Red Hat Bugzilla – Bug 1282350
Support opportunistic STARTTLS for the incoming connections by default
Last modified: 2017-11-01 19:59:01 EDT
Currently the postfix server if installed by default does not support opportunistic STARTTLS for the incoming connections. It would be nice if a selfsigned certificate was generated as part of the installation or during the first startup of postfix similarly to what is done when mod_ssl is installed and the default configuration of postfix included 'smtpd_tls_security_level = may' setting so that opportunistic encryption of all mail transfer is enabled.
Although the self-signed certificate is not too useful for serving https web pages, it actually is much more useful in case of opportunistic encryption for SMTP. It does not prevent MITM attacks but in case of SMTP the attacker capable of doing MITM on the client side could probably also spoof DNS MX records and do MITM in much simpler way than to attack the actual connection. On the other hand the opportunistic encryption prevents mass-scale passive eavesdropping of the transferred e-mails and that is an useful goal to achieve by itself.
And actually the opportunistic encryption of outgoing connections should be enabled by default too by setting 'smtp_tls_security_level = may'.
Development Management has reviewed and declined this request. You may appeal this decision by reopening this request.
The need is supported by a recommendation by the Internet Architecture Board:
"The IAB now believes it is important for protocol designers, developers, and
operators to make encryption the norm for Internet traffic."
This is a simple change; a one-line configuration. It should be backported
wherever possible, not merely applied to future RHEL major versions.