centos man page for cidr_table

CIDR_TABLE(5)							File Formats Manual						     CIDR_TABLE(5)

NAME
       cidr_table - format of Postfix CIDR tables

SYNOPSIS
       postmap -q "string" cidr:/etc/postfix/filename

       postmap -q - cidr:/etc/postfix/filename <inputfile

DESCRIPTION
       The  Postfix  mail  system uses optional lookup tables.	These tables are usually in dbm or db 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 "postconf -m" command.

       To test lookup tables, use the "postmap -q" command as described in the SYNOPSIS above.

TABLE FORMAT
       The general form of a Postfix CIDR table is:

       network_address/network_mask	result
	      When  a search string matches the specified network block, use the corresponding result 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 ":".

	      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.

       network_address	   result
	      When a search string matches the specified network address, use the corresponding result value.

       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.

TABLE SEARCH ORDER
       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
       /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

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
       Use "postconf readme_directory" or "postconf html_directory" to locate this information.
       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

																     CIDR_TABLE(5)