1<!doctype html public "-//W3C//DTD HTML 4.01 Transitional//EN" 2 "http://www.w3.org/TR/html4/loose.dtd"> 3<html> <head> 4<meta http-equiv="Content-Type" content="text/html; charset=utf-8"> 5<link rel='stylesheet' type='text/css' href='postfix-doc.css'> 6<title> Postfix manual - scache(8) </title> 7</head> <body> <pre> 8SCACHE(8) SCACHE(8) 9 10<b>NAME</b> 11 scache - Postfix shared connection cache server 12 13<b>SYNOPSIS</b> 14 <b>scache</b> [generic Postfix daemon options] 15 16<b>DESCRIPTION</b> 17 The <a href="scache.8.html"><b>scache</b>(8)</a> server maintains a shared multi-connection cache. This 18 information can be used by, for example, Postfix SMTP clients or other 19 Postfix delivery agents. 20 21 The connection cache is organized into logical destination names, phys- 22 ical endpoint names, and connections. 23 24 As a specific example, logical SMTP destinations specify (transport, 25 domain, port), and physical SMTP endpoints specify (transport, IP 26 address, port). An SMTP connection may be saved after a successful 27 mail transaction. 28 29 In the general case, one logical destination may refer to zero or more 30 physical endpoints, one physical endpoint may be referenced by zero or 31 more logical destinations, and one endpoint may refer to zero or more 32 connections. 33 34 The exact syntax of a logical destination or endpoint name is applica- 35 tion dependent; the <a href="scache.8.html"><b>scache</b>(8)</a> server does not care. A connection is 36 stored as a file descriptor together with application-dependent infor- 37 mation that is needed to re-activate a connection object. Again, the 38 <a href="scache.8.html"><b>scache</b>(8)</a> server is completely unaware of the details of that informa- 39 tion. 40 41 All information is stored with a finite time to live (ttl). The con- 42 nection cache daemon terminates when no client is connected for 43 <b><a href="postconf.5.html#max_idle">max_idle</a></b> time units. 44 45 This server implements the following requests: 46 47 <b>save_endp</b> <i>ttl endpoint endpoint</i><b>_</b><i>properties file</i><b>_</b><i>descriptor</i> 48 Save the specified file descriptor and connection property data 49 under the specified endpoint name. The endpoint properties are 50 used by the client to re-activate a passivated connection 51 object. 52 53 <b>find_endp</b> <i>endpoint</i> 54 Look up cached properties and a cached file descriptor for the 55 specified endpoint. 56 57 <b>save_dest</b> <i>ttl destination destination</i><b>_</b><i>properties endpoint</i> 58 Save the binding between a logical destination and an endpoint 59 under the destination name, together with destination specific 60 connection properties. The destination properties are used by 61 the client to re-activate a passivated connection object. 62 63 <b>find_dest</b> <i>destination</i> 64 Look up cached destination properties, cached endpoint proper- 65 ties, and a cached file descriptor for the specified logical 66 destination. 67 68<b>SECURITY</b> 69 The <a href="scache.8.html"><b>scache</b>(8)</a> server is not security-sensitive. It does not talk to the 70 network, and it does not talk to local users. The <a href="scache.8.html"><b>scache</b>(8)</a> server can 71 run chrooted at fixed low privilege. 72 73 The <a href="scache.8.html"><b>scache</b>(8)</a> server is not a trusted process. It must not be used to 74 store information that is security sensitive. 75 76<b>DIAGNOSTICS</b> 77 Problems and transactions are logged to <b>syslogd</b>(8) or <a href="postlogd.8.html"><b>postlogd</b>(8)</a>. 78 79<b>BUGS</b> 80 The session cache cannot be shared among multiple machines. 81 82 When a connection expires from the cache, it is closed without the 83 appropriate protocol specific handshake. 84 85<b>CONFIGURATION PARAMETERS</b> 86 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 87 run for only a limited amount of time. Use the command "<b>postfix reload</b>" 88 to speed up a change. 89 90 The text below provides only a parameter summary. See <a href="postconf.5.html"><b>postconf</b>(5)</a> for 91 more details including examples. 92 93<b>RESOURCE CONTROLS</b> 94 <b><a href="postconf.5.html#connection_cache_ttl_limit">connection_cache_ttl_limit</a> (2s)</b> 95 The maximal time-to-live value that the <a href="scache.8.html"><b>scache</b>(8)</a> connection 96 cache server allows. 97 98 <b><a href="postconf.5.html#connection_cache_status_update_time">connection_cache_status_update_time</a> (600s)</b> 99 How frequently the <a href="scache.8.html"><b>scache</b>(8)</a> server logs usage statistics with 100 connection cache hit and miss rates for logical destinations and 101 for physical endpoints. 102 103<b>MISCELLANEOUS CONTROLS</b> 104 <b><a href="postconf.5.html#config_directory">config_directory</a> (see 'postconf -d' output)</b> 105 The default location of the Postfix <a href="postconf.5.html">main.cf</a> and <a href="master.5.html">master.cf</a> con- 106 figuration files. 107 108 <b><a href="postconf.5.html#daemon_timeout">daemon_timeout</a> (18000s)</b> 109 How much time a Postfix daemon process may take to handle a 110 request before it is terminated by a built-in watchdog timer. 111 112 <b><a href="postconf.5.html#ipc_timeout">ipc_timeout</a> (3600s)</b> 113 The time limit for sending or receiving information over an 114 internal communication channel. 115 116 <b><a href="postconf.5.html#max_idle">max_idle</a> (100s)</b> 117 The maximum amount of time that an idle Postfix daemon process 118 waits for an incoming connection before terminating voluntarily. 119 120 <b><a href="postconf.5.html#process_id">process_id</a> (read-only)</b> 121 The process ID of a Postfix command or daemon process. 122 123 <b><a href="postconf.5.html#process_name">process_name</a> (read-only)</b> 124 The process name of a Postfix command or daemon process. 125 126 <b><a href="postconf.5.html#syslog_facility">syslog_facility</a> (mail)</b> 127 The syslog facility of Postfix logging. 128 129 <b><a href="postconf.5.html#syslog_name">syslog_name</a> (see 'postconf -d' output)</b> 130 A prefix that is prepended to the process name in syslog 131 records, so that, for example, "smtpd" becomes "prefix/smtpd". 132 133 Available in Postfix 3.3 and later: 134 135 <b><a href="postconf.5.html#service_name">service_name</a> (read-only)</b> 136 The <a href="master.5.html">master.cf</a> service name of a Postfix daemon process. 137 138<b>SEE ALSO</b> 139 <a href="smtp.8.html">smtp(8)</a>, SMTP client 140 <a href="postconf.5.html">postconf(5)</a>, configuration parameters 141 <a href="master.8.html">master(8)</a>, process manager 142 <a href="postlogd.8.html">postlogd(8)</a>, Postfix logging 143 syslogd(8), system logging 144 145<b>README FILES</b> 146 <a href="CONNECTION_CACHE_README.html">CONNECTION_CACHE_README</a>, Postfix connection cache 147 148<b>LICENSE</b> 149 The Secure Mailer license must be distributed with this software. 150 151<b>HISTORY</b> 152 This service was introduced with Postfix version 2.2. 153 154<b>AUTHOR(S)</b> 155 Wietse Venema 156 IBM T.J. Watson Research 157 P.O. Box 704 158 Yorktown Heights, NY 10598, USA 159 160 Wietse Venema 161 Google, Inc. 162 111 8th Avenue 163 New York, NY 10011, USA 164 165 SCACHE(8) 166</pre> </body> </html> 167