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TLSPROXY(8) TLSPROXY(8)
<b>NAME</b>
tlsproxy - Postfix TLS proxy
<b>SYNOPSIS</b>
<b>tlsproxy</b> [generic Postfix daemon options]
<b>DESCRIPTION</b>
The <a href="tlsproxy.8.html"><b>tlsproxy</b>(8)</a> server implements a server-side TLS proxy. It is used
by <a href="postscreen.8.html"><b>postscreen</b>(8)</a> 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 <a href="tlsproxy.8.html"><b>tlsproxy</b>(8)</a> 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.
<b>PROTOCOL EXAMPLE</b>
The example below concerns <a href="postscreen.8.html"><b>postscreen</b>(8)</a>. However, the <a href="tlsproxy.8.html"><b>tlsproxy</b>(8)</a>
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
<a href="postscreen.8.html"><b>postscreen</b>(8)</a> server sends the remote SMTP client endpoint string, the
requested role (server), and the requested timeout to <a href="tlsproxy.8.html"><b>tlsproxy</b>(8)</a>.
<a href="postscreen.8.html"><b>postscreen</b>(8)</a> then receives a "TLS available" indication from
<a href="tlsproxy.8.html"><b>tlsproxy</b>(8)</a>. If the TLS service is available, <a href="postscreen.8.html"><b>postscreen</b>(8)</a> sends the
remote SMTP client file descriptor to <a href="tlsproxy.8.html"><b>tlsproxy</b>(8)</a>, and sends the plain-
text 220 greeting to the remote SMTP client. This triggers TLS negoti-
ations between the remote SMTP client and <a href="tlsproxy.8.html"><b>tlsproxy</b>(8)</a>. Upon completion
of the TLS-level handshake, <a href="tlsproxy.8.html"><b>tlsproxy</b>(8)</a> translates between plaintext
from/to <a href="postscreen.8.html"><b>postscreen</b>(8)</a> and ciphertext to/from the remote SMTP client.
<b>SECURITY</b>
The <a href="tlsproxy.8.html"><b>tlsproxy</b>(8)</a> server is moderately security-sensitive. It talks to
untrusted clients on the network. The process can be run chrooted at
fixed low privilege.
<b>DIAGNOSTICS</b>
Problems and transactions are logged to <b>syslogd</b>(8).
<b>CONFIGURATION PARAMETERS</b>
Changes to <a href="postconf.5.html"><b>main.cf</b></a> are not picked up automatically, as <a href="tlsproxy.8.html"><b>tlsproxy</b>(8)</a> pro-
cesses may run for a long time depending on mail server load. Use the
command "<b>postfix reload</b>" to speed up a change.
The text below provides only a parameter summary. See <a href="postconf.5.html"><b>postconf</b>(5)</a> for
more details including examples.
<b>STARTTLS SUPPORT CONTROLS</b>
<b><a href="postconf.5.html#tlsproxy_tls_CAfile">tlsproxy_tls_CAfile</a> ($<a href="postconf.5.html#smtpd_tls_CAfile">smtpd_tls_CAfile</a>)</b>
A file containing (PEM format) CA certificates of root CAs
trusted to sign either remote SMTP client certificates or inter-
mediate CA certificates.
<b><a href="postconf.5.html#tlsproxy_tls_CApath">tlsproxy_tls_CApath</a> ($<a href="postconf.5.html#smtpd_tls_CApath">smtpd_tls_CApath</a>)</b>
A directory containing (PEM format) CA certificates of root CAs
trusted to sign either remote SMTP client certificates or inter-
mediate CA certificates.
<b><a href="postconf.5.html#tlsproxy_tls_always_issue_session_ids">tlsproxy_tls_always_issue_session_ids</a> ($<a href="postconf.5.html#smtpd_tls_always_issue_session_ids">smtpd_tls_always_issue_ses</a>-</b>
<b><a href="postconf.5.html#smtpd_tls_always_issue_session_ids">sion_ids</a>)</b>
Force the Postfix <a href="tlsproxy.8.html"><b>tlsproxy</b>(8)</a> server to issue a TLS session id,
even when TLS session caching is turned off.
