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. 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.
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 network_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.
Patterns are applied in the order as specified in the table, until a pattern is found that matches the search string.
smtpd_client_restrictions = ... cidr:/etc/postfix/client.cidr ...
# Rule order matters. Put more specific whitelist entries
# before more general blacklist entries.
"postconf readme_directory" or
"postconf html_directory" to locate this
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
IBM T.J. Watson Research
P.O. Box 704
Yorktown Heights, NY 10598, USA
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