NAME

tlsmgr - Postfix TLS session cache and PRNG manager

SYNOPSIS


ttllssmmggrr [generic Postfix daemon options]

DESCRIPTION

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

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

The ttllssmmggrr(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 ttllssmmggrr(8) service.

The ttllssmmggrr(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 ttllssmmggrr(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 ttllssmmggrr(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 ttllssmmggrr(8) no longer uses root privileges when opening cache files. These files should now be stored under the Postfix-owned ddaattaa__ddiirreeccttoorryy. As a migration aid, an attempt to open a cache file under a non-Postfix directory is redirected to the Postfix-owned ddaattaa__ddiirreeccttoorryy, 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 mmaaiinn..ccff are not picked up automatically,
because ttllssmmggrr(8) is a persistent processes.  Use the
command "ppoossttffiixx rreellooaadd" after a configuration change.
        

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

TLS SESSION CACHE



llmmttpp__ttllss__lloogglleevveell ((00)) The LMTP-specific version of the smtp_tls_loglevel
configuration parameter.
llmmttpp__ttllss__sseessssiioonn__ccaacchhee__ddaattaabbaassee ((eemmppttyy)) The LMTP-specific version of the smtp_tls_session_cache_database
configuration parameter.
llmmttpp__ttllss__sseessssiioonn__ccaacchhee__ttiimmeeoouutt ((33660000ss)) The LMTP-specific version of the smtp_tls_session_cache_timeout
configuration parameter.
ssmmttpp__ttllss__lloogglleevveell ((00)) Enable additional Postfix SMTP client logging of TLS activity.
ssmmttpp__ttllss__sseessssiioonn__ccaacchhee__ddaattaabbaassee ((eemmppttyy)) Name of the file containing the optional Postfix SMTP client
TLS session cache.
ssmmttpp__ttllss__sseessssiioonn__ccaacchhee__ttiimmeeoouutt ((33660000ss)) The expiration time of Postfix SMTP client TLS session cache
information.
ssmmttppdd__ttllss__lloogglleevveell ((00)) Enable additional Postfix SMTP server logging of TLS activity.
ssmmttppdd__ttllss__sseessssiioonn__ccaacchhee__ddaattaabbaassee ((eemmppttyy)) Name of the file containing the optional Postfix SMTP server
TLS session cache.
ssmmttppdd__ttllss__sseessssiioonn__ccaacchhee__ttiimmeeoouutt ((33660000ss)) The expiration time of Postfix SMTP server TLS session cache
information.

PSEUDO RANDOM NUMBER GENERATOR



ttllss__rraannddoomm__ssoouurrccee ((sseeee ''ppoossttccoonnff --dd'' oouuttppuutt)) The external entropy source for the in-memory ttllssmmggrr(8) pseudo
random number generator (PRNG) pool.
ttllss__rraannddoomm__bbyytteess ((3322)) The number of bytes that ttllssmmggrr(8) reads from $tls_random_source
when (re)seeding the in-memory pseudo random number generator (PRNG) pool.
ttllss__rraannddoomm__eexxcchhaannggee__nnaammee ((sseeee ''ppoossttccoonnff --dd'' oouuttppuutt)) Name of the pseudo random number generator (PRNG) state file
that is maintained by ttllssmmggrr(8).
ttllss__rraannddoomm__pprrnngg__uuppddaattee__ppeerriioodd ((33660000ss)) The time between attempts by ttllssmmggrr(8) to save the state of
the pseudo random number generator (PRNG) to the file specified with $tls_random_exchange_name.
ttllss__rraannddoomm__rreesseeeedd__ppeerriioodd ((33660000ss)) The maximal time between attempts by ttllssmmggrr(8) to re-seed the
in-memory pseudo random number generator (PRNG) pool from external sources.

MISCELLANEOUS CONTROLS



ccoonnffiigg__ddiirreeccttoorryy ((sseeee ''ppoossttccoonnff --dd'' oouuttppuutt)) The default location of the Postfix main.cf and master.cf
configuration files.
ddaattaa__ddiirreeccttoorryy ((sseeee ''ppoossttccoonnff --dd'' oouuttppuutt)) The directory with Postfix-writable data files (for example:
caches, pseudo-random numbers).
ddaaeemmoonn__ttiimmeeoouutt ((1188000000ss)) How much time a Postfix daemon process may take to handle a
request before it is terminated by a built-in watchdog timer.
pprroocceessss__iidd ((rreeaadd--oonnllyy)) The process ID of a Postfix command or daemon process.
pprroocceessss__nnaammee ((rreeaadd--oonnllyy)) The process name of a Postfix command or daemon process.
ssyysslloogg__ffaacciilliittyy ((mmaaiill)) The syslog facility of Postfix logging.
ssyysslloogg__nnaammee ((sseeee ''ppoossttccoonnff --dd'' oouuttppuutt)) 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 "ppoossttccoonnff rreeaaddmmee__ddiirreeccttoorryy" or
"ppoossttccoonnff hhttmmll__ddiirreeccttoorryy" to locate this information.

TLS_README, Postfix TLS configuration and operation

LICENSE



The Secure Mailer license must be distributed with this software.

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