Postfix manual - tlsproxy(8)

    TLSPROXY(8)                                                        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  that
           are  not  whitelisted  (including  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 eas-
           ily adapted to other applications.

           After receiving a  valid  remote  SMTP  client  STARTTLS  command,  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 plain-
           text 220 greeting to the remote SMTP client.  This triggers TLS negoti-
           ations 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) pro-
           cesses 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 inter-
                  mediate 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 inter-
                  mediate CA certificates.

           tlsproxy_tls_always_issue_session_ids     ($smtpd_tls_always_issue_ses-
           sion_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 non-export 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 export-grade 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   to  construct  remote  SMTP
                  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_manda-
           tory_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.

           Available in Postfix version 2.11 and later:

           tlsmgr_service_name (tlsmgr)
                  The name of the tlsmgr(8) service entry in master.cf.

    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  remote  SMTP
                  clients, but do not require that clients use TLS encryption.

           tlsproxy_enforce_tls ($smtpd_enforce_tls)
                  Mandatory TLS: announce STARTTLS support to remote 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  con-
                  figuration 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,  "post-
                  fix/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)