CIDR_TABLE(5)                                                    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 spec-
       ified 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 ":".

              The  network_mask  is  the number of high-order bits in the net-
              work_address 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.

       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)

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