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CIDR_TABLE(5) File Formats Manual 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 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:
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 ":".
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.
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.
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
/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
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
CIDR_TABLE(5)
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