REGEXP_TABLE(5) REGEXP_TABLE(5)
NAME
regexp_table - format of Postfix regular expression tables
SYNOPSIS
postmap -q "string" regexp:/etc/postfix/filename postmap -q - regexp:/etc/postfix/filename <inputfile
DESCRIPTION
The Postfix mail system uses optional tables for address rewriting, mail routing, or access control. These tables are usually in dbm or db format. Alternatively, lookup tables can be specified in POSIX regular expres- sion form. In this case, each input is compared against a list of pat- terns. When a match is found, the corresponding result is returned and the search is terminated. To find out what types of lookup tables your Postfix system supports use the "postconf -m" command. To test lookup tables, use the "postmap -q" command as described in the SYNOPSIS above.
COMPATIBILITY
With Postfix version 2.2 and earlier specify "postmap -fq" to query a table that contains case sensitive patterns. Patterns are case insensi- tive by default.
TABLE FORMAT
The general form of a Postfix regular expression table is: /pattern/flags result When pattern matches the input string, use the corresponding result value. !/pattern/flags result When pattern does not match the input string, use the corre- sponding result value. if /pattern/flags endif Match the input string against the patterns between if and endif, if and only if that same input string also matches pat- tern. The if..endif can nest. Note: do not prepend whitespace to patterns inside if..endif. This feature is available in Postfix 2.1 and later. if !/pattern/flags endif Match the input string against the patterns between if and endif, if and only if that same input string does not match pat- tern. The if..endif can nest. Note: do not prepend whitespace to patterns inside if..endif. This feature is available in Postfix 2.1 and later. 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 logical line starts with non-whitespace text. A line that starts with whitespace continues a logical line. Each pattern is a POSIX regular expression enclosed by a pair of delim- iters. The regular expression syntax is documented in re_format(7) with 4.4BSD, in regex(5) with Solaris, and in regex(7) with Linux. Other systems may use other document names. The expression delimiter can be any character, except whitespace or characters that have special meaning (traditionally the forward slash is used). The regular expression can contain whitespace. By default, matching is case-insensitive, and newlines are not treated as special characters. The behavior is controlled by flags, which are toggled by appending one or more of the following characters after the pattern: i (default: on) Toggles the case sensitivity flag. By default, matching is case insensitive. x (default: on) Toggles the extended expression syntax flag. By default, support for extended expression syntax is enabled. m (default: off) Toggle the multi-line mode flag. When this flag is on, the ^ and $ metacharacters match immediately after and immediately before a newline character, respectively, in addition to matching at the start and end of the input string.
TABLE SEARCH ORDER
Patterns are applied in the order as specified in the table, until a pattern is found that matches the input string. Each pattern is applied to the entire input string. Depending on the application, that string is an entire client hostname, an entire client IP address, or an entire mail address. Thus, no parent domain or par- ent network search is done, and user@domain mail addresses are not bro- ken up into their user and domain constituent parts, nor is user+foo broken up into user and foo.
TEXT SUBSTITUTION
Substitution of substrings from the matched expression into the result string is possible using $1, $2, etc.; specify $$ to produce a $ char- acter as output. The macros in the result string may need to be writ- ten as ${n} or $(n) if they aren't followed by whitespace. Note: since negated patterns (those preceded by !) return a result when the expression does not match, substitutions are not available for negated patterns.
EXAMPLE SMTPD ACCESS MAP
# Disallow sender-specified routing. This is a must if you relay mail # for other domains. /[%!@].*[%!@]/ 550 Sender-specified routing rejected # Postmaster is OK, that way they can talk to us about how to fix # their problem. /^postmaster@/ OK # Protect your outgoing majordomo exploders if !/^owner-/ /^(.*)-outgoing@(.*)$/ 550 Use ${1}@${2} instead endif
EXAMPLE HEADER FILTER MAP
# These were once common in junk mail. /^Subject: make money fast/ REJECT /^To: friend@public\.com/ REJECT
EXAMPLE BODY FILTER MAP
# First skip over base 64 encoded text to save CPU cycles. ~^[[:alnum:]+/]{60,}$~ OK # Put your own body patterns here.
SEE ALSO
postmap(1), Postfix lookup table manager pcre_table(5), format of PCRE tables cidr_table(5), format of CIDR tables
README FILES
Use "postconf readme_directory" or "postconf html_directory" to locate this information. DATABASE_README, Postfix lookup table overview
AUTHOR(S)
The regexp table lookup code was originally written by: LaMont Jones lamont@hp.com That code was based on the PCRE dictionary contributed by: Andrew McNamara andrewm@connect.com.au connect.com.au Pty. Ltd. Level 3, 213 Miller St North Sydney, NSW, Australia Adopted and adapted by: Wietse Venema IBM T.J. Watson Research P.O. Box 704 Yorktown Heights, NY 10598, USA REGEXP_TABLE(5)
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