix/main.cf file, add or modify the existing smtpd_milters parameter with the connection string for guardian-milter. For example:

smtpd_milters = inet:127.0.0.1:8895

How to use

If you installed via the RPM packages then a systemd service is already available and guardian-milter can be started with systemctl. By default, guardian-milter will read the configuration file /etc/gu-milter.ini and listen for connections at 127.0.0.1 port 8895.

systemctl --now enable guardian-milter

If you installed via composer or manually, then the gu-milter.ini file will be located in the same directory as the guardian-milter executable and can be specified with the --ini=... parameter. Below is the complete list of command-line parameters:

Usage: guardian-milter [OPTION]...

  -V,  --version             display version information only
  -h,  --help                display help about parameters
  -v,  --verbose             enable verbose output to stdout

  -u,  --user=[USER]         Effective user
  -g,  --group=[GROUP]       Effective group
  -p,  --pid=[FILE]          PID file
  -l,  --processlimit=[NUM]  Process limit
  -c,  --connection=[STRING] Connection string
  -a,  --autoload=[FILE]     LibMilterPHP autoloader (controller/common.inc.php)
  -i,  --ini=[FILE]          Configuration file (/etc/gu-milter.ini)

       --addHeader           Add Authentication-Results header with pass/fail information
       --reject              Reject failed emails
       --removeName          Remove From: header name part

 The connection string can be a UNIX socket or an IPv4/IPv6 address/port.
 UNIX Socket...: unix:/run/gu-milter/guardian-milter.sock
 Address/port..: inet:8895@127.0.0.1

noumenia / guardian-milter

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