Back to main site | Back to man page index

TLSMGR(8)                                      System Manager's Manual                                      TLSMGR(8)



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  peri‐
       odically  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 warn‐
       ing 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 com‐
       mand "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.

       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
       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



                                                                                                            TLSMGR(8)