#++
# NAME
#	cidr_table 5
# SUMMARY
#	format of Postfix CIDR tables
# SYNOPSIS
#	\fBpostmap -q "\fIstring\fB" cidr:/etc/postfix/\fIfilename\fR
#
#	\fBpostmap -q - cidr:/etc/postfix/\fIfilename\fB <\fIinputfile\fR
# DESCRIPTION
#	The Postfix mail system uses optional lookup tables.
#	These tables are usually in \fBdbm\fR or \fBdb\fR format.
#	Alternatively, lookup tables can be specified in CIDR
#	(Classless Inter-Domain Routing) form. In this case, each
#	input is compared against a list of patterns. 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 "\fBpostconf -m\fR" command.
#
#	To test lookup tables, use the "\fBpostmap -q\fR" command as
#	described in the SYNOPSIS above.
# TABLE FORMAT
# .ad
# .fi
#	The general form of a Postfix CIDR table is:
# .IP "\fInetwork_address\fB/\fInetwork_mask     result\fR"
#	When a search string matches the specified network block,
#	use the corresponding \fIresult\fR value. Specify
#	0.0.0.0/0 to match every IPv4 address, and ::/0 to match
#	every IPv6 address.
#
#	An IPv4 network address is a sequence of four decimal octets
#	separated by ".", and an IPv6 network address is a sequence
#	of three to eight hexadecimal octet pairs separated by ":".
#
#	The \fInetwork_mask\fR is the number of high-order bits in
#	the \fInetwork_address\fR that the search string must match.
#
#	Before comparisons are made, lookup keys and table entries
#	are converted from string to binary. Therefore table entries
#	will be matched regardless of redundant zero characters.
#
#	Note: address information may be enclosed inside "[]" but
#	this form is not required.
#
#	IPv6 support is available in Postfix 2.2 and later.
# .IP "\fInetwork_address     result\fR"
#	When a search string matches the specified network address,
#	use the corresponding \fIresult\fR value.
# .IP "blank lines and comments"
#	Empty lines and whitespace-only lines are ignored, as
#	are lines whose first non-whitespace character is a `#'.
# .IP "multi-line text"
#	A logical line starts with non-whitespace text. A line that
#	starts with whitespace continues a logical line.
# TABLE SEARCH ORDER
# .ad
# .fi
#	Patterns are applied in the order as specified in the table, until a
#	pattern is found that matches the search string.
# EXAMPLE SMTPD ACCESS MAP
# .nf
#	/etc/postfix/main.cf:
#	    smtpd_client_restrictions = ... cidr:/etc/postfix/client.cidr ...
#
#	/etc/postfix/client.cidr:
#	    # Rule order matters. Put more specific whitelist entries
#	    # before more general blacklist entries.
#	    192.168.1.1             OK
#	    192.168.0.0/16          REJECT
# .fi
# SEE ALSO
#	postmap(1), Postfix lookup table manager
#	regexp_table(5), format of regular expression tables
#	pcre_table(5), format of PCRE tables
# README FILES
# .ad
# .fi
#	Use "\fBpostconf readme_directory\fR" or
#	"\fBpostconf html_directory\fR" to locate this information.
# .na
# .nf
#	DATABASE_README, Postfix lookup table overview
# HISTORY
#	CIDR table support was introduced with Postfix version 2.1.
# AUTHOR(S)
#	The CIDR table lookup code was originally written by:
#	Jozsef Kadlecsik
#	KFKI Research Institute for Particle and Nuclear Physics
#	POB. 49
#	1525 Budapest, Hungary
#
#	Adopted and adapted by:
#	Wietse Venema
#	IBM T.J. Watson Research
#	P.O. Box 704
#	Yorktown Heights, NY 10598, USA
#
#	Wietse Venema
#	Google, Inc.
#	111 8th Avenue
#	New York, NY 10011, USA
#--