diff --git a/mail-server/postfix.nix b/mail-server/postfix.nix index 5ef634f..39ad90a 100644 --- a/mail-server/postfix.nix +++ b/mail-server/postfix.nix @@ -66,7 +66,6 @@ in # Extra Config smtpd_banner = $myhostname ESMTP NO UCE - smtpd_tls_auth_only = yes disable_vrfy_command = yes message_size_limit = 20971520 @@ -83,6 +82,21 @@ in smtpd_sasl_path = private/auth smtpd_sasl_auth_enable = yes smtpd_relay_restrictions = permit_mynetworks, permit_sasl_authenticated, reject_unauth_destination + + # TLS settings, inspired by https://github.com/jeaye/nix-files + smtpd_tls_security_level = may # Submission by mail clients is handled in submissionOptions + smtpd_tls_eecdh_grade = ultra # strong might suffice and is computationally less expensive + smtpd_tls_protocols = !SSLv2, !SSLv3 # Disable predecessors to TLS + smtpd_tls_auth_only = yes # Allowing AUTH on a non encrypted connection poses a security risk + smtpd_tls_loglevel = 1 # Log only a summary message on TLS handshake completion + + # Disable weak ciphers as reported by https://ssl-tools.net + # https://serverfault.com/questions/744168/how-to-disable-rc4-on-postfix + smtpd_tls_exclude_ciphers = RC4, aNULL + smtp_tls_exclude_ciphers = RC4, aNULL + + # Configure a non blocking source of randomness + tls_random_source = dev:/dev/urandom ''; submissionOptions =