Provided by: postfix_3.1.0-3ubuntu0.4_amd64 
NAME
postfix-tls - Postfix TLS management
SYNOPSIS
postfix tls subcommand
DESCRIPTION
The "postfix tls subcommand" feature enables opportunistic TLS in the Postfix SMTP client or server, and
manages Postfix SMTP server private keys and certificates.
The following subcommands are available:
enable-client [-r randsource]
Enable opportunistic TLS in the Postfix SMTP client, if all SMTP client TLS settings are at their
default values. Otherwise, suggest parameter settings without making any changes.
Specify randsource to update the value of the tls_random_source configuration parameter
(typically, /dev/urandom). Prepend dev: to device paths or egd: to EGD socket paths.
See also the all-default-client subcommand.
enable-server [-r randsource] [-a algorithm] [-b bits] [hostname...]
Create a new private key and self-signed server certificate and enable opportunistic TLS in the
Postfix SMTP server, if all SMTP server TLS settings are at their default values. Otherwise,
suggest parameter settings without making any changes.
The randsource parameter is as with enable-client above, and the remaining options are as with
new-server-key below.
See also the all-default-server subcommand.
new-server-key [-a algorithm] [-b bits] [hostname...]
Create a new private key and self-signed server certificate, but do not deploy them. Log and
display commands to deploy the new key and corresponding certificate. Also log and display
commands to output a corresponding CSR or TLSA records which may be needed to obtain a CA
certificate or to update DNS before the new key can be deployed.
The algorithm defaults to rsa, and bits defaults to 2048. If you choose the ecdsa algorithm then
bits will be an EC curve name (by default secp256r1, also known as prime256v1). Curves other than
secp256r1, secp384r1 or secp521r1 are unlikely to be widely interoperable. When generating EC
keys, use one of these three. DSA keys are obsolete and are not supported.
Note: ECDSA support requires OpenSSL 1.0.0 or later and may not be available on your system. Not
all client systems will support ECDSA, so you'll generally want to deploy both RSA and ECDSA
certificates to make use of ECDSA with compatible clients and RSA with the rest. If you want to
deploy certificate chains with intermediate CAs for both RSA and ECDSA, you'll want at least
OpenSSL 1.0.2, as earlier versions may not handle multiple chain files correctly.
The first hostname argument will be the CommonName of both the subject and issuer of the
self-signed certificate. It, and any additional hostname arguments, will also be listed as DNS
alternative names in the certificate. If no hostname is provided the value of the myhostname
main.cf parameter will be used.
For RSA, the generated private key and certificate files are named key-yyyymmdd-hhmmss.pem and
cert-yyyymmdd-hhmmss.pem, where yyyymmdd is the calendar date and hhmmss is the time of day in
UTC. For ECDSA, the file names start with eckey- and eccert- instead of key- and cert-
respectively.
Before deploying the new key and certificate with DANE, update the DNS with new DANE TLSA records,
then wait for secondary nameservers to update and then for stale records in remote DNS caches to
expire.
Before deploying a new CA certificate make sure to include all the required intermediate issuing
CA certificates in the certificate chain file. The server certificate must be the first
certificate in the chain file. Overwrite and deploy the file with the original self-signed
certificate that was generated together with the key.
new-server-cert [-a algorithm] [-b bits] [hostname...]
This is just like new-server-key except that, rather than generating a new private key, any
currently deployed private key is copied to the new key file. Thus if you're publishing DANE TLSA
"3 1 1" or "3 1 2" records, there is no need to update DNS records. The algorithm and bits
arguments are used only if no key of the same algorithm is already configured.
This command is rarely needed, because the self-signed certificates generated have a 100-year
nominal expiration time. The underlying public key algorithms may well be obsoleted by quantum
computers long before then.
The most plausible reason for using this command is when the system hostname changes, and you'd
like the name in the certificate to match the new hostname (not required for DANE "3 1 1", but
some needlessly picky non-DANE opportunistic TLS clients may log warnings or even refuse to
communicate).
deploy-server-cert certfile keyfile
This subcommand deploys the certificates in certfile and private key in keyfile (which are
typically generated by the commands above, which will also log and display the full command needed
to deploy the generated key and certificate). After the new certificate and key are deployed any
obsolete keys and certificates may be removed by hand. The keyfile and certfile filenames may be
relative to the Postfix configuration directory.
output-server-csr [-k keyfile] [hostname...]