<b><a href="postconf.5.html#tlsproxy_tls_ask_ccert">tlsproxy_tls_ask_ccert</a> ($<a href="postconf.5.html#smtpd_tls_ask_ccert">smtpd_tls_ask_ccert</a>)</b>
Ask a remote SMTP client for a client certificate.
<b><a href="postconf.5.html#tlsproxy_tls_ccert_verifydepth">tlsproxy_tls_ccert_verifydepth</a> ($<a href="postconf.5.html#smtpd_tls_ccert_verifydepth">smtpd_tls_ccert_verifydepth</a>)</b>
The verification depth for remote SMTP client certificates.
<b><a href="postconf.5.html#tlsproxy_tls_cert_file">tlsproxy_tls_cert_file</a> ($<a href="postconf.5.html#smtpd_tls_cert_file">smtpd_tls_cert_file</a>)</b>
File with the Postfix <a href="tlsproxy.8.html"><b>tlsproxy</b>(8)</a> server RSA certificate in PEM
format.
<b><a href="postconf.5.html#tlsproxy_tls_ciphers">tlsproxy_tls_ciphers</a> ($<a href="postconf.5.html#smtpd_tls_ciphers">smtpd_tls_ciphers</a>)</b>
The minimum TLS cipher grade that the Postfix <a href="tlsproxy.8.html"><b>tlsproxy</b>(8)</a> server
will use with opportunistic TLS encryption.
<b><a href="postconf.5.html#tlsproxy_tls_dcert_file">tlsproxy_tls_dcert_file</a> ($<a href="postconf.5.html#smtpd_tls_dcert_file">smtpd_tls_dcert_file</a>)</b>
File with the Postfix <a href="tlsproxy.8.html"><b>tlsproxy</b>(8)</a> server DSA certificate in PEM
format.
<b><a href="postconf.5.html#tlsproxy_tls_dh1024_param_file">tlsproxy_tls_dh1024_param_file</a> ($<a href="postconf.5.html#smtpd_tls_dh1024_param_file">smtpd_tls_dh1024_param_file</a>)</b>
File with DH parameters that the Postfix <a href="tlsproxy.8.html"><b>tlsproxy</b>(8)</a> server
should use with non-export EDH ciphers.
<b><a href="postconf.5.html#tlsproxy_tls_dh512_param_file">tlsproxy_tls_dh512_param_file</a> ($<a href="postconf.5.html#smtpd_tls_dh512_param_file">smtpd_tls_dh512_param_file</a>)</b>
File with DH parameters that the Postfix <a href="tlsproxy.8.html"><b>tlsproxy</b>(8)</a> server
should use with export-grade EDH ciphers.
<b><a href="postconf.5.html#tlsproxy_tls_dkey_file">tlsproxy_tls_dkey_file</a> ($<a href="postconf.5.html#smtpd_tls_dkey_file">smtpd_tls_dkey_file</a>)</b>
File with the Postfix <a href="tlsproxy.8.html"><b>tlsproxy</b>(8)</a> server DSA private key in PEM
format.
<b><a href="postconf.5.html#tlsproxy_tls_eccert_file">tlsproxy_tls_eccert_file</a> ($<a href="postconf.5.html#smtpd_tls_eccert_file">smtpd_tls_eccert_file</a>)</b>
File with the Postfix <a href="tlsproxy.8.html"><b>tlsproxy</b>(8)</a> server ECDSA certificate in
PEM format.
<b><a href="postconf.5.html#tlsproxy_tls_eckey_file">tlsproxy_tls_eckey_file</a> ($<a href="postconf.5.html#smtpd_tls_eckey_file">smtpd_tls_eckey_file</a>)</b>
File with the Postfix <a href="tlsproxy.8.html"><b>tlsproxy</b>(8)</a> server ECDSA private key in
PEM format.
