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postfix [2018/10/28 21:01] steve [Virtual Domains and Aliases] |
postfix [2018/10/30 16:49] steve [Security] |
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| If creating a new ''/var/log/maillog'' you will need to restart your system logger **in addition** to postfix for it to populate. | If creating a new ''/var/log/maillog'' you will need to restart your system logger **in addition** to postfix for it to populate. | ||
| + | |||
| + | ==== Security ==== | ||
| + | |||
| + | Enable Postfix to use TLS if possible. Clients and servers that connect may use it. In ''main.cf'': | ||
| + | |||
| + | <code> | ||
| + | smtp_tls_security_level = may | ||
| + | smtpd_tls_security_level = may | ||
| + | </code> | ||
| + | |||
| + | If you have your own certs, enable those as well. In this case, the ''server.pem'' is the combination of the CRT PEM and the CA bundle PEM. Be sure to set the key to read-only for the root user as well. | ||
| + | |||
| + | <code> | ||
| + | cat beandog.crt.pem ca_bundle.pem > server.pem | ||
| + | </code> | ||
| + | |||
| + | <code> | ||
| + | smtpd_tls_cert_file = /etc/postfix/server.pem | ||
| + | smtpd_tls_key_file = /etc/postfix/server.key | ||
| + | </code> | ||
| + | |||
| + | Postfix can define which protocols and ciphers to ignore, and set the preferred order as well. Here, ignore TLSv1 and use stronger ciphers: | ||
| + | |||
| + | <code> | ||
| + | smtp_tls_ciphers = high | ||
| + | smtp_tls_mandatory_ciphers = high | ||
| + | smtp_tls_protocols = TLSv1.2, TLSv1.1, !TLSv1 | ||
| + | smtp_tls_mandatory_protocols = TLSv1.2, TLSv1.1, !TLSv1 | ||
| + | |||
| + | smtpd_tls_ciphers = high | ||
| + | smtpd_tls_mandatory_ciphers = high | ||
| + | smtpd_tls_protocols = TLSv1.2, TLSv1.1, !TLSv1 | ||
| + | smtpd_tls_mandatory_protocols = TLSv1.2, TLSv1.1, !TLSv1 | ||
| + | </code> | ||
| + | |||
| + | Specific ciphers can be disabled as well. For a list of all ciphers that are available, use ''openssl'': | ||
| + | |||
| + | <code> | ||
| + | openssl ciphers | ||
| + | </code> | ||
| + | |||
| + | To make it easier to read, one per line: | ||
| + | |||
| + | <code> | ||
| + | openssl ciphers | tr ':' '\n' | ||
| + | </code> | ||
| + | |||
| + | You can find the ciphers or cipher family you'd like to drop by specifying the cipher list. For example:: | ||
| + | |||
| + | <code> | ||
| + | openssl ciphers MD5:aNULL | ||
| + | </code> | ||
| + | |||
| + | And then disable those in ''main.cf'': | ||
| + | |||
| + | <code> | ||
| + | smtp_tls_exclude_ciphers = MD5, aNULL | ||
| + | smtp_tls_mandatory_exclude_ciphers = MD5, aNULL | ||
| + | |||
| + | smtpd_tls_exclude_ciphers = MD5, aNULL | ||
| + | smtpd_tls_mandatory_exclude_ciphers = MD5, aNULL | ||
| + | </code> | ||
| ==== Virtual Domains and Aliases ==== | ==== Virtual Domains and Aliases ==== | ||
