NAME

       tlsmgr - Postfix TLS session cache and PRNG manager

SYNOPSIS

       tlsmgr [generic Postfix daemon options]

DESCRIPTION

       The  tlsmgr(8)  manages  the  Postfix  TLS  session caches.  It stores and retrieves cache
       entries on request by smtpd(8) and smtp(8) processes,  and  periodically  removes  entries
       that have expired.

       The  tlsmgr(8)  also  manages  the  PRNG (pseudo random number generator) pool. It answers
       queries by the smtpd(8) and smtp(8) processes to seed their internal PRNG pools.

       The tlsmgr(8)'s PRNG pool is initially seeded from an external source (EGD,  /dev/urandom,
       or  regular  file).   It is updated at configurable pseudo-random intervals with data from
       the external source. It is updated periodically with data from TLS session  cache  entries
       and  with the time of day, and is updated with the time of day whenever a process requests
       tlsmgr(8) service.

       The tlsmgr(8) saves the PRNG state to an exchange file periodically and when  the  process
       terminates, and reads the exchange file when initializing its PRNG.

SECURITY

       The tlsmgr(8) is not security-sensitive. The code that maintains the external and internal
       PRNG pools does not "trust" the data that it manipulates, and the code that maintains  the
       TLS  session  cache  does not touch the contents of the cached entries, except for seeding
       its internal PRNG pool.

       The tlsmgr(8) can be run chrooted and with reduced  privileges.   At  process  startup  it
       connects  to  the  entropy source and exchange file, and creates or truncates the optional
       TLS session cache files.

       With Postfix version 2.5 and later, the tlsmgr(8) no  longer  uses  root  privileges  when
       opening   cache   files.  These  files  should  now  be  stored  under  the  Postfix-owned
       data_directory.  As a migration aid, an attempt to open a cache file under  a  non-Postfix
       directory is redirected to the Postfix-owned data_directory, and a warning is logged.

DIAGNOSTICS

       Problems and transactions are logged to the syslog daemon.

BUGS

       There  is  no  automatic  means  to  limit the number of entries in the TLS session caches
       and/or the size of the TLS cache files.

CONFIGURATION PARAMETERS

       Changes to main.cf are not picked up automatically,  because  tlsmgr(8)  is  a  persistent
       processes.  Use the command "postfix reload" after a configuration change.

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

TLS SESSION CACHE

       lmtp_tls_loglevel (0)
              The LMTP-specific version of the smtp_tls_loglevel configuration parameter.

       lmtp_tls_session_cache_database (empty)
              The LMTP-specific  version  of  the  smtp_tls_session_cache_database  configuration
              parameter.

       lmtp_tls_session_cache_timeout (3600s)
              The  LMTP-specific  version  of  the  smtp_tls_session_cache_timeout  configuration
              parameter.

       smtp_tls_loglevel (0)
              Enable additional Postfix SMTP client logging of TLS activity.

       smtp_tls_session_cache_database (empty)
              Name of the file containing the optional Postfix SMTP client TLS session cache.

       smtp_tls_session_cache_timeout (3600s)
              The expiration time of Postfix SMTP client TLS session cache information.

       smtpd_tls_loglevel (0)
              Enable additional Postfix SMTP server logging of TLS activity.

       smtpd_tls_session_cache_database (empty)
              Name of the file containing the optional Postfix SMTP server TLS session cache.

       smtpd_tls_session_cache_timeout (3600s)
              The expiration time of Postfix SMTP server TLS session cache information.

PSEUDO RANDOM NUMBER GENERATOR

       tls_random_source (see 'postconf -d' output)
              The external entropy source  for  the  in-memory  tlsmgr(8)  pseudo  random  number
              generator (PRNG) pool.

       tls_random_bytes (32)
              The  number  of bytes that tlsmgr(8) reads from $tls_random_source when (re)seeding
              the in-memory pseudo random number generator (PRNG) pool.

       tls_random_exchange_name (see 'postconf -d' output)
              Name of the pseudo random number generator (PRNG) state file that is maintained  by
              tlsmgr(8).

       tls_random_prng_update_period (3600s)
              The  time  between  attempts  by  tlsmgr(8)  to save the state of the pseudo random
              number generator (PRNG) to the file specified with $tls_random_exchange_name.

       tls_random_reseed_period (3600s)
              The maximal time between attempts by tlsmgr(8)  to  re-seed  the  in-memory  pseudo
              random number generator (PRNG) pool from external sources.

MISCELLANEOUS CONTROLS

       config_directory (see 'postconf -d' output)
              The default location of the Postfix main.cf and master.cf configuration files.

       data_directory (see 'postconf -d' output)
              The  directory with Postfix-writable data files (for example: caches, pseudo-random
              numbers).

       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.

       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 (see 'postconf -d' output)
              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), Postfix SMTP client
       smtpd(8), Postfix SMTP server
       postconf(5), configuration parameters
       master(5), generic daemon options
       master(8), process manager
       syslogd(8), system logging

README FILES

       Use "postconf readme_directory" or "postconf html_directory" to locate this information.
       TLS_README, Postfix TLS configuration and operation

LICENSE

       The Secure Mailer license must be distributed with this software.

HISTORY

       This service was introduced with Postfix version 2.2.

AUTHOR(S)

       Lutz Jaenicke
       BTU Cottbus
       Allgemeine Elektrotechnik
       Universitaetsplatz 3-4
       D-03044 Cottbus, Germany

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

       Wietse Venema
       Google, Inc.
       111 8th Avenue
       New York, NY 10011, USA

                                                                                 TLSMGR(8postfix)