[Mimedefang] Disable filter on smtp-auth

Wesley M.A mimedefang at aise.re
Sun Jan 27 15:09:10 EST 2013


Hi,

I'm using OpenBSD-5.2, sendmail 8.14.5 and mimedefang 2.73p7
I just enable saslauthd on this mail server.
But when clients send emails using our MTA, their message are filtered 
and so they are like [SPAM]

Is there a way to disable this filter only for SMTP Auth ?

Thank you very much.



Here's my mimedefang-filter :

# -*- Perl -*-
#***********************************************************************
#
# mimedefang-filter
#
# Copyright (C) 2002 Roaring Penguin Software Inc.
#
# This program may be distributed under the terms of the GNU General
# Public License, Version 2, or (at your option) any later version.
#
# $Id$
#***********************************************************************

#***********************************************************************
# Set administrator's e-mail address here. The administrator receives
# quarantine messages and is listed as the contact for site-wide
# MIMEDefang policy. A good example would be 
'defang-admin at mydomain.com'
#***********************************************************************
$AdminAddress = 'postmaster at localhost';
$AdminName = "Postmaster";

#***********************************************************************
# Set the e-mail address from which MIMEDefang quarantine warnings and
# user notifications appear to come. A good example would be
# 'mimedefang at mydomain.com'. Make sure to have an alias for this
# address if you want replies to it to work.
#***********************************************************************
$DaemonAddress = 'postmaster at localhost';

#***********************************************************************
# If you set $AddWarningsInline to 1, then MIMEDefang tries *very* hard
# to add warnings directly in the message body (text or html) rather
# than adding a separate "WARNING.TXT" MIME part. If the message
# has no text or html part, then a separate MIME part is still used.
#***********************************************************************
$AddWarningsInline = 0;

#***********************************************************************
# To enable syslogging of virus and spam activity, add the following
# to the filter:
# md_graphdefang_log_enable();
# You may optionally provide a syslogging facility by passing an
# argument such as: md_graphdefang_log_enable('local4'); If you do 
this, be
# sure to setup the new syslog facility (probably in /etc/syslog.conf).
# An optional second argument causes a line of output to be produced
# for each recipient (if it is 1), or only a single summary line
# for all recipients (if it is 0.) The default is 1.
# Comment this line out to disable logging.
#***********************************************************************
md_graphdefang_log_enable('mail', 1);

#***********************************************************************
# Uncomment this to block messages with more than 50 parts. This will
# *NOT* work unless you're using Roaring Penguin's patched version
# of MIME tools, version MIME-tools-5.411a-RP-Patched-02 or later.
#
# WARNING: DO NOT SET THIS VARIABLE unless you're using at least
# MIME-tools-5.411a-RP-Patched-02; otherwise, your filter will fail.
#***********************************************************************
# $MaxMIMEParts = 50;

#***********************************************************************
# Uncomment to enable the clamd(8) anti-virus daemon.
#***********************************************************************
$Features{'Virus:CLAMD'} = 1;
$ClamdSock = "/tmp/clamd.socket";

#***********************************************************************
# Set various stupid things your mail client does below.
#***********************************************************************

# Set the next one if your mail client cannot handle multiple "inline"
# parts.
$Stupidity{"NoMultipleInlines"} = 0;

# Detect and load Perl modules
detect_and_load_perl_modules();

# This procedure returns true for entities with bad filenames.
sub filter_bad_filename {
my($entity) = @_;
my($bad_exts, $re);

# Bad extensions
$bad_exts = 
'(ade|adp|app|asd|asf|asx|bas|bat|chm|cmd|com|cpl|crt|dll|exe|fxp|hlp|hta|hto|inf|ini|ins|isp|jse?|lib|lnk|mdb|mde|msc|msi|msp|mst|ocx|pcd|pif|prg|reg|scr|sct|sh|shb|shs|sys|url|vb|vbe|vbs|vcs|vxd|wmd|wms|wmz|wsc|wsf|wsh|\{[^\}]+\})';

# Do not allow:
# - CLSIDs {foobarbaz}
# - bad extensions (possibly with trailing dots) at end
$re = '\.' . $bad_exts . '\.*$';

return 1 if (re_match($entity, $re));

# Look inside ZIP files
if (re_match($entity, '\.zip$') and
$Features{"Archive::Zip"}) {
my $bh = $entity->bodyhandle();
if (defined($bh)) {
my $path = $bh->path();
if (defined($path)) {
return re_match_in_zip_directory($path, $re);
}
}
}
return 0;
}

