--- /dev/null
+# HEADER_CHECKS(5) HEADER_CHECKS(5)
+#
+# NAME
+# header_checks - Postfix built-in header/body inspection
+#
+# SYNOPSIS
+# header_checks = pcre:/etc/postfix/header_checks
+# mime_header_checks = pcre:/etc/postfix/mime_header_checks
+# nested_header_checks = pcre:/etc/postfix/nested_header_checks
+# body_checks = pcre:/etc/postfix/body_checks
+#
+# postmap -fq "string" pcre:/etc/postfix/filename
+# postmap -fq - pcre:/etc/postfix/filename <inputfile
+#
+# DESCRIPTION
+# Postfix provides a simple built-in content inspection
+# mechanism that examines incoming mail one message header
+# or one message body line at a time. Each input is compared
+# against a list of patterns, and when a match is found the
+# corresponding action is executed. This feature is imple-
+# mented by the Postfix cleanup(8) server.
+#
+# For examples, see the EXAMPLES section at the end of this
+# manual page.
+#
+# Postfix header or body_checks are designed to stop a flood
+# of mail from worms or viruses; they do not decode attach-
+# ments, and they do not unzip archives. See the documents
+# referenced below in the README FILES section if you need
+# more sophisticated content analysis.
+#
+# Postfix supports four built-in content inspection classes:
+#
+# header_checks
+# These are applied to initial message headers
+# (except for the headers that are processed with
+# mime_header_checks).
+#
+# mime_header_checks (default: $header_checks)
+# These are applied to MIME related message headers
+# only.
+#
+# This feature is available in Postfix 2.0 and later.
+#
+# nested_header_checks (default: $header_checks)
+# These are applied to message headers of attached
+# email messages (except for the headers that are
+# processed with mime_header_checks).
+#
+# This feature is available in Postfix 2.0 and later.
+#
+# body_checks
+# These are applied to all other content, including
+# multi-part message boundaries.
+#
+# With Postfix versions before 2.0, all content after
+# the initial message headers is treated as body con-
+# tent.
+#
+# Note: message headers are examined one logical header at a
+# time, even when a message header spans multiple lines.
+# Body lines are always examined one line at a time.
+#
+# TABLE FORMAT
+# This document assumes that header and body_checks rules
+# are specified in the form of Postfix regular expression
+# lookup tables. Usually the best performance is obtained
+# with pcre (Perl Compatible Regular Expression) tables, but
+# the slower regexp (POSIX regular expressions) support is
+# more widely available. Use the command "postconf -m" to
+# find out what lookup table types your Postfix system sup-
+# ports.
+#
+# The general format of Postfix regular expression tables is
+# given below. For a discussion of specific pattern or
+# flags syntax, see pcre_table(5) or regexp_table(5),
+# respectively.
+#
+# /pattern/flags action
+# When pattern matches the input string, execute the
+# corresponding action. See below for a list of pos-
+# sible actions.
+#
+# !/pattern/flags action
+# When pattern does not match the input string, exe-
+# cute the corresponding action.
+#
+# if /pattern/flags
+#
+# endif Match the input string against the patterns between
+# if and endif, if and only if the input string also
+# matches pattern. The if..endif can nest.
+#
+# Note: do not prepend whitespace to patterns inside
+# if..endif.
+#
+# if !/pattern/flags
+#
+# endif Match the input string against the patterns between
+# if and endif, if and only if the input string does
+# not match pattern. The if..endif can nest.
+#
+# blank lines and comments
+# Empty lines and whitespace-only lines are ignored,
+# as are lines whose first non-whitespace character
+# is a `#'.
+#
+# multi-line text
+# A pattern/action line starts with non-whitespace
+# text. A line that starts with whitespace continues
+# a logical line.
+#
+# TABLE SEARCH ORDER
+# For each line of message input, the patterns are applied
+# in the order as specified in the table. When a pattern is
+# found that matches the input line, the corresponding
+# action is executed and then the next input line is
+# inspected.
+#
+# TEXT SUBSTITUTION
+# Substitution of substrings from the matched expression
+# into the action string is possible using the conventional
+# Perl syntax ($1, $2, etc.). The macros in the result
+# string may need to be written as ${n} or $(n) if they
+# aren't followed by whitespace.
