Provided by: postfix_2.8.5-2~build1_i386 bug

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)