#***********************************************************************
# %PROCEDURE: filter_begin
# %ARGUMENTS:
# $entity -- the parsed MIME::Entity
# %RETURNS:
# Nothing
# %DESCRIPTION:
# Called just before e-mail parts are processed
#***********************************************************************
sub filter_begin {
my($entity) = @_;
# ALWAYS drop messages with suspicious chars in headers
if ($SuspiciousCharsInHeaders) {
md_graphdefang_log('suspicious_chars');
# action_quarantine_entire_message("Message quarantined because of 
suspicious characters in headers");
# Do NOT allow message to reach recipient(s)
return action_discard();
}

# Copy original message into work directory as an "mbox" file for
# virus-scanning
md_copy_orig_msg_to_work_dir_as_mbox_file();

# Scan for viruses if any virus-scanners are installed
my($code, $category, $action) = message_contains_virus();

# Lower level of paranoia - only looks for actual viruses
$FoundVirus = ($category eq "virus");

# Higher level of paranoia - takes care of "suspicious" objects
# $FoundVirus = ($action eq "quarantine");

if ($FoundVirus) {
md_graphdefang_log('virus', $VirusName, $RelayAddr);
md_syslog('warning', "Discarding because of virus $VirusName");
# Uncomment to copy the message to quarantine before discarding it.
# action_quarantine_entire_message();
return action_discard();
}

if ($action eq "tempfail") {
action_tempfail("Problem running virus-scanner");
md_syslog('warning', "Problem running virus scanner: code=$code, 
category=$category, action=$action");
}
}

#***********************************************************************
# %PROCEDURE: filter
# %ARGUMENTS:
# entity -- a Mime::Entity object (see MIME-tools documentation for 
details)
# fname -- the suggested filename, taken from the MIME 
Content-Disposition:
# header. If no filename was suggested, then fname is ""
# ext -- the file extension (everything from the last period in the 
name
# to the end of the name, including the period.)
# type -- the MIME type, taken from the Content-Type: header.
#
# NOTE: There are two likely and one unlikely place for a filename to
# appear in a MIME message: In Content-Disposition: filename, in
# Content-Type: name, and in Content-Description. If you are paranoid,
# you will use the re_match and re_match_ext functions, which return 
true
# if ANY of these possibilities match. re_match checks the whole name;
# re_match_ext checks the extension. See the sample filter below for 
usage.
# %RETURNS:
# Nothing
# %DESCRIPTION:
# This function is called once for each part of a MIME message.
# There are many action_*() routines which can decide the fate
# of each part; see the mimedefang-filter man page.
#***********************************************************************
sub filter {
my($entity, $fname, $ext, $type) = @_;

return if message_rejected(); # Avoid unnecessary work

# Block message/partial parts
if (lc($type) eq "message/partial") {
md_graphdefang_log('message/partial');
action_bounce("MIME type message/partial not accepted here");
return action_discard();
}

# Uncomment to enable bad extension filtering for MIME messages.
# if (filter_bad_filename($entity)) {
# md_graphdefang_log('bad_filename', $fname, $type);
# return action_drop_with_warning("An attachment named $fname was 
removed from this document as it\nconstituted a security hazard. If you 
require this document, please contact\nthe sender and arrange an 
alternate means of receiving it.\n");
# }

return action_accept();
}

#***********************************************************************
# %PROCEDURE: filter_multipart
# %ARGUMENTS:
# entity -- a Mime::Entity object (see MIME-tools documentation for 
details)
# fname -- the suggested filename, taken from the MIME 
Content-Disposition:
# header. If no filename was suggested, then fname is ""
# ext -- the file extension (everything from the last period in the 
name
# to the end of the name, including the period.)
# type -- the MIME type, taken from the Content-Type: header.
# %RETURNS:
# Nothing
# %DESCRIPTION:
# This is called for multipart "container" parts such as 
message/rfc822.
# You cannot replace the body (because multipart parts have no body),
# but you should check for bad filenames.
#***********************************************************************
sub filter_multipart {
my($entity, $fname, $ext, $type) = @_;

return if message_rejected(); # Avoid unnecessary work

# Uncomment to enable bad extension filtering for multipart messages.
# if (filter_bad_filename($entity)) {
# md_graphdefang_log('bad_filename', $fname, $type);
# action_notify_administrator("A MULTIPART attachment of type $type, 
named $fname was dropped.\n");
# return action_drop_with_warning("An attachment of type $type, named 
$fname was removed from this document as it\nconstituted a security 
hazard. If you require this document, please contact\nthe sender and 
arrange an alternate means of receiving it.\n");
# }

