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 access control tables. These tables are usually in dbm or db format. Alternatively, access control tables can be specified in CIDR form. To find out what types of lookup tables your Postfix system supports use the postconf -m command. To test lookup tables, use the postmap 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 address.

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.

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
regexp_table(5) format of regular expression tables
pcre_table(5) format of PCRE tables
tcp_table(5) TCP client/server table lookup protocol

AUTHOR(S)
The CIDR table lookup code was originally written by:
Jozsef Kadlecsik
kadlec@blackhole.kfki.hu
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