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