5 on page 277).
The Local_check_relay rule set provides a hook into the check_relay rule set, which
is used to screen incoming network connections and accept or reject them based on
the hostname, domain, or IP address. It is called just before the libwrap.a code and
can be used even if that code was omitted from your release of sendmail. Note that
the check_relay rule set is not called if sendmail was run withth e -bs command-line
switch (?§6.7.13 on page 236).
The check_relay rule set is called with a workspace that looks like this:
host $| IPaddress
* See the FEATURE(delay_checks) (?§7.5.6 on page 284) to see how that feature changes this order.
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7.1 The Local_check_ Rule Sets | 253
The hostname and IP address are separated by the $| operator. The host is the fully
qualified canonical name of the connecting host. The IPaddress is the IP address of
that host in dotted-quad form without surrounding square brackets, or the IPv6
address prefixed witha literal IPv6:. Note that if you also declare the FEATURE(use_
client_ptr) (?§7.6.6 on page 297), the value from the ${client_ptr} macro (?§21.9.23
on page 813) will be used in place of the IPaddress.
By default, the check_relay rule set allows all connections. This behavior can be
overridden or enforced in the access database by prefixing leftmost keys witha literal
Connect: (?§7.
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