178 lines
5.5 KiB
Groff
178 lines
5.5 KiB
Groff
.TH SCACHE 8
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.ad
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.fi
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.SH NAME
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scache
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\-
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Postfix shared connection cache server
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.SH "SYNOPSIS"
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.nf
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\fBscache\fR [generic Postfix daemon options]
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.SH DESCRIPTION
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.ad
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.fi
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The \fBscache\fR(8) server maintains a shared multi\-connection
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cache. This information can be used by, for example, Postfix
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SMTP clients or other Postfix delivery agents.
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The connection cache is organized into logical destination
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names, physical endpoint names, and connections.
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As a specific example, logical SMTP destinations specify
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(transport, domain, port), and physical SMTP endpoints
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specify (transport, IP address, port). An SMTP connection
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may be saved after a successful mail transaction.
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In the general case, one logical destination may refer to
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zero or more physical endpoints, one physical endpoint may
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be referenced by zero or more logical destinations, and
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one endpoint may refer to zero or more connections.
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The exact syntax of a logical destination or endpoint name
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is application dependent; the \fBscache\fR(8) server does
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not care. A connection is stored as a file descriptor together
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with application\-dependent information that is needed to
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re\-activate a connection object. Again, the \fBscache\fR(8)
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server is completely unaware of the details of that
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information.
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All information is stored with a finite time to live (ttl).
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The connection cache daemon terminates when no client is
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connected for \fBmax_idle\fR time units.
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This server implements the following requests:
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.IP "\fBsave_endp\fI ttl endpoint endpoint_properties file_descriptor\fR"
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Save the specified file descriptor and connection property data
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under the specified endpoint name. The endpoint properties
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are used by the client to re\-activate a passivated connection
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object.
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.IP "\fBfind_endp\fI endpoint\fR"
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Look up cached properties and a cached file descriptor for the
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specified endpoint.
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.IP "\fBsave_dest\fI ttl destination destination_properties endpoint\fR"
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Save the binding between a logical destination and an
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endpoint under the destination name, together with destination
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specific connection properties. The destination properties
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are used by the client to re\-activate a passivated connection
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object.
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.IP "\fBfind_dest\fI destination\fR"
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Look up cached destination properties, cached endpoint properties,
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and a cached file descriptor for the specified logical destination.
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.SH "SECURITY"
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.nf
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.ad
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.fi
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The \fBscache\fR(8) server is not security\-sensitive. It does not
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talk to the network, and it does not talk to local users.
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The \fBscache\fR(8) server can run chrooted at fixed low privilege.
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The \fBscache\fR(8) server is not a trusted process. It must
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not be used to store information that is security sensitive.
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.SH DIAGNOSTICS
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.ad
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.fi
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Problems and transactions are logged to \fBsyslogd\fR(8)
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or \fBpostlogd\fR(8).
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.SH BUGS
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.ad
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.fi
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The session cache cannot be shared among multiple machines.
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When a connection expires from the cache, it is closed without
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the appropriate protocol specific handshake.
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.SH "CONFIGURATION PARAMETERS"
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.nf
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.ad
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.fi
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Changes to \fBmain.cf\fR are picked up automatically as \fBscache\fR(8)
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processes run for only a limited amount of time. Use the command
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"\fBpostfix reload\fR" to speed up a change.
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The text below provides only a parameter summary. See
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\fBpostconf\fR(5) for more details including examples.
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.SH "RESOURCE CONTROLS"
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.nf
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.IP "\fBconnection_cache_ttl_limit (2s)\fR"
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The maximal time\-to\-live value that the \fBscache\fR(8) connection
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cache server
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allows.
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.IP "\fBconnection_cache_status_update_time (600s)\fR"
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How frequently the \fBscache\fR(8) server logs usage statistics with
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connection cache hit and miss rates for logical destinations and for
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physical endpoints.
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.SH "MISCELLANEOUS CONTROLS"
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.nf
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.IP "\fBconfig_directory (see 'postconf -d' output)\fR"
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The default location of the Postfix main.cf and master.cf
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configuration files.
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.IP "\fBdaemon_timeout (18000s)\fR"
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How much time a Postfix daemon process may take to handle a
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request before it is terminated by a built\-in watchdog timer.
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.IP "\fBipc_timeout (3600s)\fR"
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The time limit for sending or receiving information over an internal
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communication channel.
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.IP "\fBmax_idle (100s)\fR"
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The maximum amount of time that an idle Postfix daemon process waits
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for an incoming connection before terminating voluntarily.
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.IP "\fBprocess_id (read\-only)\fR"
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The process ID of a Postfix command or daemon process.
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.IP "\fBprocess_name (read\-only)\fR"
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The process name of a Postfix command or daemon process.
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.IP "\fBsyslog_facility (mail)\fR"
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The syslog facility of Postfix logging.
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.IP "\fBsyslog_name (see 'postconf -d' output)\fR"
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A prefix that is prepended to the process name in syslog
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records, so that, for example, "smtpd" becomes "prefix/smtpd".
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.PP
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Available in Postfix 3.3 and later:
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.IP "\fBservice_name (read\-only)\fR"
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The master.cf service name of a Postfix daemon process.
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.SH "SEE ALSO"
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.nf
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smtp(8), SMTP client
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postconf(5), configuration parameters
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master(8), process manager
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postlogd(8), Postfix logging
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syslogd(8), system logging
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.SH "README FILES"
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.nf
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.ad
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.fi
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Use "\fBpostconf readme_directory\fR" or
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"\fBpostconf html_directory\fR" to locate this information.
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CONNECTION_CACHE_README, Postfix connection cache
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.SH "LICENSE"
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.na
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.nf
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.ad
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.fi
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The Secure Mailer license must be distributed with this software.
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.SH HISTORY
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.ad
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.fi
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This service was introduced with Postfix version 2.2.
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.SH "AUTHOR(S)"
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.nf
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Wietse Venema
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IBM T.J. Watson Research
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P.O. Box 704
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Yorktown Heights, NY 10598, USA
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Wietse Venema
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Google, Inc.
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111 8th Avenue
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New York, NY 10011, USA
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