+#
+# Note: since negated patterns (those preceded by !) return
+# a result when the expression does not match, substitutions
+# are not available for negated patterns.
+#
+# ACTIONS
+# Action names are case insensitive. They are shown in upper
+# case for consistency with other Postfix documentation.
+#
+# DISCARD optional text...
+# Claim successful delivery and silently discard the
+# message. Log the optional text if specified, oth-
+# erwise log a generic message.
+#
+# Note: this action disables further header or
+# body_checks inspection of the current message and
+# affects all recipients.
+#
+# This feature is available in Postfix 2.0 and later.
+#
+# DUNNO Pretend that the input line did not match any pat-
+# tern, and inspect the next input line. This action
+# can be used to shorten the table search.
+#
+# For backwards compatibility reasons, Postfix also
+# accepts OK but it is (and always has been) treated
+# as DUNNO.
+#
+# This feature is available in Postfix 2.1 and later.
+#
+# FILTER transport:destination
+# Write a content filter request to the queue file
+# and inspect the next input line. After the com-
+# plete message is received it will be sent through
+# the specified external content filter. More infor-
+# mation about external content filters is in the
+# Postfix FILTER_README file.
+#
+# Note: this action overrides the main.cf con-
+# tent_filter setting, and affects all recipients of
+# the message. In the case that multiple FILTER
+# actions fire, only the last one is executed.
+#
+# This feature is available in Postfix 2.0 and later.
+#
+# HOLD optional text...
+# Arrange for the message to be placed on the hold
+# queue, and inspect the next input line. The mes-
+# sage remains on hold until someone either deletes
+# it or releases it for delivery. Log the optional
+# text if specified, otherwise log a generic message.
+#
+# Mail that is placed on hold can be examined with
+# the postcat(1) command, and can be destroyed or
+# released with the postsuper(1) command.
+#
+# Note: use "postsuper -r" to release mail that was
+# kept on hold for a significant fraction of $maxi-
+# mal_queue_lifetime or $bounce_queue_lifetime, or
+# longer.
+#
+# Note: this action affects all recipients of the
+# message.
+#
+# This feature is available in Postfix 2.0 and later.
+#
+# IGNORE Delete the current line from the input and inspect
+# the next input line.
+#
+# PREPEND text...
+# Prepend one line with the specified text and
+# inspect the next input line.
+#
+# Notes:
+#
+# o The prepended text is output on a separate
+# line, immediately before the input that
+# triggered the PREPEND action.
+#
+# o The prepended text is not considered part of
+# the input stream: it is not subject to
+# header/body checks or address rewriting, and
+# it does not affect the way that Postfix adds
+# missing message headers.
+#
+# o When prepending text before a message header
+# line, the prepended text must begin with a
+# valid message header label.
+#
+# o This action cannot be used to prepend multi-
+# line text.
+#
+# This feature is available in Postfix 2.1 and later.
+#
+# REDIRECT user@domain
+# Write a message redirection request to the queue
+# file and inspect the next input line. After the
+# message is queued, it will be sent to the specified
+# address instead of the intended recipient(s).
+#
+# Note: this action overrides the FILTER action, and
+# affects all recipients of the message. If multiple
+# REDIRECT actions fire, only the last one is exe-
+# cuted.
+#
+# This feature is available in Postfix 2.1 and later.
+#
+# REPLACE text...
+# Replace the current line with the specified text
+# and inspect the next input line.
+#
+# This feature is available in Postfix 2.2 and later.
+# The description below applies to Postfix 2.2.2 and
+# later.
+#
+# Notes:
+#
+# o When replacing a message header line, the
+# replacement text must begin with a valid
+# header label.
+#
+# o The replaced text remains part of the input
+# stream. Unlike the result from the PREPEND
+# action, a replaced message header may be
+# subject to address rewriting and may affect
+# the way that Postfix adds missing message
+# headers.
+#
+# REJECT optional text...
+# Reject the entire message. Reply with optional
+# text... when the optional text is specified, other-
+# wise reply with a generic error message.
+#
+# Note: this action disables further header or
+# body_checks inspection of the current message and
+# affects all recipients.
+#
+# WARN optional text...
+# Log a warning with the optional text... (or log a
+# generic message) and inspect the next input line.
