tls

This plugin enables the use of TLS (via STARTTLS) in Haraka.

For this plugin to work you must have SSL certificates installed correctly.

Certificate Files

Defaults are shown and can be overridden in config/tls.ini.

key=tls_key.pem
cert=tls_cert.pem
dhparam=dhparams.pem

Certificate Directory

If the directory config/tls exists, each file within the directory is expected to be a PEM encoded TLS bundle. Generate the PEM bundles in The Usual Way[TM] by concatenating the key, certificate, and CA/chain certs in that order. Example:

cat example.com.key example.com.crt ca.crt > config/tls/example.com.pem

An example acme.sh deployment script demonstrates how to install Let’s Encrypt certificates to the Haraka config/tlsdirectory.

Haraka has SNI support. When the remote MUA/MTA presents a servername during the TLS handshake and a TLS certificate with that Common Name matches, that certificate will be presented. If no match is found, the default certificate (see Certificate Files above) is presented.

Purchased Certificate

If you have a purchased certificate, append any intermediate/chained/ca-cert files to the certificate in this order:

  1. The CA signed SSL cert
  2. Any intermediate certificates
  3. The CA root certificate

See also Setting Up TLS

Self Issued (unsigned) Certificate

Create a certificate and key file in the config directory with the following command:

openssl req -x509 -nodes -days 2190 -newkey rsa:2048 \
        -keyout config/tls_key.pem -out config/tls_cert.pem

You will be prompted to provide details of your organization. Make sure the Common Name is set to your servers Fully Qualified Domain Name, which should be the same as the contents of your config/me file.

Configuration

The following settings can be specified in config/tls.ini.

key

Specifies an alternative location for the key file. For multiple keys, use key[]= assignment for each. Non-absolute paths are relative to the config/ directory.

To configure a single key and a cert chain, located in the config/ directory, use the following in tls.ini:

key=example.com.key.pem
cert=example.com.crt-chain.pem

To use multiple pairs of key and cert chain files outside of the haraka config/ directory, configure instead:

key[]=/etc/ssl/private/example.com.rsa.key.pem
cert[]=/etc/ssl/private/example.com.rsa.crt-chain.pem
key[]=/etc/ssl/private/example.com.ecdsa.key.pem
cert[]=/etc/ssl/private/example.com.ecdsa.crt-chain.pem

cert

Specifies the location(s) for the certificate chain file. For multiple certificate chains, use cert[]= assignment for each. Non-absolute paths are relative to the config/ directory. See the description of the key parameter for specific use.

no_tls_hosts

If needed, add this section to the config/tls.ini file and list any IP ranges that have broken TLS hosts. Ex:

[no_tls_hosts]
192.168.1.3
172.16.0.0/16

The Node.js TLS page has additional information about the following options.

ciphers

A list of allowable ciphers to use. Example:

ciphers=EECDH+AESGCM:EDH+aRSA+AESGCM:EECDH+AES256:EDH+aRSA+AES256:EECDH+AES128:EDH+aRSA+AES128:RSA+AES:RSA+3DES

See also: Strong SSL Ciphers and the SSLlabs Test Page

honorCipherOrder

If specified, the list of configured ciphers is treated as the cipher priority from highest to lowest. The first matching cipher will be used, instead of letting the client choose. The default is true.

ecdhCurve

Specifies the elliptic curve used for ECDH or ECDHE ciphers. Only one curve can be specified. The default is prime256v1 (NIST P-256).

dhparam

Specifies the file containing the diffie-hellman parameters to use for DH or DHE key exchange. If this param or file is missing, it will be generated automatically. Default: dhparams.pem.

requestCert

Whether Haraka should request a certificate from a connecting client.

requestCert=[true|false]  (default: true)

rejectUnauthorized

Reject connections from clients without a CA validated TLS certificate.

rejectUnauthorized=[true|false]  (default: false)

requireAuthorized

When rejectUnauthorized=false, require validated TLS certificates on just the specified ports.

requireAuthorized[]=465
;requireAuthorized[]=587

secureProtocol

Specifies the OpenSSL API function used for handling the TLS session. Choose one of the methods described at the OpenSSL API page. The default is SSLv23_method.

requestOCSP

Specifies that OCSP Stapling should be enabled, according to RFC 6066. Stapling of OCSP messages allows the client to receive these along the TLS session setup instead of delaying the session setup by requiring a separate http connection to the OCSP server.

requestOCSP=[true|false]  (default: false)

OCSP responses from the OCSP server are cached in memory for as long as they are valid, and get refreshed after that time. A server restart requires the OCSP responses to be fetched again upon the first client connection.

Inbound Specific Configuration

By default the above options are shared with outbound mail (either using smtp_forward, smtp_proxy or plain outbound mail heading to an external destination). To make these options specific to inbound mail, put them under an [inbound] parameter group. Outbound options can go under an [outbound] parameter group, and plugins that use SMTP tls for queueing such as smtp_proxy and smtp_forward can use that plugin name for plugin specific options.