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




NAME
       tlsproxy - Postfix TLS proxy

SYNOPSIS
       tlsproxy [generic Postfix daemon options]

DESCRIPTION
       The tlsproxy(8) server implements a server-side TLS proxy. It is used
       by postscreen(8) to talk SMTP-over-TLS with remote SMTP clients whose
       whitelist status has expired, but it should also work for non-SMTP
       protocols.

       Although one tlsproxy(8) process can serve multiple sessions at the
       same time, it is a good idea to allow the number of processes to
       increase with load, so that the service remains responsive.

PROTOCOL EXAMPLE
       The example below concerns postscreen(8). However, the tlsproxy(8)
       server is agnostic of the application protocol, and the example is
       easily adapted to other applications.

       The postscreen(8) server sends the remote SMTP client endpoint string,
       the requested role (server), and the requested timeout to tlsproxy(8).
       postscreen(8) then receives a "TLS available" indication from
       tlsproxy(8).  If the TLS service is available, postscreen(8) sends the
       remote SMTP client file descriptor to tlsproxy(8), and sends the
       plaintext 220 greeting to the remote SMTP client.  This triggers TLS
       negotiations between the remote SMTP client and tlsproxy(8).  Upon
       completion of the TLS-level handshake, tlsproxy(8) translates between
       plaintext from/to postscreen(8) and ciphertext to/from the remote SMTP
       client.

SECURITY
       The tlsproxy(8) server is moderately security-sensitive.  It talks to
       untrusted clients on the network. The process can be run chrooted at
       fixed low privilege.

DIAGNOSTICS
       Problems and transactions are logged to syslogd(8).

CONFIGURATION PARAMETERS
       Changes to main.cf are not picked up automatically, as tlsproxy(8)
       processes may run for a long time depending on mail server load.  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.

STARTTLS SUPPORT CONTROLS

       tlsproxy_tls_CAfile ($smtpd_tls_CAfile)
              A file containing (PEM format) CA certificates of root CAs
              trusted to sign either remote SMTP client certificates or
              intermediate CA certificates.

       tlsproxy_tls_CApath ($smtpd_tls_CApath)
              A directory containing (PEM format) CA certificates of root CAs
              trusted to sign either remote SMTP client certificates or
              intermediate CA certificates.

       tlsproxy_tls_always_issue_session_ids
              ($smtpd_tls_always_issue_session_ids)
              Force the Postfix tlsproxy(8) server to issue a TLS session id,
              even when TLS session caching is turned off.

       tlsproxy_tls_ask_ccert ($smtpd_tls_ask_ccert)
              Ask a remote SMTP client for a client certificate.

       tlsproxy_tls_ccert_verifydepth ($smtpd_tls_ccert_verifydepth)
              The verification depth for remote SMTP client certificates.

       tlsproxy_tls_cert_file ($smtpd_tls_cert_file)
              File with the Postfix tlsproxy(8) server RSA certificate in PEM
              format.

       tlsproxy_tls_ciphers ($smtpd_tls_ciphers)
              The minimum TLS cipher grade that the Postfix tlsproxy(8) server
              will use with opportunistic TLS encryption.

       tlsproxy_tls_dcert_file ($smtpd_tls_dcert_file)
              File with the Postfix tlsproxy(8) server DSA certificate in PEM
              format.

       tlsproxy_tls_dh1024_param_file ($smtpd_tls_dh1024_param_file)
              File with DH parameters that the Postfix tlsproxy(8) server
              should use with EDH ciphers.

       tlsproxy_tls_dh512_param_file ($smtpd_tls_dh512_param_file)
              File with DH parameters that the Postfix tlsproxy(8) server
              should use with EDH ciphers.

       tlsproxy_tls_dkey_file ($smtpd_tls_dkey_file)
              File with the Postfix tlsproxy(8) server DSA private key in PEM
              format.

       tlsproxy_tls_eccert_file ($smtpd_tls_eccert_file)
              File with the Postfix tlsproxy(8) server ECDSA certificate in
              PEM format.

       tlsproxy_tls_eckey_file ($smtpd_tls_eckey_file)
              File with the Postfix tlsproxy(8) server ECDSA private key in
              PEM format.

       tlsproxy_tls_eecdh_grade ($smtpd_tls_eecdh_grade)
              The Postfix tlsproxy(8) server security grade for ephemeral
              elliptic-curve Diffie-Hellman (EECDH) key exchange.

       tlsproxy_tls_exclude_ciphers ($smtpd_tls_exclude_ciphers)
              List of ciphers or cipher types to exclude from the tlsproxy(8)
              server cipher list at all TLS security levels.

       tlsproxy_tls_fingerprint_digest ($smtpd_tls_fingerprint_digest)
              The message digest algorithm used to construct client-
              certificate fingerprints.

       tlsproxy_tls_key_file ($smtpd_tls_key_file)
              File with the Postfix tlsproxy(8) server RSA private key in PEM
              format.

       tlsproxy_tls_loglevel ($smtpd_tls_loglevel)
              Enable additional Postfix tlsproxy(8) server logging of TLS
              activity.

       tlsproxy_tls_mandatory_ciphers ($smtpd_tls_mandatory_ciphers)
              The minimum TLS cipher grade that the Postfix tlsproxy(8) server
              will use with mandatory TLS encryption.

       tlsproxy_tls_mandatory_exclude_ciphers
              ($smtpd_tls_mandatory_exclude_ciphers)
              Additional list of ciphers or cipher types to exclude from the
              tlsproxy(8) server cipher list at mandatory TLS security levels.

       tlsproxy_tls_mandatory_protocols ($smtpd_tls_mandatory_protocols)
              The SSL/TLS protocols accepted by the Postfix tlsproxy(8) server
              with mandatory TLS encryption.

       tlsproxy_tls_protocols ($smtpd_tls_protocols)
              List of TLS protocols that the Postfix tlsproxy(8) server will
              exclude or include with opportunistic TLS encryption.

       tlsproxy_tls_req_ccert ($smtpd_tls_req_ccert)
              With mandatory TLS encryption, require a trusted remote SMTP
              client certificate in order to allow TLS connections to proceed.

       tlsproxy_tls_security_level ($smtpd_tls_security_level)
              The SMTP TLS security level for the Postfix tlsproxy(8) server;
              when a non-empty value is specified, this overrides the obsolete
              parameters smtpd_use_tls and smtpd_enforce_tls.

       tlsproxy_tls_session_cache_timeout ($smtpd_tls_session_cache_timeout)
              The expiration time of Postfix tlsproxy(8) server TLS session
              cache information.

OBSOLETE STARTTLS SUPPORT CONTROLS
       These parameters are supported for compatibility with smtpd(8) legacy
       parameters.

       tlsproxy_use_tls ($smtpd_use_tls)
              Opportunistic TLS: announce STARTTLS support to SMTP clients,
              but do not require that clients use TLS encryption.

       tlsproxy_enforce_tls ($smtpd_enforce_tls)
              Mandatory TLS: announce STARTTLS support to SMTP clients, and
              require that clients use TLS encryption.

RESOURCE CONTROLS

       tlsproxy_watchdog_timeout (10s)
              How much time a tlsproxy(8) process may take to process local or
              remote I/O before it is terminated by a built-in watchdog timer.

MISCELLANEOUS CONTROLS

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

       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
       postscreen(8), Postfix zombie blocker
       smtpd(8), Postfix SMTP server
       postconf(5), configuration parameters
       syslogd(5), system logging

LICENSE
       The Secure Mailer license must be distributed with this software.

HISTORY
       This service was introduced with Postfix version 2.8.

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



                                                                   TLSPROXY(8)