Write to stdout a certificate signing request (CSR) for the specified keyfile.
Instead of an absolute pathname or a pathname relative to $config_directory, keyfile may specify
one of the supported key algorithm names (see "postconf -T public-key-algorithms"). In that case,
the corresponding setting from main.cf is used to locate the keyfile. The default keyfile value
is rsa.
Zero or more hostname values can be specified. The default hostname is the value of myhostname
main.cf parameter.
output-server-tlsa [-h hostname] [keyfile...]
Write to stdout a DANE TLSA RRset suitable for a port 25 SMTP server on host hostname with keys
from any of the specified keyfile values. The default hostname is the value of the myhostname
main.cf parameter.
Instead of absolute pathnames or pathnames relative to $config_directory, the keyfile list may
specify names of supported public key algorithms (see "postconf -T public-key-algorithms"). In
that case, the actual keyfile list uses the values of the corresponding Postfix server TLS key
file parameters. If a parameter value is empty or equal to none, then no TLSA record is output
for that algorithm.
The default keyfile list consists of the two supported algorithms rsa and ecdsa.
AUXILIARY COMMANDS
all-default-client
Exit with status 0 (success) if all SMTP client TLS settings are
at their default values. Otherwise, exit with a non-zero status.
This is typically used as follows:
postfix tls all-default-client &&
postfix tls enable-tls-client
all-default-server
Exit with status 0 (success) if all SMTP server TLS settings are
at their default values. Otherwise, exit with a non-zero status.
This is typically used as follows:
postfix tls all-default-server &&
postfix tls enable-tls-server
CONFIGURATION PARAMETERS
The "postfix tls subcommand" feature reads or updates the following configuration parameters.
command_directory (see 'postconf -d' output)
The location of all postfix administrative commands.
config_directory (see 'postconf -d' output)
The default location of the Postfix main.cf and master.cf configuration files.
openssl_path (openssl)
The location of the OpenSSL command line program openssl(1).
smtp_tls_loglevel (0)
Enable additional Postfix SMTP client logging of TLS activity.
smtp_tls_security_level (empty)
The default SMTP TLS security level for the Postfix SMTP client; when a non-empty value is
specified, this overrides the obsolete parameters smtp_use_tls, smtp_enforce_tls, and
smtp_tls_enforce_peername.
smtp_tls_session_cache_database (empty)
Name of the file containing the optional Postfix SMTP client TLS session cache.
smtpd_tls_cert_file (empty)
File with the Postfix SMTP server RSA certificate in PEM format.
smtpd_tls_eccert_file (empty)
File with the Postfix SMTP server ECDSA certificate in PEM format.
smtpd_tls_eckey_file ($smtpd_tls_eccert_file)
File with the Postfix SMTP server ECDSA private key in PEM format.
smtpd_tls_key_file ($smtpd_tls_cert_file)
File with the Postfix SMTP server RSA private key in PEM format.
smtpd_tls_loglevel (0)
Enable additional Postfix SMTP server logging of TLS activity.
smtpd_tls_received_header (no)
Request that the Postfix SMTP server produces Received: message headers that include information
about the protocol and cipher used, as well as the remote SMTP client CommonName and client
certificate issuer CommonName.
smtpd_tls_security_level (empty)
The SMTP TLS security level for the Postfix SMTP server; when a non-empty value is specified, this
overrides the obsolete parameters smtpd_use_tls and smtpd_enforce_tls.
tls_random_source (see 'postconf -d' output)
The external entropy source for the in-memory tlsmgr(8) pseudo random number generator (PRNG)
pool.
SEE ALSO
master(8) Postfix master program postfix(1) Postfix administrative interface
README FILES
Use "postconf readme_directory" or "postconf html_directory" to locate this information.
TLS_README, Postfix TLS configuration and operation
LICENSE
The Secure Mailer license must be distributed with this software.
HISTORY
The "postfix tls" command was introduced with Postfix version 3.1.
AUTHOR(S)
Viktor Dukhovni
POSTFIX-TLS(1)