166 lines
8.2 KiB
HTML
166 lines
8.2 KiB
HTML
<!doctype html public "-//W3C//DTD HTML 4.01 Transitional//EN"
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"https://www.w3.org/TR/html4/loose.dtd">
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<html> <head>
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
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<link rel='stylesheet' type='text/css' href='postfix-doc.css'>
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<title> Postfix manual - scache(8) </title>
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</head> <body> <pre>
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SCACHE(8) SCACHE(8)
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<b><a name="name">NAME</a></b>
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scache - Postfix shared connection cache server
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<b><a name="synopsis">SYNOPSIS</a></b>
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<b>scache</b> [generic Postfix daemon options]
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<b><a name="description">DESCRIPTION</a></b>
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The <a href="scache.8.html"><b>scache</b>(8)</a> server maintains a shared multi-connection cache. This
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information can be used by, for example, Postfix SMTP clients or other
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Postfix delivery agents.
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The connection cache is organized into logical destination names, phys-
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ical endpoint names, and connections.
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As a specific example, logical SMTP destinations specify (transport,
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domain, port), and physical SMTP endpoints specify (transport, IP
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address, port). An SMTP connection may be saved after a successful
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mail transaction.
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In the general case, one logical destination may refer to zero or more
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physical endpoints, one physical endpoint may be referenced by zero or
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more logical destinations, and one endpoint may refer to zero or more
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connections.
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The exact syntax of a logical destination or endpoint name is applica-
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tion dependent; the <a href="scache.8.html"><b>scache</b>(8)</a> server does not care. A connection is
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stored as a file descriptor together with application-dependent infor-
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mation that is needed to re-activate a connection object. Again, the
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<a href="scache.8.html"><b>scache</b>(8)</a> server is completely unaware of the details of that informa-
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tion.
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All information is stored with a finite time to live (ttl). The con-
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nection cache daemon terminates when no client is connected for
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<b><a href="postconf.5.html#max_idle">max_idle</a></b> time units.
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This server implements the following requests:
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<b>save_endp</b> <i>ttl endpoint endpoint</i><b>_</b><i>properties file</i><b>_</b><i>descriptor</i>
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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 are
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used by the client to re-activate a passivated connection
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object.
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<b>find_endp</b> <i>endpoint</i>
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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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<b>save_dest</b> <i>ttl destination destination</i><b>_</b><i>properties endpoint</i>
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Save the binding between a logical destination and an endpoint
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under the destination name, together with destination specific
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connection properties. The destination properties are used by
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the client to re-activate a passivated connection object.
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<b>find_dest</b> <i>destination</i>
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Look up cached destination properties, cached endpoint proper-
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ties, and a cached file descriptor for the specified logical
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destination.
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<b><a name="security">SECURITY</a></b>
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The <a href="scache.8.html"><b>scache</b>(8)</a> server is not security-sensitive. It does not talk to the
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network, and it does not talk to local users. The <a href="scache.8.html"><b>scache</b>(8)</a> server can
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run chrooted at fixed low privilege.
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The <a href="scache.8.html"><b>scache</b>(8)</a> server is not a trusted process. It must not be used to
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store information that is security sensitive.
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<b><a name="diagnostics">DIAGNOSTICS</a></b>
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Problems and transactions are logged to <b>syslogd</b>(8) or <a href="postlogd.8.html"><b>postlogd</b>(8)</a>.
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<b><a name="bugs">BUGS</a></b>
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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 the
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appropriate protocol specific handshake.
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<b><a name="configuration_parameters">CONFIGURATION PARAMETERS</a></b>
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Changes to <a href="postconf.5.html"><b>main.cf</b></a> are picked up automatically as <a href="scache.8.html"><b>scache</b>(8)</a> processes
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run for only a limited amount of time. Use the command "<b>postfix reload</b>"
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to speed up a change.
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The text below provides only a parameter summary. See <a href="postconf.5.html"><b>postconf</b>(5)</a> for
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more details including examples.
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<b><a name="resource_controls">RESOURCE CONTROLS</a></b>
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<b><a href="postconf.5.html#connection_cache_ttl_limit">connection_cache_ttl_limit</a> (2s)</b>
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The maximal time-to-live value that the <a href="scache.8.html"><b>scache</b>(8)</a> connection
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cache server allows.
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<b><a href="postconf.5.html#connection_cache_status_update_time">connection_cache_status_update_time</a> (600s)</b>
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How frequently the <a href="scache.8.html"><b>scache</b>(8)</a> server logs usage statistics with
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connection cache hit and miss rates for logical destinations and
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for physical endpoints.
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<b><a name="miscellaneous_controls">MISCELLANEOUS CONTROLS</a></b>
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<b><a href="postconf.5.html#config_directory">config_directory</a> (see 'postconf -d' output)</b>
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The default location of the Postfix <a href="postconf.5.html">main.cf</a> and <a href="master.5.html">master.cf</a> con-
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figuration files.
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<b><a href="postconf.5.html#daemon_timeout">daemon_timeout</a> (18000s)</b>
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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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<b><a href="postconf.5.html#ipc_timeout">ipc_timeout</a> (3600s)</b>
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The time limit for sending or receiving information over an
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internal communication channel.
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<b><a href="postconf.5.html#max_idle">max_idle</a> (100s)</b>
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The maximum amount of time that an idle Postfix daemon process
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waits for an incoming connection before terminating voluntarily.
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<b><a href="postconf.5.html#process_id">process_id</a> (read-only)</b>
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The process ID of a Postfix command or daemon process.
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<b><a href="postconf.5.html#process_name">process_name</a> (read-only)</b>
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The process name of a Postfix command or daemon process.
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<b><a href="postconf.5.html#syslog_facility">syslog_facility</a> (mail)</b>
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The syslog facility of Postfix logging.
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<b><a href="postconf.5.html#syslog_name">syslog_name</a> (see 'postconf -d' output)</b>
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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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Available in Postfix 3.3 and later:
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<b><a href="postconf.5.html#service_name">service_name</a> (read-only)</b>
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The <a href="master.5.html">master.cf</a> service name of a Postfix daemon process.
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<b><a name="see_also">SEE ALSO</a></b>
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<a href="smtp.8.html">smtp(8)</a>, SMTP client
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<a href="postconf.5.html">postconf(5)</a>, configuration parameters
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<a href="master.8.html">master(8)</a>, process manager
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<a href="postlogd.8.html">postlogd(8)</a>, Postfix logging
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syslogd(8), system logging
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<b><a name="readme_files">README FILES</a></b>
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<a href="CONNECTION_CACHE_README.html">CONNECTION_CACHE_README</a>, Postfix connection cache
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<b><a name="license">LICENSE</a></b>
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The Secure Mailer license must be distributed with this software.
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<b><a name="history">HISTORY</a></b>
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This service was introduced with Postfix version 2.2.
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<b>AUTHOR(S)</b>
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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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SCACHE(8)
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</pre> </body> </html>
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