+# This action is useful for debugging and for testing
+# a pattern before applying more drastic actions.
+#
+# BUGS
+# Many people overlook the main limitations of header and
+# body_checks rules. These rules operate on one logical
+# message header or one body line at a time, and a decision
+# made for one line is not carried over to the next line.
+# If text in the message body is encoded (RFC 2045) then the
+# rules have to specified for the encoded form. Likewise,
+# when message headers are encoded (RFC 2047) then the rules
+# need to be specified for the encoded form.
+#
+# Message headers added by the cleanup(8) daemon itself are
+# excluded from inspection. Examples of such message headers
+# are From:, To:, Message-ID:, Date:.
+#
+# Message headers deleted by the cleanup(8) daemon will be
+# examined before they are deleted. Examples are: Bcc:, Con-
+# tent-Length:, Return-Path:.
+#
+# CONFIGURATION PARAMETERS
+# body_checks
+# Lookup tables with content filter rules for message
+# body lines. These filters see one physical line at
+# a time, in chunks of at most $line_length_limit
+# bytes.
+#
+# body_checks_size_limit
+# The amount of content per message body segment
+# (attachment) that is subjected to $body_checks fil-
+# tering.
+#
+# header_checks
+#
+# mime_header_checks (default: $header_checks)
+#
+# nested_header_checks (default: $header_checks)
+# Lookup tables with content filter rules for message
+# header lines: respectively, these are applied to
+# the initial message headers (not including MIME
+# headers), to the MIME headers anywhere in the mes-
+# sage, and to the initial headers of attached mes-
+# sages.
+#
+# Note: these filters see one logical message header
+# at a time, even when a message header spans multi-
+# ple lines. Message headers that are longer than
+# $header_size_limit characters are truncated.
+#
+# disable_mime_input_processing
+# While receiving mail, give no special treatment to
+# MIME related message headers; all text after the
+# initial message headers is considered to be part of
+# the message body. This means that header_checks is
+# applied to all the initial message headers, and
+# that body_checks is applied to the remainder of the
+# message.
+#
+# Note: when used in this manner, body_checks will
+# process a multi-line message header one line at a
+# time.
+#
+# EXAMPLES
+# Header pattern to block attachments with bad file name
+# extensions.
+#
+# /etc/postfix/main.cf:
+# header_checks = regexp:/etc/postfix/header_checks
+#
+# /etc/postfix/header_checks:
+# /^content-(type|disposition):.*name[[:space:]]*=.*\.(exe|vbs)/
+# REJECT Bad attachment file name extension: $2
+#
+# Body pattern to stop a specific HTML browser vulnerability
+# exploit.
+#
+# /etc/postfix/main.cf:
+# body_checks = regexp:/etc/postfix/body_checks
+#
+# /etc/postfix/body_checks:
+# /^<iframe src=(3D)?cid:.* height=(3D)?0 width=(3D)?0>$/
+# REJECT IFRAME vulnerability exploit
+#
+# SEE ALSO
+# cleanup(8), canonicalize and enqueue Postfix message
+# pcre_table(5), format of PCRE lookup tables
+# regexp_table(5), format of POSIX regular expression tables
+# postconf(1), Postfix configuration utility
+# postmap(1), Postfix lookup table management
+# postsuper(1), Postfix janitor
+# postcat(1), show Postfix queue file contents
+# RFC 2045, base64 and quoted-printable encoding rules
+# RFC 2047, message header encoding for non-ASCII text
+#
+# README FILES
+# Use "postconf readme_directory" or "postconf html_direc-
+# tory" to locate this information.
+# DATABASE_README, Postfix lookup table overview
+# CONTENT_INSPECTION_README, Postfix content inspection overview
+# BUILTIN_FILTER_README, Postfix built-in content inspection
+# BACKSCATTER_README, blocking returned forged mail
+#
+# LICENSE
+# The Secure Mailer license must be distributed with this
+# software.
+#
+# AUTHOR(S)
+# Wietse Venema
+# IBM T.J. Watson Research
+# P.O. Box 704
+# Yorktown Heights, NY 10598, USA
+#
+# HEADER_CHECKS(5)
projects / people / pmueller / ipfire-2.x.git / blobdiff