# Block message/partial parts
if (lc($type) eq "message/partial") {
md_graphdefang_log('message/partial');
action_bounce("MIME type message/partial not accepted here");
return;
}

return action_accept();
}


#***********************************************************************
# %PROCEDURE: defang_warning
# %ARGUMENTS:
# oldfname -- the old file name of an attachment
# fname -- the new "defanged" name
# %RETURNS:
# A warning message
# %DESCRIPTION:
# This function customizes the warning message when an attachment
# is defanged.
#***********************************************************************
sub defang_warning {
my($oldfname, $fname) = @_;
return
"An attachment named '$oldfname' was converted to '$fname'.\n" .
"To recover the file, right-click on the attachment and Save As\n" .
"'$oldfname'\n";
}

# If SpamAssassin found SPAM, append report. We do it as a separate
# attachment of type text/plain
sub filter_end {
my($entity) = @_;

# If you want quarantine reports, uncomment next line
# send_quarantine_notifications();

# IMPORTANT NOTE: YOU MUST CALL send_quarantine_notifications() AFTER
# ANY PARTS HAVE BEEN QUARANTINED. SO IF YOU MODIFY THIS FILTER TO
# QUARANTINE SPAM, REWORK THE LOGIC TO CALL 
send_quarantine_notifications()
# AT THE END!!!

# No sense doing any extra work
return if message_rejected();

# Spam checks if SpamAssassin is installed
if ($Features{"SpamAssassin"}) {
if (-s "./INPUTMSG" < 100*1024) {
# Only scan messages smaller than 100kB. Larger messages
# are extremely unlikely to be spam, and SpamAssassin is
# dreadfully slow on very large messages.
my($hits, $req, $names, $report) = spam_assassin_check();
my($score);
if ($hits < 40) {
$score = "*" x int($hits);
} else {
$score = "*" x 40;
}
# We add a header which looks like this:
# X-Spam-Score: 6.8 (******) NAME_OF_TEST,NAME_OF_TEST
# The number of asterisks in parens is the integer part
# of the spam score clamped to a maximum of 40.
# MUA filters can easily be written to trigger on a
# minimum number of asterisks...
if ($hits >= $req) {
action_change_header("X-Spam-Score", "$hits ($score) $names");
md_graphdefang_log('spam', $hits, $RelayAddr);

# If you find the SA report useful, add it, I guess...
action_add_part($entity, "text/plain", "-suggest",
"$report\n",
"SpamAssassinReport.txt", "inline");
} else {
# Delete any existing X-Spam-Score header?
action_delete_header("X-Spam-Score");
}
}
}

# I HATE HTML MAIL! If there's a multipart/alternative with both
# text/plain and text/html parts, nuke the text/html. Thanks for
# wasting our disk space and bandwidth...

# If you want to strip out HTML parts if there is a corresponding
# plain-text part, uncomment the next line.
# remove_redundant_html_parts($entity);

md_graphdefang_log('mail_in');

# Deal with malformed MIME.
# Some viruses produce malformed MIME messages that are misinterpreted
# by mail clients. They also might slip under the radar of MIMEDefang.
# If you are worried about this, you should canonicalize all
# e-mail by uncommenting the action_rebuild() line. This will
# force _all_ messages to be reconstructed as valid MIME. It will
# increase the load on your server, and might break messages produced
# by marginal software. Your call.

# action_rebuild();

# Uncomment to prepend '[SPAM] ' to the subject of X-Spam-Status tagged 
mails.
if (spam_assassin_is_spam()) { action_change_header("Subject", "[SPAM] 
$Subject"); }

# If the file(s) /etc/mail/disclaimer.txt and/or 
/etc/mail/disclaimer.html
# are present, they will be appended to all outgoing mails.
# Modify 192.168.1 to match your local network(s).
if ($RelayAddr =~ /192\.168\.0\./ or $RelayAddr eq "127.0.0.1") {
my $disclaimer = '/etc/mail/disclaimer.txt';
my $disclaimer_html = '/etc/mail/disclaimer.html';

if (-e $disclaimer) {
open FILE, "<$disclaimer";
my $text_boilerplate = do { local $/; <FILE> };
append_text_boilerplate($entity, $text_boilerplate, 0);
}
if (-e $disclaimer_html) {
open FILE, "<$disclaimer_html";
my $html_boilerplate = do { local $/; <FILE> };
append_html_boilerplate($entity, $html_boilerplate, 0);
}
}
}

# Uncomment to disable filtering mails sent from localhost
# (mimedefang(8) must be stated with the `-r' flag).
#sub filter_relay {
# my ($ip, $name) = @_;
# if ($ip eq '127.0.0.1') {
# return ('ACCEPT_AND_NO_MORE_FILTERING', "ok");
# }

# return ('CONTINUE', "ok");
#}

# DO NOT delete the next line, or Perl will complain.
1;



--
Wesley


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