<b><a href="postconf.5.html#tlsproxy_tls_eecdh_grade">tlsproxy_tls_eecdh_grade</a> ($<a href="postconf.5.html#smtpd_tls_eecdh_grade">smtpd_tls_eecdh_grade</a>)</b>
The Postfix <a href="tlsproxy.8.html"><b>tlsproxy</b>(8)</a> server security grade for ephemeral
elliptic-curve Diffie-Hellman (EECDH) key exchange.
<b><a href="postconf.5.html#tlsproxy_tls_exclude_ciphers">tlsproxy_tls_exclude_ciphers</a> ($<a href="postconf.5.html#smtpd_tls_exclude_ciphers">smtpd_tls_exclude_ciphers</a>)</b>
List of ciphers or cipher types to exclude from the <a href="tlsproxy.8.html"><b>tlsproxy</b>(8)</a>
server cipher list at all TLS security levels.
<b><a href="postconf.5.html#tlsproxy_tls_fingerprint_digest">tlsproxy_tls_fingerprint_digest</a> ($<a href="postconf.5.html#smtpd_tls_fingerprint_digest">smtpd_tls_fingerprint_digest</a>)</b>
The message digest algorithm to construct remote SMTP
client-certificate fingerprints.
<b><a href="postconf.5.html#tlsproxy_tls_key_file">tlsproxy_tls_key_file</a> ($<a href="postconf.5.html#smtpd_tls_key_file">smtpd_tls_key_file</a>)</b>
File with the Postfix <a href="tlsproxy.8.html"><b>tlsproxy</b>(8)</a> server RSA private key in PEM
format.
<b><a href="postconf.5.html#tlsproxy_tls_loglevel">tlsproxy_tls_loglevel</a> ($<a href="postconf.5.html#smtpd_tls_loglevel">smtpd_tls_loglevel</a>)</b>
Enable additional Postfix <a href="tlsproxy.8.html"><b>tlsproxy</b>(8)</a> server logging of TLS
activity.
<b><a href="postconf.5.html#tlsproxy_tls_mandatory_ciphers">tlsproxy_tls_mandatory_ciphers</a> ($<a href="postconf.5.html#smtpd_tls_mandatory_ciphers">smtpd_tls_mandatory_ciphers</a>)</b>
The minimum TLS cipher grade that the Postfix <a href="tlsproxy.8.html"><b>tlsproxy</b>(8)</a> server
will use with mandatory TLS encryption.
<b><a href="postconf.5.html#tlsproxy_tls_mandatory_exclude_ciphers">tlsproxy_tls_mandatory_exclude_ciphers</a> ($<a href="postconf.5.html#smtpd_tls_mandatory_exclude_ciphers">smtpd_tls_manda</a>-</b>
<b><a href="postconf.5.html#smtpd_tls_mandatory_exclude_ciphers">tory_exclude_ciphers</a>)</b>
Additional list of ciphers or cipher types to exclude from the
<a href="tlsproxy.8.html"><b>tlsproxy</b>(8)</a> server cipher list at mandatory TLS security levels.
<b><a href="postconf.5.html#tlsproxy_tls_mandatory_protocols">tlsproxy_tls_mandatory_protocols</a> ($<a href="postconf.5.html#smtpd_tls_mandatory_protocols">smtpd_tls_mandatory_protocols</a>)</b>
The SSL/TLS protocols accepted by the Postfix <a href="tlsproxy.8.html"><b>tlsproxy</b>(8)</a> server
with mandatory TLS encryption.
<b><a href="postconf.5.html#tlsproxy_tls_protocols">tlsproxy_tls_protocols</a> ($<a href="postconf.5.html#smtpd_tls_protocols">smtpd_tls_protocols</a>)</b>
List of TLS protocols that the Postfix <a href="tlsproxy.8.html"><b>tlsproxy</b>(8)</a> server will
exclude or include with opportunistic TLS encryption.
