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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 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
The general form of a Postfix CIDR table is:
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.
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 `#'.
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
smtpd_client_restrictions = ... cidr:/etc/postfix/client.cidr ...
# Rule order matters. Put more specific whitelist entries
# before more general blacklist entries.
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
DATABASE_README, Postfix lookup table overview
CIDR table support was introduced with Postfix version 2.1.
The CIDR table lookup code was originally written by:
KFKI Research Institute for Particle and Nuclear Physics
1525 Budapest, Hungary
Adopted and adapted by:
IBM T.J. Watson Research
P.O. Box 704
Yorktown Heights, NY 10598, USA