TLSMGR(8) 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 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 initial-
izing 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 inter-
nal 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 exter-
nal sources.
MISCELLANEOUS CONTROLS
config_directory (see 'postconf -d' output)
The default location of the Postfix main.cf and master.cf con-
figuration 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)
A prefix that is prepended to the process name in syslog
records, so that, for example, "smtpd" becomes "prefix/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
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(8)