~ubuntu-branches/ubuntu/trusty/postfix/trusty-updates

.TH TLSPROXY 8 

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.SH NAME

tlsproxy

\-

Postfix TLS proxy

.SH "SYNOPSIS"

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\fBtlsproxy\fR [generic Postfix daemon options]

.SH DESCRIPTION

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The \fBtlsproxy\fR(8) server implements a server-side TLS

proxy. It is used by \fBpostscreen\fR(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 \fBtlsproxy\fR(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.

.SH "PROTOCOL EXAMPLE"

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The example below concerns \fBpostscreen\fR(8). However,

the \fBtlsproxy\fR(8) server is agnostic of the application

protocol, and the example is easily adapted to other

applications.

After receiving a valid remote SMTP client STARTTLS command,

the \fBpostscreen\fR(8) server sends the remote SMTP client

endpoint string, the requested role (server), and the

requested timeout to \fBtlsproxy\fR(8).  \fBpostscreen\fR(8)

then receives a "TLS available" indication from \fBtlsproxy\fR(8).

If the TLS service is available, \fBpostscreen\fR(8) sends

the remote SMTP client file descriptor to \fBtlsproxy\fR(8),

and sends the plaintext 220 greeting to the remote SMTP

client.  This triggers TLS negotiations between the remote

SMTP client and \fBtlsproxy\fR(8).  Upon completion of the

TLS-level handshake, \fBtlsproxy\fR(8) translates between

plaintext from/to \fBpostscreen\fR(8) and ciphertext to/from

the remote SMTP client.

.SH "SECURITY"

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The \fBtlsproxy\fR(8) server is moderately security-sensitive.

It talks to untrusted clients on the network. The process

can be run chrooted at fixed low privilege.

.SH DIAGNOSTICS

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Problems and transactions are logged to \fBsyslogd\fR(8).

.SH "CONFIGURATION PARAMETERS"

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Changes to \fBmain.cf\fR are not picked up automatically,

as \fBtlsproxy\fR(8) processes may run for a long time

depending on mail server load.  Use the command "\fBpostfix

reload\fR" to speed up a change.

The text below provides only a parameter summary. See

\fBpostconf\fR(5) for more details including examples.

.SH "STARTTLS SUPPORT CONTROLS"

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.IP "\fBtlsproxy_tls_CAfile ($smtpd_tls_CAfile)\fR"

A file containing (PEM format) CA certificates of root CAs

trusted to sign either remote SMTP client certificates or intermediate

CA certificates.

.IP "\fBtlsproxy_tls_CApath ($smtpd_tls_CApath)\fR"

A directory containing (PEM format) CA certificates of root CAs

trusted to sign either remote SMTP client certificates or intermediate

CA certificates.

.IP "\fBtlsproxy_tls_always_issue_session_ids ($smtpd_tls_always_issue_session_ids)\fR"

Force the Postfix \fBtlsproxy\fR(8) server to issue a TLS session id,

even when TLS session caching is turned off.

.IP "\fBtlsproxy_tls_ask_ccert ($smtpd_tls_ask_ccert)\fR"

Ask a remote SMTP client for a client certificate.

.IP "\fBtlsproxy_tls_ccert_verifydepth ($smtpd_tls_ccert_verifydepth)\fR"

The verification depth for remote SMTP client certificates.

.IP "\fBtlsproxy_tls_cert_file ($smtpd_tls_cert_file)\fR"

File with the Postfix \fBtlsproxy\fR(8) server RSA certificate in PEM

format.

.IP "\fBtlsproxy_tls_ciphers ($smtpd_tls_ciphers)\fR"

The minimum TLS cipher grade that the Postfix \fBtlsproxy\fR(8) server

will use with opportunistic TLS encryption.

.IP "\fBtlsproxy_tls_dcert_file ($smtpd_tls_dcert_file)\fR"

File with the Postfix \fBtlsproxy\fR(8) server DSA certificate in PEM

format.

.IP "\fBtlsproxy_tls_dh1024_param_file ($smtpd_tls_dh1024_param_file)\fR"

File with DH parameters that the Postfix \fBtlsproxy\fR(8) server

should use with non-export EDH ciphers.

.IP "\fBtlsproxy_tls_dh512_param_file ($smtpd_tls_dh512_param_file)\fR"

File with DH parameters that the Postfix \fBtlsproxy\fR(8) server

should use with export-grade EDH ciphers.

.IP "\fBtlsproxy_tls_dkey_file ($smtpd_tls_dkey_file)\fR"

File with the Postfix \fBtlsproxy\fR(8) server DSA private key in PEM

format.

.IP "\fBtlsproxy_tls_eccert_file ($smtpd_tls_eccert_file)\fR"

File with the Postfix \fBtlsproxy\fR(8) server ECDSA certificate in

PEM format.

.IP "\fBtlsproxy_tls_eckey_file ($smtpd_tls_eckey_file)\fR"

File with the Postfix \fBtlsproxy\fR(8) server ECDSA private key in

PEM format.