<b><a href="postconf.5.html#tlsproxy_tls_req_ccert">tlsproxy_tls_req_ccert</a> ($<a href="postconf.5.html#smtpd_tls_req_ccert">smtpd_tls_req_ccert</a>)</b>
With mandatory TLS encryption, require a trusted remote SMTP
client certificate in order to allow TLS connections to proceed.
<b><a href="postconf.5.html#tlsproxy_tls_security_level">tlsproxy_tls_security_level</a> ($<a href="postconf.5.html#smtpd_tls_security_level">smtpd_tls_security_level</a>)</b>
The SMTP TLS security level for the Postfix <a href="tlsproxy.8.html"><b>tlsproxy</b>(8)</a> server;
when a non-empty value is specified, this overrides the obsolete
parameters <a href="postconf.5.html#smtpd_use_tls">smtpd_use_tls</a> and <a href="postconf.5.html#smtpd_enforce_tls">smtpd_enforce_tls</a>.
Available in Postfix version 2.11 and later:
<b><a href="postconf.5.html#tlsmgr_service_name">tlsmgr_service_name</a> (tlsmgr)</b>
The name of the <a href="tlsmgr.8.html"><b>tlsmgr</b>(8)</a> service entry in <a href="master.5.html">master.cf</a>.
<b>OBSOLETE STARTTLS SUPPORT CONTROLS</b>
These parameters are supported for compatibility with <a href="smtpd.8.html"><b>smtpd</b>(8)</a> legacy
parameters.
<b><a href="postconf.5.html#tlsproxy_use_tls">tlsproxy_use_tls</a> ($<a href="postconf.5.html#smtpd_use_tls">smtpd_use_tls</a>)</b>
Opportunistic TLS: announce STARTTLS support to remote SMTP
clients, but do not require that clients use TLS encryption.
<b><a href="postconf.5.html#tlsproxy_enforce_tls">tlsproxy_enforce_tls</a> ($<a href="postconf.5.html#smtpd_enforce_tls">smtpd_enforce_tls</a>)</b>
Mandatory TLS: announce STARTTLS support to remote SMTP clients,
and require that clients use TLS encryption.
<b>RESOURCE CONTROLS</b>
<b><a href="postconf.5.html#tlsproxy_watchdog_timeout">tlsproxy_watchdog_timeout</a> (10s)</b>
How much time a <a href="tlsproxy.8.html"><b>tlsproxy</b>(8)</a> process may take to process local or
remote I/O before it is terminated by a built-in watchdog timer.
<b>MISCELLANEOUS CONTROLS</b>
<b><a href="postconf.5.html#config_directory">config_directory</a> (see 'postconf -d' output)</b>
The default location of the Postfix <a href="postconf.5.html">main.cf</a> and <a href="master.5.html">master.cf</a> con-
figuration files.
<b><a href="postconf.5.html#process_id">process_id</a> (read-only)</b>
The process ID of a Postfix command or daemon process.
<b><a href="postconf.5.html#process_name">process_name</a> (read-only)</b>
The process name of a Postfix command or daemon process.
<b><a href="postconf.5.html#syslog_facility">syslog_facility</a> (mail)</b>
The syslog facility of Postfix logging.
<b><a href="postconf.5.html#syslog_name">syslog_name</a> (see 'postconf -d' output)</b>
The mail system name that is prepended to the process name in
syslog records, so that "smtpd" becomes, for example, "post-
fix/smtpd".
<b>SEE ALSO</b>
<a href="postscreen.8.html">postscreen(8)</a>, Postfix zombie blocker
<a href="smtpd.8.html">smtpd(8)</a>, Postfix SMTP server
<a href="postconf.5.html">postconf(5)</a>, configuration parameters
syslogd(5), system logging
<b>LICENSE</b>
The Secure Mailer license must be distributed with this software.
<b>HISTORY</b>
This service was introduced with Postfix version 2.8.
<b>AUTHOR(S)</b>
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
TLSPROXY(8)
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