Provided by: postfix_2.2.10-1_i386 bug

NAME

       scache - Postfix shared connection cache server

SYNOPSIS

       scache [generic Postfix daemon options]

DESCRIPTION

       The  scache(8)  server  maintains a shared multi-connection cache. This
       information can be used by, for example, Postfix SMTP clients or  other
       Postfix delivery agents.

       The  connection  cache  is  organized  into  logical destination names,
       physical endpoint names, and connections.

       As a specific example, logical SMTP  destinations  specify  (transport,
       domain,  port),  and  physical  SMTP  endpoints  specify (transport, IP
       address, port).  An SMTP connection may be  saved  after  a  successful
       mail transaction.

       In  the general case, one logical destination may refer to zero or more
       physical endpoints, one physical endpoint may be referenced by zero  or
       more  logical  destinations, and one endpoint may refer to zero or more
       connections.

       The  exact  syntax  of  a  logical  destination  or  endpoint  name  is
       application   dependent;   the  scache(8)  server  does  not  care.   A
       connection is stored as a file descriptor  together  with  application-
       dependent  information  that  is  needed  to  re-activate  a connection
       object. Again, the  scache(8)  server  is  completely  unaware  of  the
       details of that information.

       All  information  is  stored  with  a  finite  time to live (ttl).  The
       connection cache daemon terminates when  no  client  is  connected  for
       max_idle time units.

       This server implements the following requests:

       save_endp ttl endpoint endpoint_properties file_descriptor
              Save  the specified file descriptor and connection property data
              under the specified endpoint name. The endpoint  properties  are
              used  by  the  client  to  re-activate  a  passivated connection
              object.

       find_endp endpoint
              Look up cached properties and a cached file descriptor  for  the
              specified endpoint.

       save_dest ttl destination destination_properties endpoint
              Save  the  binding between a logical destination and an endpoint
              under the destination name, together with  destination  specific
              connection  properties.  The  destination properties are used by
              the client to re-activate a passivated connection object.

       find_dest destination
              Look  up  cached   destination   properties,   cached   endpoint
              properties,  and  a  cached  file  descriptor  for the specified
              logical destination.

SECURITY

       The scache(8) server is not security-sensitive. It does not talk to the
       network, and it does not talk to local users.  The scache(8) server can
       run chrooted at fixed low privilege.

       The scache(8) server is not a trusted process. It must not be  used  to
       store information that is security sensitive.

DIAGNOSTICS

       Problems and transactions are logged to syslogd(8).

BUGS

       The session cache cannot be shared among multiple machines.

       When  a  connection  expires  from  the cache, it is closed without the
       appropriate protocol specific handshake.

CONFIGURATION PARAMETERS

       Changes to main.cf are picked up automatically as  scache(8)  processes
       run for only a limited amount of time. Use the command "postfix reload"
       to speed up a change.

       The text below provides only a parameter summary. See  postconf(5)  for
       more details including examples.

RESOURCE CONTROLS

       connection_cache_ttl_limit (2s)
              The  maximal  time-to-live  value  that the scache(8) connection
              cache server allows.

       connection_cache_status_update_time (600s)
              How frequently the scache(8) server logs usage  statistics  with
              connection cache hit and miss rates for logical destinations and
              for physical endpoints.

MISCELLANEOUS CONTROLS

       config_directory (seepostconf -doutput)
              The default  location  of  the  Postfix  main.cf  and  master.cf
              configuration files.

       daemon_timeout (18000s)
              How  much  time  a  Postfix  daemon process may take to handle a
              request before it is terminated by a built-in watchdog timer.

       ipc_timeout (3600s)
              The time limit for sending  or  receiving  information  over  an
              internal communication channel.

       max_idle (100s)
              The  maximum  amount of time that an idle Postfix daemon process
              waits for the next service request before exiting.

       process_id (read-only)
              The process ID of a Postfix command or daemon process.

       process_name (read-only)
              The process name of a Postfix command or daemon process.

       syslog_facility (mail)
              The syslog facility of Postfix logging.

       syslog_name (postfix)
              The mail system name that is prepended to the  process  name  in
              syslog   records,   so   that   "smtpd"  becomes,  for  example,
              "postfix/smtpd".

SEE ALSO

       smtp(8), SMTP client
       postconf(5), configuration parameters
       master(8), process manager
       syslogd(8), system logging

README FILES

       Use "postconf readme_directory" or "postconf html_directory" to  locate
       this information.
       CONNECTION_CACHE_README, Postfix connection cache

LICENSE

       The Secure Mailer license must be distributed with this software.

HISTORY

       This service was introduced with Postfix version 2.2.

AUTHOR(S)

       Wietse Venema
       IBM T.J. Watson Research
       P.O. Box 704
       Yorktown Heights, NY 10598, USA

                                                                     SCACHE(8)