.IP "\fBtlsproxy_tls_eecdh_grade ($smtpd_tls_eecdh_grade)\fR"

The Postfix \fBtlsproxy\fR(8) server security grade for ephemeral

elliptic-curve Diffie-Hellman (EECDH) key exchange.

.IP "\fBtlsproxy_tls_exclude_ciphers ($smtpd_tls_exclude_ciphers)\fR"

List of ciphers or cipher types to exclude from the \fBtlsproxy\fR(8)

server cipher list at all TLS security levels.

.IP "\fBtlsproxy_tls_fingerprint_digest ($smtpd_tls_fingerprint_digest)\fR"

The message digest algorithm to construct remote SMTP

client-certificate

fingerprints.

.IP "\fBtlsproxy_tls_key_file ($smtpd_tls_key_file)\fR"

File with the Postfix \fBtlsproxy\fR(8) server RSA private key in PEM

format.

.IP "\fBtlsproxy_tls_loglevel ($smtpd_tls_loglevel)\fR"

Enable additional Postfix \fBtlsproxy\fR(8) server logging of TLS

activity.

.IP "\fBtlsproxy_tls_mandatory_ciphers ($smtpd_tls_mandatory_ciphers)\fR"

The minimum TLS cipher grade that the Postfix \fBtlsproxy\fR(8) server

will use with mandatory TLS encryption.

.IP "\fBtlsproxy_tls_mandatory_exclude_ciphers ($smtpd_tls_mandatory_exclude_ciphers)\fR"

Additional list of ciphers or cipher types to exclude from the

\fBtlsproxy\fR(8) server cipher list at mandatory TLS security levels.

.IP "\fBtlsproxy_tls_mandatory_protocols ($smtpd_tls_mandatory_protocols)\fR"

The SSL/TLS protocols accepted by the Postfix \fBtlsproxy\fR(8) server

with mandatory TLS encryption.

.IP "\fBtlsproxy_tls_protocols ($smtpd_tls_protocols)\fR"

List of TLS protocols that the Postfix \fBtlsproxy\fR(8) server will

exclude or include with opportunistic TLS encryption.

.IP "\fBtlsproxy_tls_req_ccert ($smtpd_tls_req_ccert)\fR"

With mandatory TLS encryption, require a trusted remote SMTP

client certificate in order to allow TLS connections to proceed.

.IP "\fBtlsproxy_tls_security_level ($smtpd_tls_security_level)\fR"

The SMTP TLS security level for the Postfix \fBtlsproxy\fR(8) server;

when a non-empty value is specified, this overrides the obsolete

parameters smtpd_use_tls and smtpd_enforce_tls.

.PP

Available in Postfix version 2.11 and later:

.IP "\fBtlsmgr_service_name (tlsmgr)\fR"

The name of the \fBtlsmgr\fR(8) service entry in master.cf.

.SH "OBSOLETE STARTTLS SUPPORT CONTROLS"

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These parameters are supported for compatibility with

\fBsmtpd\fR(8) legacy parameters.

.IP "\fBtlsproxy_use_tls ($smtpd_use_tls)\fR"

Opportunistic TLS: announce STARTTLS support to remote SMTP clients,

but do not require that clients use TLS encryption.

.IP "\fBtlsproxy_enforce_tls ($smtpd_enforce_tls)\fR"

Mandatory TLS: announce STARTTLS support to remote SMTP clients, and

require that clients use TLS encryption.

.SH "RESOURCE CONTROLS"

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.IP "\fBtlsproxy_watchdog_timeout (10s)\fR"

How much time a \fBtlsproxy\fR(8) process may take to process local

or remote I/O before it is terminated by a built-in watchdog timer.

.SH "MISCELLANEOUS CONTROLS"

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.IP "\fBconfig_directory (see 'postconf -d' output)\fR"

The default location of the Postfix main.cf and master.cf

configuration files.

.IP "\fBprocess_id (read-only)\fR"

The process ID of a Postfix command or daemon process.

.IP "\fBprocess_name (read-only)\fR"

The process name of a Postfix command or daemon process.

.IP "\fBsyslog_facility (mail)\fR"

The syslog facility of Postfix logging.

.IP "\fBsyslog_name (see 'postconf -d' output)\fR"

The mail system name that is prepended to the process name in syslog

records, so that "smtpd" becomes, for example, "postfix/smtpd".

.SH "SEE ALSO"

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postscreen(8), Postfix zombie blocker

smtpd(8), Postfix SMTP server

postconf(5), configuration parameters

syslogd(5), system logging

.SH "LICENSE"

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The Secure Mailer license must be distributed with this software.

.SH "HISTORY"

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This service was introduced with Postfix version 2.8.

.SH "AUTHOR(S)"

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Wietse Venema

IBM T.J. Watson Research

P.O. Box 704

Yorktown Heights, NY 10598, USA