.TH CIDR_TABLE 5 
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.SH NAME
cidr_table
\-
format of Postfix CIDR tables
.SH SYNOPSIS
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\fBpostmap -q "\fIstring\fB" cidr:/etc/postfix/\fIfilename\fR

\fBpostmap -q - cidr:/etc/postfix/\fIfilename\fR <\fIinputfile\fR
.SH DESCRIPTION
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The Postfix mail system uses optional access control tables.
These tables are usually in \fBdbm\fR or \fBdb\fR format.
Alternatively, access control tables can be specified in CIDR form.

To find out what types of lookup tables your Postfix system
supports use the \fBpostconf -m\fR command.

To test lookup tables, use the \fBpostmap\fR command as
described in the SYNOPSIS above.
.SH TABLE FORMAT
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The general form of a Postfix CIDR table is:
.IP "\fInetwork_address\fB/\fInetwork_mask     result\fR"
When a search string matches the specified network block,
use the corresponding \fIresult\fR value. Specify
0.0.0.0/0 to match every address.
.IP "\fInetwork_address     result\fR"
When a search string matches the specified network address,
use the corresponding \fIresult\fR value.
.IP "blank lines and comments"
Empty lines and whitespace-only lines are ignored, as
are lines whose first non-whitespace character is a `#'.
.IP "multi-line text"
A logical line starts with non-whitespace text. A line that
starts with whitespace continues a logical line.
.SH SEARCH ORDER
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Patterns are applied in the order as specified in the table, until a
pattern is found that matches the search string.
.SH EXAMPLE SMTPD ACCESS MAP
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/etc/postfix/main.cf:
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smtpd_client_restrictions = ... cidr:/etc/postfix/client.cidr ...

/etc/postfix/client.cidr:
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# Rule order matters. Put more specific whitelist entries
# before more general blacklist entries.
192.168.1.1             OK
192.168.0.0/16          REJECT
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.SH SEE ALSO
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regexp_table(5) format of regular expression tables
pcre_table(5) format of PCRE tables
tcp_table(5) TCP client/server table lookup protocol
.SH AUTHOR(S)
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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