cidr_table - format of Postfix CIDR tables

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

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

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.

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.

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 recommended.

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.

Patterns are applied in the order as specified in the table, until a pattern is found that matches the search string.

/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

postmap(1), Postfix lookup table manager
regexp_table(5), format of regular expression tables
pcre_table(5), format of PCRE tables

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

DATABASE_README, Postfix lookup table overview

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