cidr_table(5)

1CIDR_TABLE(5)                 File Formats Manual                CIDR_TABLE(5)
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NAME

6       cidr_table - format of Postfix CIDR tables
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SYNOPSIS

9       postmap -q "string" cidr:/etc/postfix/filename
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11       postmap -q - cidr:/etc/postfix/filename <inputfile
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DESCRIPTION

14       The  Postfix mail system uses optional lookup tables.  These tables are
15       usually in dbm or db format.  Alternatively, lookup tables can be spec‐
16       ified in CIDR (Classless Inter-Domain Routing) form. In this case, each
17       input is compared against a list of patterns. When a  match  is  found,
18       the corresponding result is returned and the search is terminated.
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20       To  find  out  what types of lookup tables your Postfix system supports
21       use the "postconf -m" command.
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23       To test lookup tables, use the "postmap -q" command as described in the
24       SYNOPSIS above.
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TABLE FORMAT

27       The general form of a Postfix CIDR table is:
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29       pattern     result
30              When a search string matches the specified pattern, use the cor‐
31              responding result value. The pattern must be  in  network/prefix
32              or network_address form (see ADDRESS PATTERN SYNTAX below).
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34       !pattern     result
35              When  a  search string does not match the specified pattern, use
36              the specified result value. The pattern must be in  network/pre‐
37              fix or network_address form (see ADDRESS PATTERN SYNTAX below).
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39              This feature is available in Postfix 3.2 and later.
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41       if pattern
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43       endif  When  a  search string matches the specified pattern, match that
44              search string against the patterns between if  and  endif.   The
45              pattern  must  be in network/prefix or network_address form (see
46              ADDRESS PATTERN SYNTAX below). The if..endif can nest.
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48              Note: do not prepend whitespace to text between if..endif.
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50              This feature is available in Postfix 3.2 and later.
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52       if !pattern
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54       endif  When a search string does not match the specified pattern, match
55              that  search  string  against the patterns between if and endif.
56              The pattern must be in network/prefix  or  network_address  form
57              (see ADDRESS PATTERN SYNTAX below). The if..endif can nest.
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59              Note: do not prepend whitespace to text between if..endif.
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61              This feature is available in Postfix 3.2 and later.
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63       blank lines and comments
64              Empty  lines and whitespace-only lines are ignored, as are lines
65              whose first non-whitespace character is a `#'.
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67       multi-line text
68              A logical line starts with  non-whitespace  text.  A  line  that
69              starts with whitespace continues a logical line.
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TABLE SEARCH ORDER

72       Patterns  are  applied  in the order as specified in the table, until a
73       pattern is found that matches the search string.
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ADDRESS PATTERN SYNTAX

76       Postfix CIDR tables are pattern-based.  A  pattern  is  either  a  net‐
77       work_address  which  requires an exact match, or a network_address/pre‐
78       fix_length where the prefix_length part specifies  the  length  of  the
79       network_address prefix that must be matched (the other bits in the net‐
80       work_address part must be zero).
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82       An IPv4 network address is a sequence of four decimal octets  separated
83       by  ".",  and  an  IPv6 network address is a sequence of three to eight
84       hexadecimal octet pairs separated by ":" or "::", where the  latter  is
85       short-hand for a sequence of one or more all-zero octet pairs. The pat‐
86       tern 0.0.0.0/0 matches every IPv4 address, and ::/0 matches every  IPv6
87       address.  IPv6 support is available in Postfix 2.2 and later.
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89       Before  comparisons  are  made,  lookup keys and table entries are con‐
90       verted from string to binary. Therefore, IPv6 patterns will be  matched
91       regardless  of  leading  zeros (a leading zero in an IPv4 address octet
92       indicates octal notation).
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94       Note: address information may be enclosed inside "[]" but this form  is
95       not required.
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EXAMPLE SMTPD ACCESS MAP

98       /etc/postfix/main.cf:
99           smtpd_client_restrictions = ... cidr:/etc/postfix/client.cidr ...
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101       /etc/postfix/client.cidr:
102           # Rule order matters. Put more specific allowlist entries
103           # before more general denylist entries.
104           192.168.1.1             OK
105           192.168.0.0/16          REJECT
106           2001:db8::1             OK
107           2001:db8::/32           REJECT
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README FILES

115       Use  "postconf readme_directory" or "postconf html_directory" to locate
116       this information.
117       DATABASE_README, Postfix lookup table overview
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HISTORY

120       CIDR table support was introduced with Postfix version 2.1.
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AUTHOR(S)

123       The CIDR table lookup code was originally written by:
124       Jozsef Kadlecsik
125       KFKI Research Institute for Particle and Nuclear Physics
126       POB. 49
127       1525 Budapest, Hungary
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129       Adopted and adapted by:
130       Wietse Venema
131       IBM T.J. Watson Research
132       P.O. Box 704
133       Yorktown Heights, NY 10598, USA
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135       Wietse Venema
136       Google, Inc.
137       111 8th Avenue
138       New York, NY 10011, USA
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