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CIDR_TABLE
Section: File Formats (5)Index Return to Main Contents
NAME
cidr_table - format of Postfix CIDR tablesSYNOPSIS
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:
- pattern result
- When a search string matches the specified pattern, use the corresponding result value. The pattern must be in network/prefix or network_address form (see ADDRESS PATTERN SYNTAX below).
- !pattern result
-
When a search string does not match the specified pattern,
use the specified result value. The pattern must
be in network/prefix or network_address form (see
ADDRESS PATTERN SYNTAX below).
This feature is available in Postfix 3.2 and later.
- if pattern
- endif
-
When a search string matches the specified pattern, match
that search string against the patterns between if and
endif. The pattern must be in network/prefix or
network_address form (see ADDRESS PATTERN SYNTAX below). The
if..endif can nest.
Note: do not prepend whitespace to text between if..endif.
This feature is available in Postfix 3.2 and later.
- if !pattern
- endif
-
When a search string does not match the specified pattern,
match that search string against the patterns between if and
endif. The pattern must be in network/prefix or
network_address form (see ADDRESS PATTERN SYNTAX below). The
if..endif can nest.
Note: do not prepend whitespace to text between if..endif.
This feature is available in Postfix 3.2 and later.
- 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.
ADDRESS PATTERN SYNTAX
Postfix CIDR tables are pattern-based. A pattern is either a network_address which requires an exact match, or a network_address/prefix_length where the prefix_length part specifies the length of the network_address prefix that must be matched (the other bits in the network_address part must be zero).
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 ":" or "::", where the latter is short-hand for a sequence of one or more all-zero octet pairs. The pattern 0.0.0.0/0 matches every IPv4 address, and ::/0 matches every IPv6 address. IPv6 support is available in Postfix 2.2 and later.
Before comparisons are made, lookup keys and table entries are converted from string to binary. Therefore, IPv6 patterns will be matched regardless of leading zeros (a leading zero in an IPv4 address octet indicates octal notation).
Note: address information may be enclosed inside "[]" but this form is not required.
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
2001:db8::1 OK
2001:db8::/32 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 Wietse Venema Google, Inc. 111 8th Avenue New York, NY 10011, USA