Would someone please describe the configuration settings needed to support
TLS 1.2 and 1.3 with no weak ciphers? Here's what I currently have in my
configuration files:
main.cf:
smtpd_tls_cert_file=/etc/letsencrypt/live/mysite.net/fullchain.pem
smtpd_tls_key_file=/etc/letsencrypt/live/mysite.net/privkey.pem
smtpd_tls_security_level = may
smtpd_tls_mandatory_ciphers = high
smtpd_tls_protocols = >=TLSv1.2
smtpd_tls_mandatory_protocols = >=TLSv1.2
smtpd_tls_session_cache_database = btree:${data_directory}/smtpd_scache
smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache
smtpd_tls_dh1024_param_file = /etc/ssl/private/dh2048.pem
smtpd_tls_dh512_param_file = /etc/ssl/private/dh512.pem
master.cf:
submission inet n - n - - smtpd
-o syslog_name=postfix/submission
-o smtpd_tls_security_level=encrypt
-o smtpd_sasl_auth_enable=yes
-o smtpd_client_restrictions=permit_sasl_authenticated,reject
Here's what I see when I use nmap to retrieve the supported ciphers (note
that there are only TLS 1.2 ciphers listed, and some are weak):
$ nmap-ciphers 587 mysite.com
Starting Nmap 7.80 ( https://nmap.org ) at 2024-02-28 08:13 EST
Nmap scan report for mysite.com (173.255.237.114)
Host is up (0.00017s latency).
Other addresses for mysite.com (not scanned): 2600:3c03::f03c:91ff:fe70:dbb
rDNS record for 173.255.237.114: mysite.net
PORT STATE SERVICE
587/tcp open submission
| ssl-enum-ciphers:
| TLSv1.2:
| ciphers:
| TLS_DHE_RSA_WITH_AES_128_CBC_SHA (dh 2048) - A
| TLS_DHE_RSA_WITH_AES_128_CBC_SHA256 (dh 2048) - A
| TLS_DHE_RSA_WITH_AES_128_CCM (dh 2048) - A
| TLS_DHE_RSA_WITH_AES_128_CCM_8 (dh 2048) - A
| TLS_DHE_RSA_WITH_AES_128_GCM_SHA256 (dh 2048) - A
| TLS_DHE_RSA_WITH_AES_256_CBC_SHA (dh 2048) - A
| TLS_DHE_RSA_WITH_AES_256_CBC_SHA256 (dh 2048) - A
| TLS_DHE_RSA_WITH_AES_256_CCM (dh 2048) - A
| TLS_DHE_RSA_WITH_AES_256_CCM_8 (dh 2048) - A
| TLS_DHE_RSA_WITH_AES_256_GCM_SHA384 (dh 2048) - A
| TLS_DHE_RSA_WITH_ARIA_128_GCM_SHA256 (dh 2048) - A
| TLS_DHE_RSA_WITH_ARIA_256_GCM_SHA384 (dh 2048) - A
| TLS_DHE_RSA_WITH_CAMELLIA_128_CBC_SHA (dh 2048) - A
| TLS_DHE_RSA_WITH_CAMELLIA_128_CBC_SHA256 (dh 2048) - A
| TLS_DHE_RSA_WITH_CAMELLIA_256_CBC_SHA (dh 2048) - A
| TLS_DHE_RSA_WITH_CAMELLIA_256_CBC_SHA256 (dh 2048) - A
| TLS_DHE_RSA_WITH_CHACHA20_POLY1305_SHA256 (dh 2048) - A
| TLS_DH_anon_WITH_AES_128_CBC_SHA - F
| TLS_DH_anon_WITH_AES_128_CBC_SHA256 - F
| TLS_DH_anon_WITH_AES_128_GCM_SHA256 - F
| TLS_DH_anon_WITH_AES_256_CBC_SHA - F
| TLS_DH_anon_WITH_AES_256_CBC_SHA256 - F
| TLS_DH_anon_WITH_AES_256_GCM_SHA384 - F
| TLS_DH_anon_WITH_CAMELLIA_128_CBC_SHA - F
| TLS_DH_anon_WITH_CAMELLIA_128_CBC_SHA256 - F
| TLS_DH_anon_WITH_CAMELLIA_256_CBC_SHA - F
| TLS_DH_anon_WITH_CAMELLIA_256_CBC_SHA256 - F
| TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA (secp256r1) - A
| TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256 (secp256r1) - A
| TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 (secp256r1) - A
| TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA (secp256r1) - A
| TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384 (secp256r1) - A
| TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (secp256r1) - A
| TLS_ECDHE_RSA_WITH_ARIA_128_GCM_SHA256 (secp256r1) - A
| TLS_ECDHE_RSA_WITH_ARIA_256_GCM_SHA384 (secp256r1) - A
| TLS_ECDHE_RSA_WITH_CAMELLIA_128_CBC_SHA256 (secp256r1) - A
| TLS_ECDHE_RSA_WITH_CAMELLIA_256_CBC_SHA384 (secp256r1) - A
| TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256 (secp256r1) - A
| TLS_ECDH_anon_WITH_AES_128_CBC_SHA - F
| TLS_ECDH_anon_WITH_AES_256_CBC_SHA - F
| TLS_RSA_WITH_AES_128_CBC_SHA (rsa 2048) - A
| TLS_RSA_WITH_AES_128_CBC_SHA256 (rsa 2048) - A
| TLS_RSA_WITH_AES_128_CCM (rsa 2048) - A
| TLS_RSA_WITH_AES_128_CCM_8 (rsa 2048) - A
| TLS_RSA_WITH_AES_128_GCM_SHA256 (rsa 2048) - A
| TLS_RSA_WITH_AES_256_CBC_SHA (rsa 2048) - A
| TLS_RSA_WITH_AES_256_CBC_SHA256 (rsa 2048) - A
| TLS_RSA_WITH_AES_256_CCM (rsa 2048) - A
| TLS_RSA_WITH_AES_256_CCM_8 (rsa 2048) - A
| TLS_RSA_WITH_AES_256_GCM_SHA384 (rsa 2048) - A
| TLS_RSA_WITH_ARIA_128_GCM_SHA256 (rsa 2048) - A
| TLS_RSA_WITH_ARIA_256_GCM_SHA384 (rsa 2048) - A
| TLS_RSA_WITH_CAMELLIA_128_CBC_SHA (rsa 2048) - A
| TLS_RSA_WITH_CAMELLIA_128_CBC_SHA256 (rsa 2048) - A
| TLS_RSA_WITH_CAMELLIA_256_CBC_SHA (rsa 2048) - A
| TLS_RSA_WITH_CAMELLIA_256_CBC_SHA256 (rsa 2048) - A
| compressors:
| NULL
| cipher preference: client
|_ least strength: F
Nmap done: 1 IP address (1 host up) scanned in 2.17 seconds
$
Thanks for your guidance,
Scott
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